Talk:Scientific consensus on climate change/Archive 18

DNFTT
That is all William M. Connolley (talk) 23:00, 12 February 2013 (UTC)
 * Agree. --Nigelj (talk) 23:29, 12 February 2013 (UTC)
 * edit conflict, but I'll go with it anyway. See below. NewsAndEventsGuy (talk) 23:43, 12 February 2013 (UTC)

POLL  Are either of Cybersaur's proposed sources what wikipedia considers to be a reliable source?
Poll Background

Starting in December, user (under that name or any of a number of IP accounts) has started or perpetuated a lot of talk page threads here and also at Global warming controversy which, in my retroactive opinion at least, are WP:SOAP. There have been a lot of requests that he name his proposed sources. The typical response has been a vague reference to alleged groups with almost no links, no bibliography, and nothing tangible we can actually look up, read, and discuss. This is getting close to blockable [[WP:DISRUPT|disruptive However, he has finally produced two salient proposals that we need to process. If cybersaur can not persuade us to use either of these sources, then he will have the choice to either (A) cross the disruption line by further opinion-based argument despite the clear consensus, or (B) take the appropriate next step according to the DR process, perhaps by moving on to the reliable sources noticeboard.

To my knowledge, the pending proposed sources are
 * (A) What a Cybersaur IP quotes from the ICSC mission statement
 * "Climate change takes place over geological time scales of thousands through millions of years, yet unfortunately geological datasets do not provide direct measurements, least of all of global temperature. Instead, they comprise local or regional proxy records of climate change of varying quality. Nonetheless, numerous high quality palaeo-climate records, and especially those from ice cores and deep-sea mud cores, demonstrate that no unusual or untoward changes in temperature occurred in the 20th and early 21st century. Nor are carbon dioxide levels high compared with the geological past. Despite an estimated spend of more than $100 billion since 1990 looking for a human global temperature signal, assessed against geological reality no compelling empirical evidence yet exists for a measurable, let alone worrisome, human impact on global temperature."
 * - For this Cybersaur cited the ICSC Mission Statement p.4, which I have not confirmed as ICSC registration is apparently required
 * (B)What a Cybersaur IP quotes from Heartland Institute
 * "The International Climate Science Coalition (ICSC) today called on world leaders to announce a common sense approach to climate change instead of yielding to popular, but misguided demands to restrict greenhouse gas (GHG) emissions to 'stop climate change'."(emphasis in original)
 * - For this, instead of repeating cybersaur's low value cite I am providing a link to this Heartland document

POLL QUESTION What say ye? Do we view the ICSC mission statement as an WP:RS? How about the Heartland quote? NewsAndEventsGuy (talk) 23:42, 12 February 2013 (UTC)

!Votes and comments
 * NO (I will add/repeate my reasons later) NewsAndEventsGuy (talk) 23:42, 12 February 2013 (UTC)
 * No For the purposes of this article, as defined in the lede section, it doesn't matter what an organisation has said unless they are a "scientific bod[y] of national or international standing". I would say that the definition of that would hinge on whether most of the other such bodies recognise them as one of their kind and treat them as such. I'm certain that no evidence showing that the ICSC or Heartland Institute is widely regarded as such a scientific body will ever be forthcoming. Until someone comes up with convincing evidence that they are, we have to go with what we all know anyway - that they are not. --Nigelj (talk) 00:09, 13 February 2013 (UTC)
 * I agree of course, but IMO this reason for not using them falls in the "off point" camp, and does not address the question whether they are RSs. NewsAndEventsGuy (talk) 00:14, 13 February 2013 (UTC)
 * OK. To the specific question, the ICSC mission statement is a reliable source only for it's own position. In other words, we can confidently state that what that webpage says is almost certainly the actual position of the ICSC. But where does that get us? Nowhere with regard to this article, in which the opinion of the ICSC is utterly irrelevant per what I said in my !vote above. --Nigelj (talk) 19:43, 13 February 2013 (UTC)
 * (Blush) Indeed, the poll, with its emphasis on RELIABLE SOURCE qualification, would have been better located at Global warming controversy. Here there is little dispute that the mission statement is a statement disputing the three numbered points in the lead, so your initial answer is really the meat of the matter for this article's purpose.NewsAndEventsGuy (talk) 21:27, 13 February 2013 (UTC)


 * No There is no evidence that these lobby groups do any science. TippyGoomba (talk) 06:55, 13 February 2013 (UTC)
 * No as these are fringe self-published sources which clearly fail to meet the requirement of WP:SOURCES policy for reliable, third-party, published sources with a reputation for fact-checking and accuracy. At best they're WP:NOTRELIABLE, and in relation to WP:SPS this article is clearly offtopic: it's not an article about them. . . dave souza, talk 09:23, 13 February 2013 (UTC)
 * No - no independent evidence of notability. The starting point for the conversation would be to establish (via reliable secondary sources which are independent of the group) that they are a notable scientific society. Guettarda (talk) 14:04, 13 February 2013 (UTC)
 * YES - Here's why: (a) We don't have to have organizations "international standing," but even if we did, the ICSC IS. Obviously, if you define "international standing" as government controlled, it isn't, but we don't have to. (b) The ICSC is well-known. It was invited to the UN's climate change conference. (c) The ICSC is SCIENTIFIC. It is run by scientists, and it is obvious that they do scientific research. You guys seem to have a very narrow and warped definition of "scientific". (d) This page needs to be less biased towards one side of the argument. We need SOMETHING in this section. (e) In the "consensus" section, there are LOADS of organizations that are on there and are self published, and there's no evidence that they are any more credible than the ICSC. (f) You can find crazy stuff about any organization, with people saying they're "corrupt". Even the IPCC.(g)It isn't self-published anyway. it's from heartland.72.80.200.132 (talk) 16:35, 13 February 2013 (UTC)
 * Do you have supporting citations for your claims? ("Published by Heartland" is self-published, but the look of it. And "published by Heartland" is worse than run-of-the-mill self-published sites, given Heartland's dubious record on climate change.) Guettarda (talk) 17:09, 13 February 2013 (UTC)
 * You may call it "dubious", but, like I said, you can find evidence saying even the IPCC is corrupt, and that its "peer-review" is a sham.72.80.189.192 (talk) 22:48, 13 February 2013 (UTC)
 * I'll take "sham" peer review over no peer review. Also, do you have the peer review to back up your claim of sham peer review? or is this more self-published nonsense? Check out time cube, it's all true, the website says so. TippyGoomba (talk) 04:02, 14 February 2013 (UTC)


 * No - Heartland is not a reliable source on science, period. The ICSC quote is a WP:RS on what the ICSC thinks, but does not establish their notability, nor whether they are a WP:RS on scientific issues. Cybersaur has provided no second- or third-party evidence that ICSC is a scientific organization (I think the only third party cite was to sourcewatch or exxonsecrets!), nor any references to any of their peer-reviewed climate science publications, nor even any references to suggest that they are particularly notable (a quick Google search did not turn up any obvious newspaper references to them). If such are provided, I could be convinced to change my vote. - Parejkoj (talk) —Preceding undated comment added 03:53, 14 February 2013 (UTC)
 * No, for the reasons given by Parejko. Furthermore, Cybersaur's (72.80*) arguments are entirely uncredible, on par with Time cube. ~ J. Johnson (JJ) (talk) 20:40, 23 February 2013 (UTC)


 * Comment. This poll seems to be complete, with the result that neither the ICSC nor Heartland are considered reliable sources regarding either the science of global warming, or scientific opinion regarding the science. I am sure that 1) Cybersaur is not convinced, and 2) none of the rest of us doubted that. Possibly Cybersaur might be convinced that "all editors" (at least those who expressed an opinion, and the rest really don't count) disagree with him in this matter. In the likely event he is not: can we consider this point settled, and further discussion unnecessary? ~ J. Johnson (JJ) (talk) 21:08, 23 February 2013 (UTC)

American Association for the Advancement of Sciences conference update, include here?
99.112.212.232 (talk) 02:43, 27 March 2013 (UTC)
 * Nations Change Too Slowly to Combat Climate Change; A conference at the American Association for the Advancement of Sciences notes that the incremental steps taken to address global warming are not enough March 21, 2013 ClimateWire via Scientific American, per Global Environment Facility

Lede
From the sources in the lede

Source #1 - Climate change in IPCC usage refers to a change in the state of the climate that can be identified (e.g. using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer. It refers to any change in climate over time, whether due to natural variability or as a result of human activity. This usage differs from that in the United Nations Framework Convention on Climate Change (UNFCCC), where climate change refers to a change of climate that is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and that is in addition to natural climate variability observed over comparable time periods.

Source #2 - Where uncertainty in specific outcomes is assessed using expert judgment and statistical analysis of a body of evidence (e.g. observations or model results), then the following likelihood ranges are used to express the assessed probability of occurrence: virtually certain >99%; extremely likely >95%; very likely >90%; likely >66%; more likely than not > 50%; about as likely as not 33% to 66%; unlikely <33%; very unlikely <10%; extremely unlikely <5%; exceptionally unlikely <1%.

Source #3 - Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG concentrations. This is an advance since the TAR’s conclusion that “most of the observed warming over the last 50 years is likely to have been due to the increase in GHG concentrations”.

Source #4 - there is a strong, credible body of evidence, based on multiple lines of research, documenting that climate is changing and that these changes are in large part caused by human activities.

Using these four sources it is correct to state from the sources that the IPCC says that they are 90% certain that humans are causing a large part of the change in climate. Source 1 clearly states that there may be natural variability. Source 2 is there simply to express the relationship between the 90% and the wording being used by the IPCC. Source 3 expresses that most of these increases are due to anthropogenic greenhouse gases. Now what is the problem with stating it in the lede in this manner? Arzel (talk) 20:56, 7 April 2013 (UTC)


 * Source 1 does indeed state that there may be natural var. But that doesn't help, since that can be up or down. Sources 3 and 4 are better, but they are only summaries. Reading IPCC WG1 directly is more useful William M. Connolley (talk) 22:06, 7 April 2013 (UTC)
 * William, I notice you think source 3 is better than either 1 or 2. In fact, source 3 is where the phrase "most of" appears in the same sentence that links to the "very likely" language that is defined as >90% certain.  As this is straight-out-of-the-RS-letter-for-letter, I've already edited the article to this effect.  If you can persuade me that WG1 said "all", I'd be happy to do the grunt work to swap out RS3 for the whatever WG1 cite you use to persuades me. NewsAndEventsGuy (talk) 23:14, 7 April 2013 (UTC)


