User:EmilyDUOregon/sandbox

Assigning a Topic:

As I have been searching for topics to focus on, I am most interested in deglaciation, and have found that the section already written about this on Wikipedia is vey minimal and basic. Therefore, I find that it would be an appropriate topic to assign myself and contribute to. There is much information that I could add to this topic, such as much more extensive information about the causes and affect of deglaciation, also add much more detail about the Last Glacial Maximum, as this section is severely lacking much data. I could also add much more detailed information about the landforms we see today, and how these were formed due to deglaciation. Much of the stuff that I felt like the article was lacking was mentioned in our first assignment, "critiquing an article". I found some sources of relevant information that would be useful when contributing to this article. I will post these below, and also on the articles talk page.

- "Global climate evolution during the last deglaciation" by Clark et al.

- "Younger Dryas cooling and the Greenland climate response to CO2" - by Liu et al. (As Greenland is discussed in the article, but not extensively)

- "Synchronous centennial abrupt events in the ocean and atmosphere during the last deglaciation" by Chen et al.

- "Deglaciation" by Bridges, E. M

- "Deglaciation of Fennoscandia" by Stroeven et al. (It may be interesting to mention this along side the topic of Greenland)

Bibliography:

Bridges, E. M. "Deglaciation." Transactions of the Institute of British Geographers 38 (1966): 203-04. Web.

Chen, Tianyu, Laura F Robinson, Andrea Burke, John Southon, Peter Spooner, Paul J Morris, and Hong Chin Ng. "Synchronous Centennial Abrupt Events in the Ocean and Atmosphere during the Last Deglaciation." Science (New York, N.Y.) 349.6255 (2015): 1537-41. Web.

Clark, Peter U., Jeremy D. Shakun, Paul A. Baker, Patrick J. Bartlein, Simon Brewer, Ed Brook, Anders E. Carlson, Hai Cheng, Darrell S. Kaufman, Zhengyu Liu, Thomas M. Marchitto, Alan C. Mix, Carrie Morrill, Bette L. Otto-Bliesner, Katharina Pahnke, James M. Russell, Cathy Whitlock, Jess F. Adkins, Jessica L. Blois, Jorie Clark, Steven M. Colman, William B. Curry, Ben P. Flower, Feng He, Thomas C. Johnson, Jean Lynch-Stieglitz, Vera Markgraf, Jerry Mcmanus, Jerry X. Mitrovica, Patricio I. Moreno, and John W. Williams. "Global Climate Evolution during the Last Deglaciation." Proceedings of the National Academy of Sciences of the United States of America 109.19 (2012): E1134. Print.

Liu, Zhengyu, Anders E. Carlson, Feng He, Esther C. Brady, Bette L. Otto-Bliesner, Bruce P. Briegleb, Mark Wehrenberg, Peter U. Clark, Shu Wu, Jun Cheng, Jiaxu Zhang, David Noone, and Jiang Zhu. "Younger Dryas Cooling and the Greenland Climate Response to CO₂." Proceedings of the National Academy of Sciences of the United States of America 109.28 (2012): 11101-1104. Web.

Stroeven, Arjen P., Et Al. "Deglaciation of Fennoscandia." Quaternary Science Reviews 147 (2016): 91-121. Science Direct. Web. 04 May 2017.

Improving the existing “Deglaciation Article”:

As mentioned previously, this article lacks a lot of useful information pertaining to Deglaciation, and would benefit greatly from some added material. (Below is a rough draft of some of the topics I will be expanding on and adding to for my final article)

This article has a very short introduction on deglaciation, which could be improved upon significantly. The current introduction is relatively short, and only discusses the absolute basics of what deglaciation is, but it would be helpful for readers if a much more in-depth, descriptive paragraph were provided.

There is much in-depth information and data available in relation to the Last Glacial Maximum (LGM), which this article does not discuss in much detail. Beginning with some general information about the LGM, which will add to the beginning paragraph of the already existing article, then creating a section that focuses on a specific place and the changes experienced in that place, during and since the LGM, the focus being on north America.

Deglaciation overview:

Around much of Earth, deglaciation has been occurring as a result of climate change, brought on by increased exploitation of natural resources. This exploitation has many consequences, such as the release of greenhouse gases into the atmosphere. When greenhouse gases, such as carbon dioxide and methane, are released into the atmosphere. Many scientists have linked glacier retreat, and glacier disappearance, deglaciation, to the Industrial Revolution. The Industrial Revolution began in the late mid 1700’s, and encouraged the growth of electricity production, through the use of petroleum, coal and other fossil fuels. Such fossil fuels release the carbon dioxide, and methane into the atmosphere, at an increase rate of 40% over the past 200 years. When released into the atmosphere, the gases absorb much of the heat being radiated by the surface of Earth. Through this absorption, the Earth begins to slowly heat up. Not only do greenhouse gases cause deglaciation, but also farming, which creates soot and dust, and the burning of forests has also resulted in many of the early glacier retreats and disappearances in Europe in the later 1800’s, during the last glacial maximum.

The previous deglaciation that took place on the earth did so between approximately 22ka until 11.5ka. This took occurred when there was an annual mean atmospheric temperature on the earth that increased by roughly 5°C, which was also accompanied by regional high-latitude warming that exceeded 10°C. This was also followed by noteworthy deep-sea and tropical-se warming, between about 1-2°C (deep-sea) and 2-4°C (tropical sea). Not only did this warming occur, but the global hydrological budget also experienced noticeable changes and regional precipitation patters changed. As a result of all of this, the worlds main ice sheets, including the ones located in Eurasia, North America and parts of the Antarctic Ice Sheets melted. As a consequence, sea levels rose roughly 120 metres). These processes did not occur steadily, and they also did not occur at the same time.

(I think the deglaciation overview and effects section should just be a single section, as they contain very similar information and its difficult to distinguish between the two as separates, but I do not want to remove a section that someone else has added. So, I'm just going to add "effects" to the "causes and effects" section, as this is a separate topic that needs some work as it is lacking much necessary information. I am going to relate the effects of deglaciation to the Laurentide ice sheet overall, as finding just general effects is not easy, as scientific studies tend to be as specific as they possibly can be. So I have added another heading about the Laurentide ice sheet underneath the heading of effects of deglaciation).

The Last glacial Maximum:

Between roughly 19ka, the end of the Last Glacial Maximum (or LGM) to 11ka, which was the early Holocene, the climate system experienced drastic transformation. Much of this change was occurring at an astonishing rate, as the earth was dealing with the end of the last ice age. Changes in insolation was the principal reason for this drastic global change in climate, as this was linked with several other changes globally, from the alteration of ice sheets, to the concentration of greenhouse gases fluctuating, and many other feedbacks that resulted in distinct responses, both globally and regionally. Not only were ice sheets and greenhouse gases experiencing alteration, but also additionally to this, there was sudden climate change, and many occurrences of fast, and sizeable rising of sea level. The melting of the ice sheets, along with the rising sea levels did not happen until after 11ka. Nonetheless, the globe had arrived at its present interglacial period, where climate is comparatively constant and stable, and greenhouse gas concentrations exhibit near pre-industrial levels. This data is all available due to studies and information gathered from proxy records, both from the terrestrial and ocean, which illustrates overall global patterns of changes in climate whilst in the period of Deglaciation.

During the Last Glacial Maximum (LGM), there were apparent low atmospheric concentration of Carbon Dioxide (CO2), which was believed to be as a result of larger containment of carbon in the deep ocean, via the process of stratification within the Southern Ocean. These Southern Ocean deep waters contained the least δ13C, which consequently resulted in them being the location with the greatest density, and most salt content during the LGM. The discharge of such sequestered carbon was perhaps a direct outcome of the deep Southern Ocean overturning, driven by heightened wind-driven upwelling, and sea-ice retreat, which are directly correlated to the warming of the Antarctic, and also coinciding with the cold events, the Oldest and Younger Dryas, in the north.

Throughout the LGM in North America, the east was populated by cold-tolerant conifer forests, while the southeast and northwest of the United States sustained open forests in locations that have closed forests today, which suggests that during the LGM temperatures were cooler and overall conditions were much drier than those that we experience today. There is also indication that the southwest of the United States was much wetter during the LGM compared to today, as there was open forest, where today we see desert and steppe. In the United States, the general variation of vegetation implies an overall fall in temperatures of (at minimum 5°C), a shift of the westerly storm tracks to the south, and a very steep latitudinal temperature gradient.

Next, the topic of the effects of Deglaciation should be expanded on, as the current article only provides links to this. There will be some overall expansion in relation to the landforms that are created as a result of Deglaciation. The main landforms that will be focused on include moraines, eskers, kettles, kames, drumlins, thermokarsts, tunnel valleys, proglacial lakes and subglacial channels. Still more to add, this is just a rough draft of some of the topics I will add or expand upon from the current “deglaciation” article.