 * (ec)That source only confirms the point. "It is extremely unlikely (<5%) that recent global warming is due to internal variability alone such as might arise from El Niño (Section 9.4.1)"  i.e., it is extremely likely that something else is causing the change, but in statistical verbiage it is not an absolute statement.  Then with this statement, "The consistency across different lines of evidence makes a strong case for a significant human influence on observed warming at the surface." where the word significant means >90% (maybe 95%, but they don't put their wording classification on that statement, I suppose it could be >66%, but I have never seen that cutoff used for a statistical significance statement) but < 100%.  Add in "It is theoretically feasible that the warming of the near surface could have occurred due to a reduction in the heat content of another component of the system." and you can in no way say that they are 90% certain that humans are entirely responsible, they don't even say that.  They say they are 90% certain that human influence is driving the observed warming at the surface.  They certainly don't say that natural variation stopped within the past couple hundred years (which is what the original statement would have to mean.  On top of this, you know that this is the way statistical hypothesis testing works.  Arzel (talk) 23:22, 7 April 2013 (UTC)
 * Going back a bit, the edit summary that "No respectable scientist would ever make an absolute statement" is false as well as being a smear: a range of certainty isn't absolute, and SkepSci cites a series of sources with the summary that "Over the most recent 25-65 years, every study put the human contribution at a minimum of 98%, and most put it at well above 100%, because natural factors have probably had a small net cooling effect over recent decades." Not in itself a RS, but links to published papers. Note that the human contribution isn't just greenhouse gases, and AR4 linked by WMC also says that it is likely that "Increases in greenhouse gas concentrations alone would have caused more warming than observed over the last 50 years because volcanic and anthropogenic aerosols have offset some warming that would otherwise have taken place." More warming has since been observed, and the effect of aerosols is under question so we should take care not to imply that human causes are only part of the cause of global warming. . . dave souza, talk 23:37, 7 April 2013 (UTC)
 * That was not a smear, and I would repeat it in a second. Furthermore, Jones, et al, doesn't appear to make an absolute statement either.  Even the summary of the paper does not make that statement, plus 2 or 3 of the models used show < 100% attributed to man.  Regardless you do realize you cannot use it to support that statement, unless that statement is adopted as scientific consensus.  Given that the study came out in March of this year, I don't see that happening for at least some time.  Arzel (talk) 23:59, 7 April 2013 (UTC)
 * It was a smear because you were (wrongly) implying that no scientist would put the human contribution at more that 100%. Even AR4 puts it as likely that GHGs alone would cause more warming than observed, a lot depends on the side-products of activities that increase concentrations of greenhouse gases in the atmosphere, such as particulates. So, our wording needs to be tightened and should not underweight the human contribution. . dave souza, talk 00:11, 8 April 2013 (UTC)
 * No I said that no scientist would make an absolute statement. Now perhaps I should have prefaced it that no scientist would make an absolute statement regarding a system with unknown error, but I assume that those here are knowledgeable enough about scientific theory.  Arzel (talk) 02:52, 10 April 2013 (UTC)

smear, schmeer, sgahlahhmeeere.......  Are we still discussing proposed article edits based on RSs, because all I hear at the moment is soap and forum. And I'd be happy to up the 90% or remove the "most of" if we have the RSs to support that. NewsAndEventsGuy (talk) 00:19, 8 April 2013 (UTC)
 * As it says in the opening para of AR4 SYR 2.4, "It is likely that increases in GHG concentrations alone would have caused more warming than observed because volcanic and anthropogenic aerosols have offset some warming that would otherwise have taken place." I've added that quote and tried to reflect it in the lead. There's also the emerging issue of more warming going into deep water than previously thought, but maybe still early for full consensus on that. . dave souza, talk 00:42, 8 April 2013 (UTC)
 * Additional sentence about aerosols suppressing effect of atmospheric greenhouse gases looks good to me. NewsAndEventsGuy (talk) 01:29, 8 April 2013 (UTC)

A said: ''They say they are 90% certain that human influence is driving the observed warming at the surface. They certainly don't say that natural variation stopped...'' This has some confusions in it. The 90% is a confidence estimate, but it doesn't refer to fraction of observed warming being attributed to different sources. That latter is what we're talking about, so the 90% is irrelevant in this context. As for nat var stopping: no indeed, no-one is suggesting that it has (though its become less important as a fraction of total change). But neither is anyone suggesting that nat var must necessarily be positive. However the average assumption for nat var is that overall/over-long-time its effects are about zero. Without evidence to the contrary, its as likely that humans have caused more than 100% of the observed change as they've caused less William M. Connolley (talk) 09:41, 9 April 2013 (UTC)
 * I realize that the 90% is a level of confidence, but even the new paper does not say equivocally that humans are 100% responsible for the observed warming. Some of the models attribute the change to natural variation and it would appear that a couple more would have confidence levels themselves which cross the threshold.  There are no odds ratios included in the abstract and I don't have access to the whole paper to see the actual statistical values so those levels are not completely known other than what is observable from the graph.  The statement that humans have caused 100% (or more) of the increase in temperatures is problematic for several reasons.  The assumption that some are making is that human release of GHG have caused a (simulated) certain increase in temps in excess of the observed increase in temps, while natural factors have contributed a smaller about (possibly cooling), but if it is positive you can't say that humans are 100% responsible for the observed warming.  As for your final statement, the corollary is just as true.  Its as likely that humans have caused less than 100% of the of the observed change.  Of course in a few years if the increase in temps falls outside of the statistical range of the predictions for all models; this whole argument will be naught as we will have sufficient evidence that the models have been poor from the beginning.  Arzel (talk) 02:52, 10 April 2013 (UTC)
 * Your opening post appaers to be resolved, which suggests that this thread should die. The text now says what the cited RSs say:  they are >90% certain we are doing most of it.   Without a specific proposal for improving the article still pending, further debate is WP:SOAP and WP:FORUM NewsAndEventsGuy (talk) 04:16, 10 April 2013 (UTC)
 * I'm still not happy with that, but will need to dig up the refs to fix it. A is still missing the point William M. Connolley (talk) 09:35, 10 April 2013 (UTC)
 * Same here, William. NewsAndEventsGuy (talk) 11:49, 10 April 2013 (UTC)

Other notable sources, e.g., the Stockholm Memorandum
I think this is generally a good article, but in my opinion, there are some notable omissions: Enescot (talk) 06:17, 14 February 2013 (UTC)
 * I think that the US National Research Council's reports on "America's Climate Choices" should be listed in the section on "synthesis reports".
 * There is a petition of 2,000 US scientists and economists who support deep reductions in US greenhouse gas emissions - "signatories [include] eight Nobel Prize winners in science or economics, 32 members of the National Academy of Sciences, 10 members of the National Academy of Engineering, 11 recipients of the MacArthur Fellowship, three National Medal of Science recipients, and more than 100 members of the Intergovernmental Panel on Climate Change"
 * The 2007 Bali Declaration by Scientists was signed by many distinguished climate change researchers, such as Steve Schneider.
 * The Stockholm Memorandum, which supports the UNFCCC's 2 degrees Celsius global warming target: "The Symposium took place at the Royal Swedish Academy of Sciences in Stockholm between 16-19 May [2011] and gathered some 50 of the world’s most renowned thinkers and experts on global sustainability – half of them Nobel Laureates."
 * Petitions are really bad sources for views, and rather unusable for determining general views within a field (which is what we need here), for several reasons: selection bias (people are self-selected); people sign petitions because they like some parts of them but do not necessarily agree with everything in them. --Kim D. Petersen (talk) 08:36, 16 February 2013 (UTC)
 * I think that experts who agree with the scientific consensus on climate change, or who support various climate change policies, should be mentioned somewhere on Wikipedia. There already is a list of scientists opposing the mainstream scientific assessment of global warming, and in my opinion, people and organizations who support the scientific consensus on global warming would be a reasonable addition.


 * In my opinion, lists and petitions are both relevant to this article, since they both contain information about scientific opinion on climate change. To be relevant, I do not think that scientific opinion on climate change has to reflect a consensus view.


 * It's difficult for me to see how petitions with highly distinguished signatories can be viewed as bad sources. For example, the Bali Declaration was signed by James J. McCarthy (who previously served as a co-chair of the IPCC TAR Working Group II report) and Thomas Stocker (currently a co-chair of IPCC Working Group I).


 * I agree that petitions will not necessarily reflect a general view within a field. However, this isn't a problem in this article. Other sources such as the IPCC report are cited, as well as statements made by various science academies. If a petition has been criticized, e.g., the Oregon Petition, then that information can be included as well.


 * The issue of selection bias also applies to science academies, as well as assessment reports like the IPCC. Statements by scientific academies will not necessarily reflect the views of all of their members. For example, Richard Lindzen, who is a member of the US National Academy of Sciences, has criticized the US National Academies statement on climate change. Many members of an organization like the AAAS will probably not be experts on climate change. The IPCC has been criticized for its authors section process. Enescot (talk) 06:19, 18 February 2013 (UTC)
 * No petitions. Petitions are inherently political; Scientific consensus arises from the a -political assessment of evidence.  The exclusion of petitions helps filter out political noise from the scientists' evidence-assessment signal. NewsAndEventsGuy (talk) 07:55, 18 February 2013 (UTC)
 * Funny that you think petitions are "politicized" but you think politically controlled organizations like the IPCC, who only look at evidence that agrees with them, arn't. Petitions are not political, that is absurd.72.80.203.156 (talk) 16:25, 19 February 2013 (UTC)
 * Actually, the claim about the IPCC is vacuous - the IPCC summarizes all relevant peer-reviewed paper, so of course they all "agree" with the published reports. In particular, they take into account papers that disagree with the resulting consensus, and mention them in the reports. And, of course, the IPCC is not alone - all the National Academies of Science agree, as do literature overviews by individual scientists, as do nearly all scientists who are active in the field. --Stephan Schulz (talk) 17:17, 19 February 2013 (UTC)
 * I'm really surprised at the response to Enescot's suggestion. Maybe instead of focusing on any petition written by those bodies, the bodies themselves and perhaps their statements should be listed. They are the following: Concerned Union of Scientists, a "consensus document was prepared under the auspices of the Climate Change Research Centre at the University of New South Wales in Sydney, Australia," a memorandum from the Royal Swedish Academy of Sciences in Stockholm. Yopienso (talk) 17:47, 19 February 2013 (UTC)
 * Peer review, peer review, peer review! I'm tired of people going on and on about peer review. Peer review, believe it or not, does not make an organization perfect. All "peer review" even means is that a few random people went over it who probably already agreed with the content. If you think anything that uses peer review is inherently right, just look at this recent evidence I found:


 * Forbes, February 13, 2013. "Peer-Reviewed Survey Finds Majority Of Scientists Skeptical Of Global Warming Crisis" http://www.forbes.com/sites/jamestaylor/2013/02/13/peer-reviewed-survey-finds-majority-of-scientists-skeptical-of-global-warming-crisis/


 * Don’t look now, but maybe a scientific consensus exists concerning global warming after all. Only 36 percent of geoscientists and engineers believe that humans are creating a global warming crisis, according to a survey reported in the peer-reviewed Organization Studies. By contrast, a strong majority of the 1,077 respondents believe that nature is the primary cause of recent global warming and/or that future global warming will not be a very serious problem.
 * 72.80.203.156 (talk) 17:35, 20 February 2013 (UTC)


 * Peer review, peer review, peer review! I'm tired of people going on and on about peer review... Peer-Reviewed Survey Finds.... Make up your mind. Either you're contemptuous of peer-review (in which case you shouldn't be pushing stuff that you only think valid because its been PR) or you think PR is valid (in which case you have to deal with the problem that the PR literature says stuff you don't like). In this particular case the lie-by-omission you're committing is failing to mention that these are all petroscientists in Alberta William M. Connolley (talk) 18:01, 20 February 2013 (UTC)
 * You don't seem to understand my point. All I was saying is that just because something is peer-reviewed, that doesn't make it perfect. My example was merely given to illustrate that you can find "peer reviewed" articles saying just about anything.PS: what do you mean exactly by "petro-scientists"?72.80.203.156 (talk) 18:32, 20 February 2013 (UTC)
 * Oh, so you do think the study you've ref'd is junk. Good. Petro as in petroleum. They're all oil geologists. Funny how you didn't bother mention that William M. Connolley (talk) 18:45, 20 February 2013 (UTC)
 * Actually, the Forbes interpretation is junk and a bad example of extremely selective reading. The original study seems reasonable (and acknowledges the consensus view: "...there is a broad consensus among climate scientist..."). The authors looked hard to find a group that disagrees to analyze their behavior and "demonstrate that the majority of ‘command posts’ within organizations, especially in the petroleum industry, seem to be manned with opponents to the IPCC and anthropogenic climate science who are actively engaged in defensive institutional work." --Stephan Schulz (talk) 19:02, 20 February 2013 (UTC)
 * Let's not forget the petroleum guys' Alberta-based industry (home of the tar sands now in the news) will profit huge if DC approves the Keystone pipeline. NewsAndEventsGuy (talk) 19:48, 20 February 2013 (UTC)
 * (reply to NewsAndEventsGuy's initial reply): I disagree. Given the title of the article, petitions signed by experts qualify as scientific opinion. In my opinion, the distinction you make between "political" and "apolitical" assessments is flawed.


 * The idea that assessments be should be apolitical is inconsistent with some, most, or all of the science academy statements. For example:


 * (from the article)"In December 2009, the national science academies of the G8+5 nations issued a joint statement declaring, "Climate change and sustainable energy supply are crucial challenges for the future of humanity. It is essential that world leaders agree on the emission reductions needed to combat negative consequences of anthropogenic climate change"


 * The statement goes on to recommend an emissions target.


 * (from the article)''"[In 2001, following] the publication of the IPCC Third Assessment Report, seventeen national science academies issued a joint statement, entitled "The Science of Climate Change":"


 * (from the statement) "The ratification of [the Kyoto] Protocol represents a small but essential first step towards stabilising atmospheric concentrations of greenhouse gases. It will help create a base on which to build an equitable agreement between all countries in the developed and developing worlds for the more substantial reductions that will be necessary by the middle of the century.


 * The balance of the scientific evidence demands effective steps now to avert damaging changes to the earth’s climate.


 * These are political statements made by science academies. By your logic, these statements, and others like them, should be excluded from this article.


 * I'm also confused as to how the IPCC is, for some reason, deemed to above this as an issue. Experts such as Richard Tol and Hans von Storch  have commented on the political aspects of climate change science. A 2010 assessment by the Netherlands Environment Agency evaluated the IPCC Fourth Assessment Working Group II Report (p.38):


 * "As a result of the approach that was followed, mostly negative impacts were singled out (in the summaries). In fact, the reason why hardly any example of a positive impact of climate change can be found in Table SPM.2 of the Synthesis Report is that, according to the IPCC authors, most of the positive impacts were not of sufficient policy relevance"


 * In any case, I don't see why this article should exclude scientists and other experts who have expressed a political view. Their political views are based on an informed assessment of the scientific evidence. Since these political views are those of experts (natural and social scientists), they qualify as being "scientific opinion." Enescot (talk) 10:02, 21 February 2013 (UTC)
 * The trouble here is that you are confusing the "collective opinion within a particular field of science" with the "opinion of a select group of scientists with in a field". The latter is a very small subset of the former, which may or may not be representative of the collective opinion. --Kim D. Petersen (talk) 11:44, 21 February 2013 (UTC)
 * When the academies say the politicians have got to get serious about emissions reductions they are making their recommendations. At that point in their statement their apolitical "assessment" of the peer-reviewed scientific literature has already been completed, and there's at least some degree of checks and balance to keep it honest via the groups internal procedures.  Although some exceptions might exist, by and larger there are no such checks or balances involved for most opt in petitions.  People can sign those for all sorts of reasons, whether they have "assessed" the peer-reviewed scientific literature or not.  NewsAndEventsGuy (talk) 12:20, 21 February 2013 (UTC)
 * When the academies make recommendations to politicians, it's extremely hard to see those recommendations as "apolitical". I'd like to see some evidence from reliable sources of the assertions made by editors above on how scientific consensus is formed; and the gist of those references should be added to the article, to explain what kind of opinions have been included in it. A summary style section of the relevant parts of Scientific consensus, with a summary of its basic and more general references, should be enough for this purpose. It seems weird that Scientific consensus includes more information about the politicization of global warming science than the very article describing it. Diego (talk) 13:31, 21 February 2013 (UTC)
 * Taking Enescot's italicized example above, I don't see it as anything other than science. For example, suppose they said "Empirical observations indicate that you are swinging a 3 pound sledge at your head. The balance of the scientific evidence regarding the laws of motion as well as neurology demand effective steps now to avert damaging changes to your cerebral cortex."  This is an apolitical assessment of what one is doing, and the natural consequences inherent in one's available options.  The sciences involved are physics, neurology, and psychology.  No one has any genuine quibbles with characterizing the smashed skull as "damaging" to this fellow's cerebral cortex, do they?  If that was an apolitical statement about the sledge-swinger, then I think we're done here.   NewsAndEventsGuy (talk) 15:55, 21 February 2013 (UTC)
 * You guys are using circular reasoning: First, you say there is a scientific consensus. Then you say that your source saying there is a scientific consensus is better than our sources, which are "unscientific." Then, when we ask you WHY they're unscientific, you say that its because they don't support the "consensus". Then, we ask you to tell us why you think there IS such a consensus, and you bring up the old source again! Stop traveling in circles!
 * Our evidence is every bit as "scientific"as yours. you keep on bringing up all this stuff about “oil companies”. Well, guess what: not everyone who tries to improve peoples’ lives by mining for oil is evil! You say all the scientists in the petition were “petro-scientists”. Funny that you don’t have any evidence to prove it, but even if you did it wouldn't matter, because they're still climate scientists. It really doesn't matter where they get their funding, either. How is government funding any better than oil-company funding? In fact, one would think that government funding would be even worse, because nowadays every time the government gets their hands on something, especially science, it ends up as a disaster.72.80.203.156 (talk) 19:43, 22 February 2013 (UTC)
 * Climate scientists publish papers, which oil and coal industry funded hacks generally fail to do. The academies have a duty to represent science, unlike your friends whose product is doubt. . dave souza, talk 22:59, 22 February 2013 (UTC)
 * I don't know what you mean about "unlike your friends". However, I don't see how "publishing papers" makes you SOOO scientific. There are plenty of smart people out there that "publish papers", and plenty of idiots that do the same. The people in this survey, the people in the petition, and the people in the ICSC are all SCIENTISTS, with PhDs. They arn't "coal and oil industry" people. It makes absolutely no difference where their funding comes from. Every organization has got to get funding SOMEHOW. I no that if I were starting a scientific organization, and exxon mobil told me they wanted to fund me, I'd certainly accept, and I think you would too.


 * "duty to represent science"? These are government agencies we're talking about. They have no more motivation torepresent science than I do. The only motivation they have is to stay in office and do whatever the government tells them to do. The only motivation the ICSC has is to keep th oil companies happy. Therefore, the two are equally "unscientific".


 * Well, I guess I'll go and write a paper and get it "published" by getting my friends to put it on facebook, and then I'll go get it "peer-reviewed" by all my friends who already agree with it. That'l make it SCIENTIFIC, RIGHT??!!72.80.192.180 (talk) 00:09, 23 February 2013 (UTC)

Could you please give your suggested change along with the appropriate sources. Thanks. TippyGoomba (talk) 03:18, 23 February 2013 (UTC)
 * Since nobody said anything against my arguments, but only asked for a source, I take it you all agree with me that petitions are reliable. Well, for starters I think that the stuff at the top of this section is perfectly fine. I see nothing wrong with it. Naturally, it contradicts some of my personal opinions, but opinions count for nothing. They are obviously scientific petitions. However, if you want me to bring up some of my own sources, I'd be happy to. My original source, the ICSC, was voted down because of personal beliefs. My arguments were ignored, so I take it no one will accept that. I have my doubts as to whether anyone will accept ANYTHING that contradicts your precious global warming ideology, but I do know two notable things to mention: First, there's the Oregon petition, signed by 31,000 scientists, renouncing global warming. Then there's the above-mentioned survey, ehich says that only 36% of scientists believe global warming. There's no reason to bring up a SPECIFIC quotation yet, because I'm sure you guys will have bone to pick with the petitions themselves, in which case we should argue that out before we get to any specific sources.72.80.192.180 (talk) 06:30, 23 February 2013 (UTC)
 * I don't see a suggested change or a source. Perhaps you should read WP:FORUM. TippyGoomba (talk) 07:13, 23 February 2013 (UTC)
 * I just TOLD you, we need to decie whether these petitions/surveys are RELIABLE before we decide how to cite them.72.80.192.180 (talk) 17:28, 23 February 2013 (UTC)
 * Offsides, 20 yard penalty.  The first thing to decide is whether petitions are related to the subject of the article at all.  Several of us have already charted out the disagreement on that point earlier in this thread. NewsAndEventsGuy (talk) 18:16, 23 February 2013 (UTC)
 * NAEG, have to disagree. The first thing is for our petition loving friend to provide reliable third party sources showing some significance of these petitions to the topic, and to propose improvements to the wording based on such sources, giving due weight to mainstream views about these petitions. . . dave souza, talk 19:01, 23 February 2013 (UTC)
 * I disagree that you disagree (insert laughter). I think you agreed with different words, where you describe the first thing as finding "reliable third party sources showing some significance of these petitions to (the scientific consensus on climate change)".  That's pretty much what I said, or tried to. NewsAndEventsGuy (talk) 19:08, 23 February 2013 (UTC)
 * Yeah, sorta. The first thing is good quality secondary / third party sources, not the claims of the petition promoters themselves. . dave souza, talk 19:55, 23 February 2013 (UTC)
 * Nah, the first thing this denizen of an alternate reality needs to do is get on the same wave-length as the rest of us. And the first thing everyone else needs to recognize is that he is not on the same wave-length, that he doesn't even understand the concepts involved here. It is pointless (and a waste of time) to ask him to provide "reliable third party sources" when he does not understand what is meant by reliable. How can we even talk with someone who rejects everyone else's argument as "that's your opinion"? ~ J. Johnson (JJ) (talk) 21:57, 23 February 2013 (UTC)
 * Well, its quite true that none of you are providing any reliable sources affirming that my sources are unreliable...at least no more sources than I could provide saying any number of non-dissenting organizations aren't reliable. On this very page, in the "consensus" section, there are organizations mentioned that arn't even introduced to the reader as reliable, and the IPCC is SELF PUBLISHED in many places. Everyone has been ignoring this since day 1. However, I do not wish to be sanctioned, and people are threatening it...So I will find some more SOURCES.72.80.192.180 (talk) 04:44, 25 February 2013 (UTC)
 * Finding sources is simple - but now that you know about our criteria for reliable sources please try harder not to WP:DISRUPT things by bringing a deluge of unreliable ones. NewsAndEventsGuy (talk) 06:06, 25 February 2013 (UTC)

reply to Kim D. Petersen's response to my earlier comment: I don't see why this article should focus so heavily on the views of scientific academies. In my view, this article should provide a balanced summary of all scientific opinion on climate change. Obviously, the views of science academies are important, but I think that my sources are also worth mentioning. The sources I have cited are reliable, and reflect the views of some experts.

I also agree with some of criticisms of this article raised by other editors. In the current revision, I do not think that dissenting experts are given enough space. I recognize that "fringe" views should not be given undue weight, but they should be given some coverage. This also applies to experts who think that too little is being done to address climate change, such as James Hansen.

In my opinion, the article is structured to exclude the views of certain groups. For example, the political views of the science academies are implicitly favoured over those of other analysts and commentators. For example, many economists have criticized the Kyoto Protocol, but this is not mentioned. There is no explanation that the recommendations of science academies are inherently political (see below). In regards to climate policy, everyone is entitled to an opinion.

Another problem is the focus on attribution of climate change. There is no "scientific" reason why this should be emphasized over other issues, for example, the projected impacts of climate change. In my opinion, this unwarranted focus is probably due to the political attention that attribution has received in the United States and in other English-speaking countries. The UNFCCC was adopted before human attribution was established. Recommendations to cut emissions pre-date the UNFCCC (p.7). Enescot (talk) 06:25, 28 February 2013 (UTC)
 * reply to NewsAndEventsGuy's response to my earlier comment:: Here's a quote from the IPCC report: "Defining what is dangerous interference with the climate system is a complex task that can only be partially supported by science, as it inherently involves normative judgements. There are different approaches to defining danger, and an interpretation of Article 2 is likely to rely on scientific, ethical, cultural, political and/or legal judgements. As such, the agreement(s) reached among the Parties in terms of what may constitute unacceptable impacts on the climate system, food production, ecosystems or sustainable economic development will represent a synthesis of these different perspectives." Enescot (talk) 06:27, 28 February 2013 (UTC)
 * Enescot, you seem to be confusing economists with climate scientists, and proposing undue weight to a tiny minority who are more likely to get their opinions in the WSJ than publish a scientific paper. If we mention them at all, they have to be shown in the context of the industry led political disinformation machine. I notice that you're quoting WG3, which is about economic assessment rather than the hard science of WG1. . . dave souza, talk 09:53, 28 February 2013 (UTC)
 * It's also a red herring since the three numbered paragraphs in the lead assess the science but stop short of assertions as to how much warming is "dangerous interference". NewsAndEventsGuy (talk) 13:15, 28 February 2013 (UTC)


 * I find this rather confusing. The scientific academies make what are clearly political statements over what should be done about climate change - see my earlier posts for examples. To me, it is self-evident that readers of this article will want to know what should be done about climate change. This issue has been discussed in the scientific literature – e.g., see and my earlier posts.


 * In my opinion, the political recommendations of the science academies should be placed in the context of other views on climate change policy. There are a wide range of views on what should be done about climate change. This is why I want to add information on the statements which support the 2 degrees C target. Other opinions have been expressed by politicians, NGOs, and experts in the policy literature.


 * Economic analysis is referred to in the lede - "On balance the impacts of global warming will be significantly negative, especially for larger values of warming." One of the aggregate measures used by Smith et al is gross domestic product. As an aside, the above statement is a misreading of the cited source.


 * The IPCC reports are produced with the involvement of experts from the natural and social sciences. For example: "Just as there are risks of irreversible climate changes, decisions to reduce GHG emissions can require actions that are essentially irreversible. For example, once made, these long-lived, large-scale investments in low-emission technologies are irreversible. If the assumptions about future policies and the directions of climate science on which these investments are made prove to be wrong, they would become ‘stranded’ assets." . There is no reason why the risk of climate change impacts should be emphasized, but the risk of climate change policies ignored. Enescot (talk) 08:36, 2 March 2013 (UTC)
 * I've already referred to parts of the article where science academies make political recommendations. These recommendations are not explained as being political views. Nor is it explained that there are many other opinions over what climate policy should be. Enescot (talk) 08:39, 2 March 2013 (UTC)
 * If there is an example(s) of something overtly political that goes beyond agreeing with the three numbered paragraphs in the lead, we could discuss whether it would make sense to transfer that part of such statements to another article, perhaps Avoiding dangerous climate change or Politics of global warming. Such verbiage in a few quotes in no way constitutes a paradigm shift with the scope of this article or the listing criteria. NewsAndEventsGuy (talk) 12:24, 2 March 2013 (UTC)


 * I don't see what basis there is for the list which you refer to. The list you refer to of "main conclusions" on global warming is unsourced. Question 9 of the TAR Synthesis Report summarizes information from all three Working Groups, which includes an assessment of policy responses to climate change.


 * Question 1 of the Synthesis report states "Natural, technical, and social sciences can provide essential information and evidence needed for decisions on what constitutes "dangerous anthropogenic interference with the climate system." "


 * The sources I've cited are reliable, and there is an extensive literature on policy options for responding to climate change. I think a reasonable question to ask is "what do experts think should be done about climate change?" (a question also implied by Q1 above)..


 * Adding more information on policy responses would potentially lead to some overlap of content with other articles. I don't see this as a problem. Information added to this article would need to focus on how expert opinion has informed climate change policy. Enescot (talk) 06:12, 7 March 2013 (UTC)

If Scientific organganizations' policy recommendations in response to climate change is a round peg, it makes more sense to just start that article instead of trying to smash it into this earth science oriented square hole. NewsAndEventsGuy (talk) 02:02, 8 March 2013 (UTC)
 * I disagree. While it might be worthwhile to create a new article on support for climate change policies, I still think that the issue is relevant to this article. Here are a few more examples. The Doha Declaration on Climate, Health and Wellbeing is clearly policy prescriptive. Another example is this statement in the British Medical Journal  which has been signed by influential medical professionals. The British Medical Association  website suggests that doctors might want to write to their member of parliament in support of climate change policies. Enescot (talk) 06:20, 9 March 2013 (UTC)
 * I've prepared a rough draft of text that what I want to add to the article:


 * Policy responses


 * There is an extensive literature on what policies might be effective in responding to climate change. As shown above, some scientific bodies have recommended climate change policies to governments. For example, the 2001 statement by 17 national science academies endorses the Kyoto Protocol, which is an international treaty designed to reduce greenhouse gas emissions. The IPCC's mandate is to produce "policy-relevant" assessments for governments, but not to make policy recommendations.


 * One of the issues which is frequently discussed in the literature is whether or not there is a "safe" or "dangerous" level of climate change. The IPCC assessments have shown that the risks of climate change vary between different social and environmental systems. For example, coral reefs and small islands are highly vulnerable to the effects of climate change. Some systems are at risk from the climate change that has already occurred. However, the impacts of climate change may be beneficial for some human communities and non-human species.


 * Deciding which social and environmental risks are "acceptable" or "unacceptable" requires value judgements. In addition, policies taken in response to climate change may be associated with risks and costs. For example, policies designed to reduce greenhouse gas emissions will likely have an negative impact on the coal industry, and could induce unemployment in this sector.


 * Multidisciplinary assessment of climate change


 * This article mostly focuses on the views of natural scientists. However, social scientists, medics, engineers and philosophers have also commented on climate change science and policies. For example, many economists, particularly in the US, have been critical of the Kyoto Protocol. The ethical and socio-economic aspects of climate change have been assessed by IPCC Working Groups II and III.


 * Enescot (talk) 06:26, 9 March 2013 (UTC)
 * alternative. Maybe the name of this one is too generic since this one is about the earth science aspect, or whatever we should call that part of the sci that asks is it happening, what's the cause, and how much more is likely to happen?  I oppose shoehorning social sciences into this article so we have an impasse there, but we both have expressed positive comments for covering soc sci opinions elsewhere........   What is your favorite suggestion for a plan b that might get consensus if there is no consensus to greatly expand the scope of this one to include soc sci? NewsAndEventsGuy (talk) 12:08, 9 March 2013 (UTC)

I think its about time we had a section something like Enescot's above. When we started this page, the issue was the physical-science response. There's less discussion of that now, because its accepted; discussion is moving towards what-do-we-do. I think this page should stay mostly about scientific opinion, along the "policy-relevant but not policy-recommendations" kind of theme, but with some nod towards, errm, scientific opinions on policy. As you point out, various have endorsed Kyoto William M. Connolley (talk) 15:41, 9 March 2013 (UTC)


 * Agree with William: I also think the social science aspect should be covered in this article. Enescot's suggestion is a good start, I think. - Parejkoj (talk) 16:43, 9 March 2013 (UTC)
 * I've just re-read this thread from the start - I had got bored with it during its 'noises off' phase - and I think that the important things here are the title, and that this is not a top-level article. The title pins it down to 'scientific opinion', and we do have very adequate articles on the politics, the controversy, the treaties, public opinion and so on. Very often in these other articles we need to refer to 'scientific opinion' as the bedrock upon which such other weighty matters rest, and a link to this article is often how we do so. I'm sure that people working outside of Wikipedia use it in much the same way. We have long dealt with people here who want to muddy the definition of scientific opinion with 'I'm a scientist and I have an opinion' kind of nonsense. I knew that phrase long before I ever saw this article, and I sometimes have to think for a moment before I can remember what it does actually mean. I find the analogous phrase 'medical opinion' regarding a disease diagnosis helps for me. So, I don't think we want to extend this article to include economists' opinions, or political opinions of scientists, or social scientists' opinions, any more than we have allowed other mud to seep in. If we want to update this article and include a bit of present day controversy - within the remit of 'scientific opinion' - then let's look to areas of current scientific debate. Maybe, whether 2°C is really safe, what are our chances of being on course for 4 or 6°C anyway already, what levels of emissions cuts are really necessary at this stage, and will be at various points in the future if nothing else is done until then, what species are at what degree of risk, how many species have already been lost in recent times, and to what extent can we attribute any of these to climate, to what extent we can attribute recent weather disasters to it, etc. These are relevant to policy, but still remain within the realm 'scientific opinion', just not scientific opinion on the basic facts. --Nigelj (talk) 18:16, 9 March 2013 (UTC)

Whatever happens the lead to this article summarizes the mainstream scientific view and so does the lead of List of scientists opposing the mainstream scientific assessment of climate change. If they purport to summarize the mainstream view, the two leads should mirror each other. For that reason, in my opinion, it would be easier to keep these two articles restricted to the earth-science aspects, and put the scientists' policy recommendations (and opposing statements) into a separate article(s). It is possible we'd need to refine the names of these two articles if we keep them restricted to the mainstream view (and opposing view) of the EARTH SCIENCE aspects of the issue. The lead(s) to a new article(s) could easily describe the mainstream (and opposing) views on scientists' policy recommendations. I won't stand in the way, though, if no one else gives a hoot. NewsAndEventsGuy (talk) 08:29, 10 March 2013 (UTC)


 * Reply to NewsAndEventsGuy and Nigelj: There seems to be some confusion. The purpose of my suggested edit is to make the link between science and policy transparent. There already are policy recommendations contained in the article. Read the section on "Joint national science academies' statements":


 * "Climate change and sustainable energy supply are crucial challenges for the future of humanity. It is essential that world leaders agree on the emission reductions needed to combat negative consequences of anthropogenic climate change"


 * The above text is a policy interpretation/recommendation. The worst thing is that other editors do not appear to be aware of this. There is no scientific basis for making policy recommendations. It is a political issue. Why choose an 80% reduction by 2050? Why not 2040, or 2070, or 2200? The answer is that the policy target is political.


 * At least the policy literature is transparent about value judgements. The present article takes a paternalistic (non-science) approach. There is no explanation of why the science academies have made their recommendations, or of alternative policy analyses. Implicitly, it is assumed that the science academies "know best."


 * If policy isn't discussed in this article (which it already is), then it should at least refer readers on to another article. I don't particularly want to create a new article. Avoiding dangerous climate change could be expanded to include further policy prescriptions. Enescot (talk) 08:07, 29 March 2013 (UTC)


 * Option 1) Delete or move statements that are outside the scope
 * Option 2) Explicitly decide to change the scope
 * I have previously opined this should remain focused on earth/climate science and that policy recommendations by scientific orgs should go elsewhere, with a link here of course. Avoiding dangerous climate changeis a good suggestion if the decision goes that way.   NewsAndEventsGuy (talk) 10:10, 29 March 2013 (UTC)


 * I'm not comfortable with moving the policy recommendations of the science academies to avoiding dangerous climate change. In my opinion, it would be better to present a complete summary of the science academy statements in this article, including policy recommendations.


 * In my opinion, this article should mention that views on climate policy often require value judgements. The article should also mention that there are a wide range of views on climate policy. I don't think it's necessary to have an extensive discussion of these other viewpoints. Instead, this article should provide links to other articles that discuss these other viewpoints


 * My suggested addition:


 * Policy


 * See also: avoiding dangerous climate change


 * There is an extensive literature on what policies might be effective in responding to climate change. Some scientific bodies have recommended specific policies to governments. The natural and social sciences can play a role in informing an effective response to climate change. However, policy decisions may require value judgements. For example, the US National Research Council has commented :


 * "The question of whether there exists a "safe" level of concentration of greenhouse gases cannot be answered directly because it would require a value judgment of what constitutes an acceptable risk to human welfare and ecosystems in various parts of the world, as well as a more quantitative assessment of the risks and costs associated with the various impacts of global warming. In general, however, risk increases with increases in both the rate and the magnitude of climate change."


 * This article mostly focuses on the views of natural scientists. However, social scientists, medical experts, engineers and philosophers have also commented on climate change science and policies. Climate change policy is discussed in several articles: climate change mitigation, climate change adaptation, geoengineering, politics of global warming, climate ethics, and economics of global warming.


 * Enescot (talk) 08:17, 23 April 2013 (UTC)
 * Unless there are any objections, I would like to go ahead with the above edit. I think my edit should be added in-between the sections on "Synthesis reports" and "Statements by scientific organizations of national or international standing". Enescot (talk) 08:18, 12 May 2013 (UTC)

Small correction to the lede
In the lede it lists three "main conclusions of the IPCC Working Group I on global warming". However, the second reference for the third item in the list (ref #9) is "IPCC Working Group II: On balance the impacts of global warming will be significantly negative, especially for larger values of warming." Is this because IPCC Working Group II referenced the conclusions of IPCC Working Group I ? I brought this up here instead of trying to check myself because I'm not familiar with the sources I thought that someone else would probably be better suited to the task. DangerouslyPersuasiveWriter (talk) 20:44, 22 May 2013 (UTC)
 * No, it's a mistake. On a related point, the "balance of impacts" statement is not supported by the cited source (Smith et al 2001 / IPCC Working Group II) – see the above thread. Enescot (talk) 10:28, 31 May 2013 (UTC)

Unable to verify statement in lede
From the lede:


 * "On balance the impacts of global warming will be significantly negative, especially for larger values of warming."

I have been unable to verify this statement (p.958 of Smith et al., 2001). The indicator for measuring "significantly negative" impacts is not specified. According to the cited source, Smith et al, "It does not appear to be possible to combine the different reasons for concern into a unified reason for concern that has meaning and is credible" and "Aggregating impacts requires an understanding of (or assumptions about) the relative importance of impacts in different sectors, in different regions, and at different times. Developing this understanding implicitly involves value judgments". Schneider et al state "No single metric for climate impacts can provide a commonly accepted basis for climate policy decision-making".

I've looked through the IPCC Third Assessment to find a statement that most succinctly summarizes Smith et al's findings. From the Synthesis report: "Projected climate change will have beneficial and adverse effects on both environmental and socio-economic systems, but the larger the changes and the rate of change in climate, the more the adverse effects predominate" Enescot (talk) 07:50, 7 March 2013 (UTC)


 * I think anyone wanting to do forensic searching to figure out where that came from or what is based on needs to look at "list of scientists opposing...." because this section was imported as is in about March of 2012 from that other article. In particular, there is a discussion about whether to use TAR or AR4 in that arcticles archives from around Nov 2011.  NewsAndEventsGuy (talk) 01:50, 8 March 2013 (UTC)


 * People questioned that wording in the lead to List of scientists opposing the mainstream scientific assessment of global warming because of difficulty verifying it. I then replaced it with:
 * "The balance of impacts of global warming become significantly negative at larger values of warming.Working Group II: Impacts, Adaptation and Vulnerability p.958 – IPCC"
 * To date people seem to have been happy with that. I don't have a problem with Enescot's text, which says much the same thing. My version is more succinct, but you may think it is important to emphasise that there are some positive impacts. --Merlinme (talk) 17:43, 12 March 2013 (UTC)
 * Looking at the source again, I must have been paraphrasing rather than quoting. I stand by my summary of that page, but clearly there was a lot of stuff I left out. My version is essentially a combination of: "there is high confidence that with medium to high increases in temperature, net positive impacts would start to decline and eventually turn negative, and negative impacts would be exacerbated." + "Most studies of aggregate impacts find that there are net damages at the global scale beyond a medium temperature increase and that damages increase from there with further temperature increases." + "Net Negative in All Metrics" for "Aggregate Impacts" in the graphic (for four or five degree increase past 1990). You may well find a better way of summarising all that (or a better way of making the general point). --Merlinme (talk) 18:00, 12 March 2013 (UTC)
 * Thanks for your response. My main problem with the existing text is the implication that the overall impact of climate change is negative. As Smith et al/Schneider et al state, there is no satisfactory way of aggregating all the impacts of climate change together. The idea of aggregating impacts is itself problematic (e.g., see 3.3.4.3 of the SAR WGIII report, pp.99-100 ).


 * On second thought, I don't like the Synthesis Report summary. "Predominate" implies aggregation, i.e., that negative impacts will increasingly "outweigh" positive impacts. My suggestion is:


 * "Climate change will have both beneficial and adverse impacts. For higher rates and/or magnitudes of global warming, the risk of adverse impacts will tend to increase."


 * It's not a direct quote from the IPCC report, but is based on my reading of Smith et al, the technical summary (section 7.2), and the synthesis report . The idea of "beneficial" and "adverse" impacts on natural systems is rather questionable, but I've ignored that. Enescot (talk) 06:45, 19 March 2013 (UTC)
 * E, looks like that first link is broken and I wanted to look at "Smith et al/Schneider et al" to follow your argument, but I have no idea what you are referring to. NewsAndEventsGuy (talk) 10:26, 19 March 2013 (UTC)
 * I'm happy with Enescot's formulation, which is both succint & fair. -- Pete Tillman (talk) 04:57, 20 March 2013 (UTC)
 * Such judgments are pure POV until we can read the RSs. NewsAndEventsGuy (talk) 12:21, 20 March 2013 (UTC)

The existing text is well supported by the source supplied. There are no net beneficial impacts. — ArtifexMayhem (talk) 14:36, 20 March 2013 (UTC)
 * Original sentence is the more correct one, the proposed one is too ambiguous. If we take the AR4 SYR's statement just about the economic cost (other costs are equivalent):
 * Impacts of climate change are very likely to impose net annual costs, which will increase over time as global temperatures increase. ... Aggregate estimates of costs mask significant differences in impacts across sectors, regions and populations and very likely underestimate damage costs because they cannot include many non-quantifiable impacts
 * While there can be regions that will see net benefits, the overall/global/aggregated impact is negative, and increasing with higher warming. --Kim D. Petersen (talk) 17:12, 20 March 2013 (UTC)
 * BUT WAIT - there's more to this than just the single sentence.
 * First, in the lead of two different articles we summarize "the mainstream scientific consensus".  Since we set out to do the same on both articles, we need to keep the text on each being mirror images of each other.  The other article is List of scientists opposing the mainstream assessment of global warming,
 * Second, any RS other than from WG1 invites at least a discussion whether we've kicked open the doors to either (A) social science or (B) the policy recommendations of scientists..... recall that this recent focus on the mirror-image text of these two articles arose when we were talking about petitions of various sorts.
 * These observations aren't deal breakers, but let's keep an eye on how this text and any RS fits with scope of these articles in the bigger picture. NewsAndEventsGuy (talk) 21:06, 20 March 2013 (UTC)
 * No, we didn't set out to change both articles .... You did. I'm certainly not in that camp at all! --Kim D. Petersen (talk) 23:56, 20 March 2013 (UTC)
 * Baloney. The B&W letter of the text in both articles purports to summarize the main scientific points.  Where both purport to do this, and one article includes A but the other article omits A or includes B instead then we have a logic problem.  I set out to improve the project by removing a logic problem, not to unilaterally change anything.  Your apology is accepted. NewsAndEventsGuy (talk) 12:29, 21 March 2013 (UTC)
 * In both articles we set out to summarise the scientific consensus in as few words as possible. In no case is it fair to summarise climate science as "Climate change will have both beneficial and adverse impacts", as if it was a 50/50 call where, if you prefer balmy Mediterranean evenings and high crop yields, you can vote for big oil and get all the benefits. --Nigelj (talk) 12:51, 21 March 2013 (UTC)
 * Nigel, being indented under my comment makes it seem like you are replying/disagreeing/trying-to-corral to me, except I already agree with you.  What matters here, where we say in the lead that "the main science is X", as well as the other article that purports to also say in the lead that the "main science is X", is.... do the RSs support whatever we say?   You would like to say its overall effect is negative (no argument here!), but you left out what RSs you want to cite.  NewsAndEventsGuy (talk) 15:23, 21 March 2013 (UTC)
 * Do please eat your baloney alone - i'm not into italian, i like the german sausages better. [see WP:OWN and WP:CIVIL thanks]
 * They are two different articles. We don't copy things from one article to another everytime something changes in one article that happens to be similar to something the other also covers. Here is a hint: You can summarize the same thing in different ways - focusing on different nuances more suited to the issue at hand. And it has the added bonus that: it might even enlighten the reader, who reads both, more than he would have been from only reading one summary. Here is another hint: Consensus process, not unilateral process. --Kim D. Petersen (talk) 20:53, 21 March 2013 (UTC)
 * Since we are giving process hints, in two years I have never witnessed you to apologize, not ever. Maybe I missed it.
 * (1) Article A declares the mainstream consensus.
 * (2) To comply with fringe, Article B first sets out the scientific consensus
 * Any attempt to include in the "main science is X" part in one that is not in the other at least appears to be POV-driven and since you bring up consensus, I'll go all the way through DR on this, so strongly do I feel about it. Note that I am not diametrically opposed to expanding into social science, nor am I in support.   I only care that we bring it out to discuss, and generate a consensus - which I think is what you were asking for, right?  Besides never apologizing, I notice you replied with something about me instead of the content.  If I recall, you were once censured for battlegrounding.  Please stop making your replies about me.  NewsAndEventsGuy (talk) 21:01, 21 March 2013 (UTC)
 * You miss alot *g*. What you've missed here is that you are the only one insisting that the two articles must be in sync in their summaries, perhaps others agree ... but neither you nor i know that, i certainly know that i'm not in agreement (which i made clear methinks).
 * As for your A,B argument - it fails because the articles aren't about the same thing. The scientific opinion is a significantly larger issue than the nugget that we've cut it down to when deciding list criteria for the other article. Articles on Wikipedia, stand on their own merits [unless they are summary articles - which none of these are].
 * Finally: The sync. issue has little to nothing to do with your social science issue. --Kim D. Petersen (talk) 21:46, 21 March 2013 (UTC)
 * Getting back to FOC, an alternative RS for the "mostly negative" text has been offered, and this alternative as I understand it was from WG2 and is based on the social science we call economics. But not long ago, WMC added a bit of text saying that the main science summary we're using is from WG1.  That might be on the other article, but of course my position was and remains that both articles purport to say "the main science is X", and therefore A=B=A.   But of course you don't agree and the process will have to take its course.NewsAndEventsGuy (talk) 22:15, 21 March 2013 (UTC)

I was asked up-thread to name a source to support my views in this discussion. AR4 SYR (2007) has all we need. It says, among other things, "increases in drought, heat waves and floods are projected in many regions and would have mostly adverse impacts, including increased water stress and wild fire frequency, adverse effects on food production, adverse health effects, increased flood risk and extreme high sea level, and damage to infrastructure [...] climate change over the next century is likely to adversely affect hundreds of millions of people through increased coastal flooding, reductions in water supplies, increased malnutrition and increased health impacts." Looking at this, I don't really see what the problem is here - this discussion opened with Enescot looking for a source for a statement from the lede. By comparison the text he had looks too mild to me, let alone the proposed replacement about "both beneficial and adverse impacts". Of course, if we have to simultaneously talk about two articles at once, while also playing to banter about who the best sense of humour, and calculating in who has the highest likelihood of apologising first, then it does get more difficult to discuss anything. --Nigelj (talk) 23:20, 21 March 2013 (UTC)
 * I don't see anything in my acts requiring apology but I'll be glad to go to third opinion if Kim desires.
 * Going back to Enescot's opening post, your RS to support the text in question looks a lot better to me than the one Merlinme originally used, and the original text is resoundingly better than Enescots 50/50 proposal.NewsAndEventsGuy (talk) 23:27, 21 March 2013 (UTC)
 * PS I just noticed, Nigelj, you quoted from just the "extreme weather" section.  Even better IMO is to quote from the later subsection at the same RS link, titled "aggregate impacts". NewsAndEventsGuy (talk) 23:59, 21 March 2013 (UTC)
 * I actually took a bit from each of those sections and cheekily combined them with '[...]' ;-) --Nigelj (talk) 00:18, 22 March 2013 (UTC)

In response to Kim D. Petersen's and ArtifexMayhem's comments, I've already explained the deficiencies in aggregate indicators of impacts. The sentence:

"Projected climate change will have beneficial and adverse effects on both environmental and socio-economic systems, but the larger the changes and the rate of change in climate, the more the adverse effects predominate." - p32 TAR Synthesis report SPM.

from the TAR Synthesis Report. I have already quoted text from other parts of the IPCC reports:

"It does not appear to be possible to combine the different reasons for concern into a unified reason for concern that has meaning and is credible" Smith et al 2001, executive summary, p915

"Aggregating impacts requires an understanding of (or assumptions about) the relative importance of impacts in different sectors, in different regions, and at different times. Developing this understanding implicitly involves value judgments" p941 ibid

"No single metric for climate impacts can provide a commonly accepted basis for climate policy decision-making" Schneider et al 2007 p784

"Some of the current knowledge about climate change impacts, vulnerability, and adaptation is synthesized here along five reasons for concern: unique and threatened systems, global aggregate impacts, distribution of impacts, extreme weather events, and large-scale singular events. Consideration of these reasons for concern contribute to understanding of vulnerabilities and potential benefits (emphasis added) associated with human-induced climate change that can aid deliberations by policymakers of what could constitute dangerous interference with the climate system in the context of Article 2 of the UNFCCC. No single dimension is paramount (emphasis added).

Figure TS-12 presents qualitative findings about climate change impacts related to the reasons for concern. At a small increase in global mean temperature,3 some of the reasons for concern show the potential for negative impacts, whereas others show little adverse impact or risk. At higher temperature increases, all lines of evidence show a potential for adverse impacts, with impacts in each reason for concern becoming more negative at increasing temperatures. There is high confidence in this general relationship between impacts and temperature change, but confidence generally is low in estimates of temperature change thresholds at which different categories of impacts would happen." White et al 2001, p68

I can't be bothered to copy the text from the SAR. You can read it yourself here: 3.3.4.3 of the SAR WGIII report, pp.99-100

To summarize, the idea that aggregate impacts are the only way of assessing climate impacts is conceptually flawed. Aggregate indicators, like other impact metrics, provide only a partial insight into the impacts of climate change. The indicators that a particular person chooses to focus on is a subjective issue. This is the whole reason why the IPCC chose to present impacts as "reasons for concern" and "key vulnerabilities". Enescot (talk) 08:14, 22 March 2013 (UTC)


 * Reading this thread, there are some extraordinary statements. What units are you using for "mostly negative" impacts? I didn't realise that science had developed a goodandbadometer. I also find it odd that the social sciences are excluded from some parts of the article, but cited in other areas. And, of course, the social cost of carbon/monetized impacts are almost always based on a "utilitarian social welfare function," which is moral philosophy. These points should be blindingly obvious to anyone who is familiar with the IPCC assessments.


 * It's also peculiar for national science academies to be cited in support of economic assessments of impacts. Enescot (talk) 08:27, 22 March 2013 (UTC)


 * I thought it useful to refute the comment of my bias in having a "50:50 balance" between positive/negative impacts. I've already cited the TAR Synthesis report. Here's the TAR WGII SPM (pp5-6). You'll notice that 6 bullet points are provided for adverse impacts, while 5 are provided for beneficial impacts. As I've stated, the decision on how to balance these impacts is pretty arbitrary. The idea that science can decide which impacts are most "important" is utter nonsense.


 * I also think it's important to refer to this study by the Netherlands Environment Agency (p10):


 * "Examples of negative impacts dominate at summary level


 * The IPCC Working Group II Report focuses on climate impacts, adaptation and vulnerability. It was found that, in the IPCC’s highest level summary, the conclusions that were derived from the regional chapters of the Working Group II contribution to the Fourth Assessment Report single out examples of projections of negative climate-change impacts. The IPCC authors considered these to be the most relevant to policymakers. The PBL has labelled this as a ‘risk-oriented’ approach, which had been implicitly endorsed by the governments that constitute the IPCC (including that of the Netherlands). The PBL subscribes to the importance of an approach that highlights what may go wrong under unmitigated climate change, but the Working Group II Report lacked a clear explanation of the choice of approach and its consequences. Alternatively, it could be argued that policymakers should be presented with a complete picture in the Summaries for Policymakers, not just with negative examples (without suggesting that potential positive effects cancel out potential negative effects). (emphasis added)"


 * Enescot (talk) 09:01, 22 March 2013 (UTC)
 * Please do not confuse conclusions about regional impacts with global impacts - the latter we're generally confident about, while the former is very uncertain. There is no contradiction between saying: Globally impacts are going to be net negative, while we have no idea whether it will be net positive or negative for region B. --Kim D. Petersen (talk) 09:47, 22 March 2013 (UTC)

The text in question strikes me as being a statement about "aggregate" impacts. There is little point in debating amongst ourselves whether aggregate studies have merit. Instead, since the text in question is about aggregate impacts we should focus on what RSs say about aggregate impacts. Enescot seems to have raised concern about what was said in the AR4 SYR vs said in the AR4 WG2 contribution. Following some of the internal links in the AR4 SYR link provided by Nigelj leads to AR4 WG2 19.3.7; The following passage seems to be their boiled down nutshell about aggregate impacts. I have inserted their definitions of key terms of likelihood where possible.
 * "On balance, the current generation of aggregate estimates in the literature is more likely than not ("more likely than not > 50%") to understate the actual costs of climate change. Consequently, it is possible that initial net market benefits from climate change will peak at a lower magnitude and sooner than was assumed for the TAR, and it is likely ("likely >66%") that there will be higher damages for larger magnitudes of global mean temperature increases than estimated in the TAR/"

Rather tepid, IMO, especially compared to the punchy wording in the Warren paper that used to be in Global warming. It will be interesting to see where AR5 goes on "aggregate impacts". NewsAndEventsGuy (talk) 10:23, 22 March 2013 (UTC)
 * My last two posts were arrogant and hostile. If my posts have offended any other editors, I am sorry. In the future, I will try and behave in a more civilized way. Enescot (talk) 07:43, 24 March 2013 (UTC)
 * I want to re-emphasize that none of the sources cited by other editors supports the following statement in the lead (labelled (A) for reference):


 * (A) "On balance the impacts of global warming will be significantly negative, especially for larger values of warming."


 * As I've already stated, the above statement contradicts the view that impacts cannot be reduced down to a single indicator (Smith et al 2001, p.915;Schneider et al 2007 p784;White et al 2001, p68).


 * I do not agree with NewsAndEventsGuy's point about sticking with aggregate impacts. As I've already explained, aggregate measures, such as GDP, do not accurately convey the full range of impacts.


 * There is some text from the TAR synthesis report (p.142, para 9.28) which partly supports (A):


 * "For mean temperature increases over a few ºC relative to the year 1990, impacts are predominantly adverse, so net primary benefits of mitigation are positive. A key uncertainty is the net balance of adverse and beneficial impacts of climate change for temperature increases less than about a few ºC. These averages conceal wide regional variations"


 * The above text does not appear to be supported by the full Working Group II or III reports. It appears to be based on the "burning embers" diagram, which is dated and was rejected in AR4.


 * I've drafted a replacement for (A) which I think is fair and balanced. It is a quote from the US National Research Council document "Advancing the Science of Climate Change – Report in Brief" (p.2):


 * "(B) Human-caused climate changes and impacts will continue for many decades and in some cases for many centuries. The magnitude of climate change and the severity of its impacts will depend on the actions that human societies take to respond to these risks."


 * An alternative could be to replace all 3 numbered points in the lead with the following text (ibid, p.1):


 * (C) "A strong, credible body of scientific evidence shows that climate change is occurring, is caused largely by human activities, and poses significant risks for a broad range of human and natural systems"


 * Enescot (talk) 09:53, 8 April 2013 (UTC)
 * The basic, intermediate and advanced tabs here are all very well cited. --Nigelj (talk) 19:48, 8 April 2013 (UTC)


 * Enescot, I'm not sure we're on the same page. You seem to want to talk about the "full range" of impacts, and you seem to say that if we talk about "aggreage impacts" we will - by definition - leave stuff out.  However, the IPCC definition of "aggregate impact" seems to put everything, good-bad-ugly, into one single bucket.  IPCC glossary says: "Aggregate impacts Total impacts integrated across sectors and/or regions. The aggregation of impacts requires knowledge of (or assumptions about) the relative importance of impacts in different sectors and regions. Measures of aggregate impacts include, for example, the total number of people affected, or the total economic costs."  In light of this definition, please identify RSs that the "full range of impacts" in excess of IPCC's definition of "aggregate impacts".  It seems to me that IPCC has defined an infinite set, and you claim that there are RSs which talk about an even bigger infinite set.   I never was any good at calculus so help me out please with RS citation why "aggregate impacts" doesn't include everything in its definition.  (The immaturity of that area of science and its ability to capture everything is a different issue) NewsAndEventsGuy (talk) 20:10, 8 April 2013 (UTC)
 * The cited source does not support statement (A). In fact, statement (A) implicitly contradicts Smith et al (2001) and Schneider et al (2007). The website "Skeptical Science" does not, by any means, represent a scientific consensus on climate change. My original suggested text was based on:


 * (1.1) "Projected climate change will have beneficial and adverse effects on both environmental and socio-economic systems, but the larger the changes and the rate of change in climate, the more the adverse effects predominate."


 * which comes from the TAR Synthesis Report Summary for Policymakers Question 9 Table SPM-3: Robust findings and key uncertainties, p.32. Table SPM-3 draws together all of the key findings from the IPCC TAR.


 * The SPM was approved in line-by-line detail by delegates from most of the world's governments. (1.1) was deliberately written to summarize the findings of the TAR Working Group II report. (1.1) is, by far, a more widely accepted summary of impacts than (A). (A) was written by a Wikipedia editor (Merlinme).


 * (B) and (C) were deliberately written to provide a short summary of climate change impacts. Again, (B) and (C) were written by experts.


 * I think Merlinme's text is not supported by Smith et al (2001). In my view, Merlinme's text does not accurately summarize the impacts of climate change. By contrast, (1.1), (B) and (C) are all direct quotes from authoritative sources.


 * In response to NewsAndEventsGuy's comment, I have already referred to several sources which explain the deficiencies of aggregate indicators. I have cited these sources and quoted from them. The IPCC do not rely on aggregate measures of impacts. Their top-level summaries emphasize the diversity of climate change impacts, e.g., . The reports cover how impacts are distributed, use multiple metrics, and look at the issue from different ethical and political perspectives, e.g., Rawlsian and utilitarian social welfare functions (consequentialism), and social justice. For example, most concepts of justice support the view that you should not impose damages on other people. This is completely ignored in economic assessments based on utilitarianism. Economic assessments largely ignore impacts on indigenous peoples, and give special weighting to the preferences of the rich. The preferences of future generations and non-human species are not included in these analyses. The only way of including preferences is through money, which is a rather narrow and cynical view of human nature. Another example of the limitations of aggregation is the impact of climate change on food production. The fact that food production may increase in some regions does not "offset" damages in other regions which face reduced food security. Enescot (talk) 08:40, 9 April 2013 (UTC)

Unless other editors have further objections, I would like to replace statement (A) in the lead, i.e.,:


 * (A) "On balance the impacts of global warming will be significantly negative, especially for larger values of warming."

I have already suggested a replacement for (A):


 * "(B) Human-caused climate changes and impacts will continue for many decades and in some cases for many centuries. The magnitude of climate change and the severity of its impacts will depend on the actions that human societies take to respond to these risks."

(B) is a quote from the US National Research Council document "Advancing the Science of Climate Change – Report in Brief" (p.2).

In my opinion, the lead should also be updated in view of the IPCC Fourth Assessment Report.

Suggested revision:


 * [...] National and international science academies and scientific societies have assessed the current scientific opinion, in particular on recent global warming. These assessments are generally consistent with the conclusions of the Intergovernmental Panel on Climate Change (IPCC).


 * There is a broad scientific consensus on the following points:


 * -Warming of the climate system is unequivocal, as evidenced by increases in global average air and ocean temperatures, the widespread melting of snow and ice, and rising global average sea level (IPCC, 2007).
 * -Most of the global warming since the mid-20th century is very likely due to human activities (IPCC, 2007).
 * -"Human-caused climate changes and impacts will continue for many decades and in some cases for many centuries. The magnitude of climate change and the severity of its impacts will depend on the actions that human societies take to respond to these risks" (US National Research Council, 2010).

Enescot (talk) 08:28, 23 April 2013 (UTC)
 * Caution, let's not mislead readers into thinking the RSs say we have centuries to waffle about taking action. If we report the scientists' time scale of "centuries" in terms of impacts, I think we should report the scientists' time scale in terms of needed mitigation policy, and that the bang of mitigation dollars spent now will go a lot further than later.  NewsAndEventsGuy (talk) 12:07, 23 April 2013 (UTC)
 * What part of the text below says that "we have centuries to waffle about taking action"?


 * "Human-caused climate changes and impacts will continue for many decades and in some cases for many centuries. The magnitude of climate change and the severity of its impacts will depend on the actions that human societies take to respond to these risks"


 * I'm also confused over your assertion of scientists urging for near-term emissions reductions. It was my understanding that you wish to exclude discussion of policy from this article. This appears to contradict your current viewpoint.


 * The issue of the mitigation is partly one of politics. As such, the timing and extent of near-term emissions reductions is partly a political decision. While it is true that some natural scientists support stringent near-term emissions reductions, there is no "scientific consensus" on this issue. Indeed, various arguments can be made in favour of stringent or modest near-term abatement (IPCC TAR WG3, technical summary, p70). Enescot (talk) 08:02, 25 April 2013 (UTC)
 * Re (A), it is implicit, obviously. A statement that changes will happen over "centuries" is prone to unconscious communication of the idea that there is no immediate need for mitigation
 * Re (B), there is no inconsistency.  True I previously said that I don't think including policy here is a good approach but I also said I would not stand in the way if everyone else wants to do that.  Indeed, I have been a lone voice.  So my more recent comments are entirely consistent with my promise to respect consensus about including policy here.
 * Re (C), so...... what is the scientific consensus about policy anyway?

NewsAndEventsGuy (talk) 11:19, 25 April 2013 (UTC)
 * I don't agree with (A). However, if you have a suggestion for addressing this problem, then perhaps we can discuss it? As an alternative, I'd be happy to use the text that I've previously suggested:


 * (i) "Projected climate change will have beneficial and adverse effects on both environmental and socio-economic systems, but the larger the changes and the rate of change in climate, the more the adverse effects predominate."


 * Or perhaps this?


 * (ii) "Human-induced climate change poses significant risks for a broad range of human and natural systems" (based on the US National Research Council document "Advancing the Science of Climate Change – Report in Brief", p.1).


 * On (B), thanks for the clarification. My impression was mistaken.


 * On (C), I can only go on what the IPCC reports have said (e.g., IPCC TAR SYR Question 9, pp.141-145; IPCC AR4 SYR Summary for policymakers, pp.14-22. In my view, the lead should mention something about climate change policies, e.g., the benefits of reducing emissions. Enescot (talk) 06:11, 28 April 2013 (UTC)
 * I'm afraid I still fail to see how suggested option (B) is compatible with the following from AR4 WG2: "Taken as a whole, the range of published evidence indicates that the net damage costs of climate change are likely to be significant and to increase over time." The implication I get from (B) is that the impacts of climate change will take decades or centuries to become apparent, so that, because that represents plenty of time for human society to respond by taking various actions, it's impossible to know now the severity of these impacts. (B: "Human-caused climate changes and impacts will continue for many decades and in some cases for many centuries. The magnitude of climate change and the severity of its impacts will depend on the actions that human societies take to respond to these risks.") I'm not at all happy with those implications when they are compared to the wording in AR4. --Nigelj (talk) 19:51, 28 April 2013 (UTC)
 * The following (labelled for reference):


 * (A1) "Taken as a whole, the range of published evidence indicates that the net damage costs of climate change are likely to be significant and to increase over time."


 * is based on a highly dubious set of value-laden assumptions made by economists (the "social cost of carbon", SCC) . The problems with SCC estimates are summarized in the IPCC summary for policymakers :


 * "The large ranges of SCC are due in the large part to differences in assumptions regarding climate sensitivity, response lags, the treatment of risk and equity, economic and non-economic impacts, the inclusion of potentially catastrophic losses, and discount rates (...)


 * It is virtually certain that aggregate estimates of costs mask significant differences in impacts across sectors, regions, countries and populations. In some locations and among some groups of people with high exposure, high sensitivity and/or low adaptive capacity, net costs will be significantly larger than the global aggregate"


 * See also Azar 1998.


 * In my opinion, the SCC should be not emphasized over others measures of impacts, e.g., the distributional effects of climate change, impacts on food production and biodiversity, and so on.


 * I do not agree with your criticisms of (B). However, If you have any other suggestions for possible alternatives, then perhaps we could discuss them. I've already suggested two alternatives to (B) in my previous post. In my opinion, A1 is not a good alternative. Enescot (talk) 07:55, 29 April 2013 (UTC)
 * It now seems that you are trying to do two things simultaneously. One is to add content to this article about social, economic, political, and policy matters (and I have already commented above that I don't see that this is relevant to an article whose title starts 'scientific opinion...' [18:16, 9 March 2013 (UTC)]). It appears now that at the same time you are being fairly insistent that such content should be as vague and non-committal as possible. I do not think that scientific opinion is in much doubt that climate change is and will have overall negative effects on droughts and floods, marine and terrestrial ecosystems, human food supply, malnutrition, current species extinctions, deserticiation, and so on. When we find such conclusions in AR4 etc, you say that economists don't like them, and have tried to pick holes in them. I don't think you're easily going to get top-level lede text into an article about scientific opinion on climate change that says that economists and politicians are still hoping that someone will invent something soon enough that fixes it all. Of course they are; they are wrong; and the science still stands. --Nigelj (talk) 10:52, 29 April 2013 (UTC)

Any problem just changing the article text under discussion to a verbatim quote from IPCC TAR (2001) WG2 TechSum pg 68?
 * "At higher temperature increases, all lines of evidence show a potential for adverse impacts, with impacts in each reason for concern becoming more negative at increasing temperatures. There is high confidence in this general relationship between impacts and temperature change..."

NewsAndEventsGuy (talk) 21:40, 30 April 2013 (UTC)
 * Reply to Nigelj: I do not see the basis for your comment. The text that you've suggested (I'll continue to refer to this as A2):


 * (A2) "Taken as a whole, the range of published evidence indicates that the net damage costs of climate change are likely to be significant and to increase over time."


 * refers to the following sections of the AR4 WG2 report: T20.3, 20.6, F20.4. Table 20.3 is a list of estimates of the social cost of carbon. This is an economic measure of climate change impacts. It is a flawed measure of impacts:


 * "Some argue that it is necessary to specify more precisely why certain impacts are undesirable and to comprehensively itemize the economic consequences of climate change in monetary terms. The credibility of such efforts has often been questioned, given the uncertainty surrounding climate impacts and the efficacy of societal responses to them, plus the controversial meaning of a monetary metric across different regions and generations"


 * I'll refer to some other quotes again:


 * "It does not appear to be possible to combine the different reasons for concern into a unified reason for concern that has meaning and is credible" Smith et al 2001, executive summary, p915


 * "No single metric for climate impacts can provide a commonly accepted basis for climate policy decision-making" Schneider et al 2007 p784


 * You state that:


 * "I do not think that scientific opinion is in much doubt that climate change is and will have overall negative effects on droughts and floods, marine and terrestrial ecosystems, human food supply, malnutrition, current species extinctions, deserticiation, and so on. When we find such conclusions in AR4 etc, you say that economists don't like them, and have tried to pick holes in them."


 * I've already asked this question: what units you are using to measure positive or negative impacts? The latter statement about economists "picking holes" is odd. It is you who are emphasizing economic (monetized) assessments of climate change impacts. The statements that I've suggested apply to risk-based assessments of climate change impacts. An advantage of risk assessments is that they do not need to be converted into a common unit.


 * You have stated:


 * "It appears now that at the same time you are being fairly insistent that such content should be as vague and non-committal as possible."


 * My suggested text is


 * (1.1) "Projected climate change will have beneficial and adverse effects on both environmental and socio-economic systems, but the larger the changes and the rate of change in climate, the more the adverse effects predominate."


 * As I've already stated, this is a "robust finding" of the TAR Synthesis Report SPM (p.32). (1.1) is part of the TAR Synthesis report's top-level summary of climate change impacts. (1.1) is based on the TAR's "reasons for concern":


 * "The impacts of climate change will be more severe the greater the cumulative emissions of greenhouse gases (medium confidence). Climate change can have beneficial as well as adverse effects, but adverse effects are projected to predominate for much of the world. The various effects of climate change pose risks that increase with global mean temperature. Many of these risks have been organized into five reasons for concern: threats to endangered species and unique systems, damages from extreme climate events, effects that fall most heavily on developing countries and the poor within countries, global aggregate impacts, and large-scale high-impact events (see Box 3-2 and Figure 3-1). The effects of climate change on human health, ecosystems, food production, water resources, small islands and low-lying coastal regions, and aggregate market activities are summarized below. However, note that future changes in the frequency or intensity of extreme events have not been taken into account in most of these studies (see also Question 4)." p67


 * (1.1) is consistent with my reading of AR4 :


 * "General conclusions include the following [19.3].


 * -Some observed key impacts have been at least partly attributed to anthropogenic climate change. Among these are increases in human mortality, loss of glaciers, and increases in the frequency and/or intensity of extreme events.
 * -Global mean temperature changes of up to 2°C above 1990-2000 levels (see Box 19.2) would exacerbate current key impacts, such as those listed above (high confidence), and trigger others, such as reduced food security in many low-latitude nations (medium confidence). At the same time, some systems, such as global agricultural productivity, could benefit (low/medium confidence).
 * -Global mean temperature changes of 2 to 4°C above 1990-2000 levels would result in an increasing number of key impacts at all scales (high confidence), such as widespread loss of biodiversity, decreasing global agricultural productivity and commitment to widespread deglaciation of Greenland (high confidence) and West Antarctic (medium confidence) ice sheets.
 * -Global mean temperature changes greater than 4°C above 1990-2000 levels would lead to major increases in vulnerability (very high confidence), exceeding the adaptive capacity of many systems (very high confidence).
 * -Regions that are already at high risk from observed climate variability and climate change are more likely to be adversely affected in the near future by projected changes in climate and increases in the magnitude and/or frequency of already damaging extreme events."

The alternative texts that I've suggested are based on a report by the US National Research Council. I chose these texts because they feature prominently in the US NRC summary. To me, this indicates that they were written to be brief summaries of climate change impacts. Enescot (talk) 09:09, 8 May 2013 (UTC)
 * I assume we're still discussing the original point, that you are unable to verify the statement in the lede, that "On balance the impacts of global warming will be significantly negative, especially for larger values of warming." First, I think it's time to move on from TAR - that was 2001. Nonetheless, I can see a crucial difference in phrasing. You want to say "climate change will have beneficial and adverse effects" with apparent equal weight until much later in the long sentence. TAR started by talking about severity (a negative term) and then said "Climate change can have beneficial as well as adverse effects" (my emph) before expanding the adverse ones to refer to "much of the world". Even based on this pre-2001 research, that is much less equivocal than your suggestion. Second, looking at AR4, they list "human mortality, loss of glaciers, and increases in the frequency and/or intensity of extreme events" as currently occurring (pre 2007) and have "high confidence" that those will be "exacerbated" by less than 2°C rise. When you compare this with "low/medium confidence" that "agricultural productivity could benefit", you do not need a degree in philosophy to reason that the balance is negative before you start to look at more severe temperature rises: people are dying, but farmers' profit margins may increase slightly? There'll be more food, and less people to eat it? Of course, for 2 to 4°C things are much worse, and in fact that little boost to agricultural productivity is replaced by widespread loss of biodiversity, decreasing global agricultural productivity and widespread deglaciation (all with high confidence) (my emph again). Of course, nobody seriously expects global warming to remain below 2°C after recent political failures. I do not see how any of this becomes the basis for an equivocal top-level statement predicting definite "beneficial and adverse effects", no matter how it is modified by later text. --Nigelj (talk) 22:56, 8 May 2013 (UTC)


 * Reply to NewsAndEventsGuy: I agree with the gist of your suggested edit. Your edit would need to briefly explain what the "reasons for concern" are. In my reply to Nigelj (see below), I've suggested an alternative compromise edit. Enescot (talk) 08:50, 12 May 2013 (UTC)
 * reply to Nigelj: I suggest a compromise. I've put together some draft text that I would like to discuss. It includes information on the social cost of carbon, as well as some additional information from AR4:


 * - The benefits and costs of climate change for human society will vary widely by location and scale. Some of the effects in temperate and polar regions will be positive and others elsewhere will be negative. Overall, however, net effects are more likely to be strongly negative under larger or more rapid warming. (Based on AR4, Technical summary, Box TS.5. The main projected impacts for systems and sectors)
 * - "[...] the range of published evidence indicates that the net damage costs of climate change are likely to be significant and to increase over time" (AR4 WG2 SPM: Magnitudes of impact)
 * - "The resilience of many ecosystems is likely to be exceeded this century by an unprecedented combination of climate change, associated disturbances (e.g. flooding, drought, wildfire, insects, ocean acidification) and other global change drivers (e.g. land-use change, pollution, fragmentation of natural systems, over-exploitation of resources)" (AR4 Synthesis report, 3.3.1 Impacts on systems and sectors)


 * Enescot (talk) 08:50, 12 May 2013 (UTC)


 * I can't see the point of all that. This article is about the scientific side and when they said bad they simply meant for instance where loss of species is considered bad rather than placing an economic value on them. The economics of climate change is covered in Economics of global warming. For all we know in a hundred years they'll say what a wonderful thing it is rather like they have people going back to work in a war, or not having food was a good thing as people were healthier. This article should just have one simple statement summarizing what they said the overall effect would be in the latest IPCC report and just leave it at that. The main point of this article is about the scientific consensus that global warming is actually happening. I believe the current statement with the context that it is a conclusion of the IPCC and the citations is perfectly okay and needs no change. Dmcq (talk) 15:50, 15 May 2013 (UTC)
 * Thanks for your reply. I've been quite clear in explaining and sourcing my arguments. As for your view about the scope of this article, I disagree. The IPCC takes a comprehensive approach in its assessment of climate change. This includes observed climate change, its impacts, and policy responses. This comprehensive approach is also reflected other authoritative sources, such as the 2005 joint-statement by the science academies of the G8, plus Brazil, China and India, and the Doha Declaration on Climate, Health and Wellbeing . Enescot (talk) 08:42, 19 May 2013 (UTC)
 * I would point out that this is not an IPCC article, this is Wikipedia. As such, Wikipedian standards regarding the overall scope of the given topic are best applied. 72.38.238.66 (talk) 19:42, 22 May 2013 (UTC)
 * My original comment was that this statement (A):


 * "On balance the impacts of global warming will be significantly negative, especially for larger values of warming"


 * is not supported by the source. I have already provided an explanation of why this is the case. If you can find a flaw in my reasoning, then please explain it to me. The comments of Dmcq are not consistent with the source material, e.g.,


 * "This article is about the scientific side and when they said bad they simply meant for instance where loss of species is considered bad rather than placing an economic value on them" - Dmcq


 * Smith et al (2001) were quite clear in explaining their risk assessment. They used various metrics to assess climate change impacts. As far as I'm aware, they did not make any statement that is consistent with (A). In fact, they stated:


 * "It does not appear to be possible to combine the different reasons for concern into a unified reason for concern that has meaning and is credible." - p.915


 * The TAR Synthesis report and AR4 do not support (A). AR4's reference to "net damages" is based on estimates of the social cost of carbon, which is an economic measure of impacts.


 * I've already cited authoritative scientific sources that comment on impacts and policy, e.g.,:


 * "The projected changes in climate will have both beneficial and adverse effects at the regional level, for example on water resources, agriculture, natural ecosystems and human health. The larger and faster the changes in climate, the more likely it is that adverse effects will dominate.


 * [...] We urge all nations, in the line with the UNFCCC principles, to take prompt action to reduce the causes of climate change, adapt to its impacts and ensure that the issue is included in all relevant national and international strategies. As national science academies, we commit to working with governments to help develop and implement the national and international response to the challenge of climate change." - 2005 joint-statement by the science academies of the G8, plus Brazil, China and India


 * "We call on all governments to [...] agree at the UNFCCC negotiations in Copenhagen to adopt a long-term global goal and near-term emission reduction targets that will deliver an approximately 50% reduction in global emissions from 1990 levels by 2050" - 2009 joint-statement by the science academies of the G8, plus Brazil, China, India, Mexico and South Africa


 * By comparison, other editors have not provided any reason why "scientific opinion" should only cover observed climate change and its attribution. Perhaps you can explain to me why the IPCC's integrated approach is wrong, or why the views of major science academies do not qualify as scientific opinion? I should note that the article already discusses policy:


 * "Among other actions, the declaration urges all nations to “(t)ake appropriate economic and policy measures to accelerate transition to a low carbon society and to encourage and effect changes in individual and national behaviour."" - from the article


 * Enescot (talk) 08:55, 23 May 2013 (UTC)

After edit
I see that Enescot has gone ahead and changed the lede, despite the long discussion above. I strongly disagree with the introduction of the text "The benefits and costs of climate change for human society will vary widely by location and scale.[7] Some of the effects in temperate and polar regions will be positive and others elsewhere will be negative.[7]" into the lede. I see that it is meant to be a home-made summary of AR4 TS.4.1. Rather than summarising work for ourselves, why not look a few pages further on to TS.4.3 where the section is summarised in a table? Here we see that in the range 0 - 2 °C rise, in mid to high latitudes, the IPCC expect an increase in crop productivity for some cereal crops. Everywhere else in that table we see nothing but negative effects for the same rise. What right do we have to emphasise this small and temporary rise in profitability for some cereal farmers when set against the following worldwide: There is room to mention the possible gains for cereal farmers in the body of the article, with proper context, but in the lede we must present the bigger picture. --Nigelj (talk) 18:57, 4 June 2013 (UTC)
 * 1) Up to 2 billion additional people suffering increased water stress
 * 2) Increasing amphibian extinction
 * 3) Most corals bleached
 * 4) Increasing wildfire risks
 * 5) Decrease in some cereals in low latitudes
 * 6) Increased damage from floods and storms
 * 7) Up to an additional 3 billion people at risk of coastal flooding each year
 * 8) Increased burden from malnutrition, diarrhoeal, cardio-respiratory and infectious diseases
 * 9) Increased morbidity and mortality from heatwaves, floods and droughts
 * This is not a "home-made" summary. In Box TS.5, the first bullet-point of the section on "Industry, settlement and society" states:


 * "Benefits and costs of climate change for industry, settlement and society will vary widely by location and scale. Some of the effects in temperate and polar regions will be positive and others elsewhere will be negative. In the aggregate, however, net effects are more likely to be strongly negative under larger or more rapid warming. ** N"


 * The double asterisks (**) mean that this statement is made with "high confidence". My minor alteration is in brackets:


 * "Benefits and costs of climate change for [human] society will vary widely by location and scale. Some of the effects in temperate and polar regions will be positive and others elsewhere will be negative. In the aggregate, however, net effects are more likely to be strongly negative under larger or more rapid warming."


 * Also note this summary:


 * "The projected changes in climate will have both beneficial and adverse effects at the regional level, for example on water resources, agriculture, natural ecosystems and human health. The larger and faster the changes in climate, the more likely it is that adverse effects will dominate. - 2005 joint-statement by the science academies of the G8, plus Brazil, China and India


 * Enescot (talk) 09:13, 11 June 2013 (UTC)
 * It is an extensive quote from one bullet point on a page with 65 bullet points. Incidentally, from one of only six that mentions 'benefits' or 'beneficial' (e.g. "The negative impacts of climate change on freshwater systems outweigh the benefits.") Maybe I should have said 'cherry-picked'. --Nigelj (talk) 16:33, 11 June 2013 (UTC)
 * I disagree. In support of my edit, I've referred to the top-level summary from the TAR (SPM, p.32) and the 2005 joint-statement made by the science academies of the G8, Brazil, China and India. As a second option, I have suggested an edit based on a top-level summary by the US National Research Council . I have not found your criticisms of these summaries convincing.


 * Another alternative would be to summarize the list of "robust findings and key uncertainties" from AR4 Synthesis report . According to the 2008 joint-statement made by the science academies of the G8+5 :


 * ''"Key vulnerabilities [to climate change] include water resources, food supply, health, coastal settlements and some ecosystems (particularly arctic, tundra, alpine, and coral reef). The most sensitive regions are likely to include the Arctic, Africa, small islands and the densely populated Asian mega-deltas.


 * As the concentration of greenhouse gases increases, these impacts become more severe and spread both geographically and sectorally"


 * The above text is consistent with AR4's "robust findings and key uncertainties". Enescot (talk) 10:49, 18 June 2013 (UTC)