Causes and Effects:

Focus on Laurentide Ice Sheet:

Throughout the Pleistocene Epoch, the Laurentide Ice sheet covered the vast majority of North America and Canada, with over 5,000,000 square miles of coverage. The Laurentide ice sheet was 10,000 feet deep in some areas, and reached as far south as 37°N. EmilyDUOregon (talk) 01:22, 13 June 2017 (UTC)

Cycles of deglaciation are driven by various factors, with the main driver being changes in incoming summer solar radiation, or insolation, in the Northern Hemisphere. But, as not all of the rises in insolation throughout time caused deglaciation, to the current ice volumes that we witness today. This leads to a different conclusion, one that suggests that there is a possible climatic threshold, in terms of ice sheets retreating, and eventually disappearing. As Laurentide was the largest mass ice sheet in the Northern Hemisphere, much study has been conducted regarding its disappearance, unloading energy balance models, atmosphere-ocean general circulation models, and surface energy balance models. These studies concluded that the Laurentide ice sheet presented a positive surface mass balance during almost the entirety of its deglaciation, which indicates that the loss of mass throughout its deglaciation was more than likely due to dynamic discharge. It was not until the early Holocene when the surface mass balance switched to become negative. This change to a negative surface mass balance suggested that surface ablation became the driver that resulted in the loss of mass of ice in the Laurentide ice sheet. It is concluded then that the Laurentide ice sheet only began to exhibit behaviours and patterns of deglaciation after radiative forcing and summer temperatures began to rise at the beginning of the Holocene. EmilyDUOregon (talk) 01:22, 13 June 2017 (UTC)

Effects
When the Laurentide ice sheet progressed through the process of deglaciation, it created many new landforms and had various effects of the land. First and foremost, as huge glaciers melt, there is a consequently large volume of meltwater. The volumes of meltwater created many features, including proglacial freshwater lakes, which can be sizable. Not only was there meltwater that formed lakes, there were also storms that blew over the inland freshwater. These storms created waves strong enough to erode the ice shores. Once ice cliffs were exposed, due to rising sea levels and erosion caused by waves, the ice bergs were split and shed (calved) off. Large lakes became prevalent, but so did smaller, shallower, relatively short-lived lakes. This appearance and disappearance of small, shallow lakes influenced much of the plant growth, spread and diversity that we see today. The lakes acted as barriers to plant migration, but when these lakes drained, the plants could migrate and spread very efficiently. As a result, there has been a huge shift in land use since the disappearance of the Laurentide ice sheet, and much of the agriculture we see today was influenced by the rising sea levels due to the melting of such a large ice sheet.

EmilyDUOregon (talk) 03:37, 13 June 2017 (UTC) Bibliography:

Clark, Peter U., Jeremy D. Shakun, Paul A. Baker, Patrick J. Bartlein, Simon Brewer, Ed Brook, Anders E. Carlson, Hai Cheng, Darrell S. Kaufman, Zhengyu Liu, Thomas M. Marchitto, Alan C. Mix, Carrie Morrill, Bette L. Otto-Bliesner, Katharina Pahnke, James M. Russell, Cathy Whitlock, Jess F. Adkins, Jessica L. Blois, Jorie Clark, Steven M. Colman, William B. Curry, Ben P. Flower, Feng He, Thomas C. Johnson, Jean Lynch-Stieglitz, Vera Markgraf, Jerry Mcmanus, Jerry X. Mitrovica, Patricio I. Moreno, and John W. Williams. "Global Climate Evolution during the Last Deglaciation." Proceedings of the National Academy of Sciences of the United States of America 109.19 (2012): E1134. Print.

Cronin, Thomas M. Paleoclimates: understanding climate change past and present. New York: Columbia U Press, 2009. Print.

"Glaciers and Climate Change." Glaciers and Climate Change | National Snow and Data Center. National Snow and Ice Data Center, n.d. Web. 01 June 2017.

"National Snow and Ice Data Center." Glaciers and Climate Change | National Snow and Ice Data Center. N.p., n.d. Web. 12 June 2017.

The Editors of Encyclopædia Britannica. "Laurentide Ice Sheet." Encyclopædia Britannica. Encyclopædia Britannica, Inc., 2013. Web. 01 June 2017.

Ullman, David J., Anders E. Carlson, Faron S. Anslow, Allegra N. Legrande, and Joseph M. Licciardi. "Laurentide Ice-sheet Instability during the LastÂ deglaciation." Nature Geoscience 8.7 (2015): 534-37. Web. 01 June 2017.

Peer Review
Your plan for edits looks like it's off to a good start. Overall, my main comment is to be sure to keep the focus on the topic of the article (deglaciation) and not have so much specific information that is not directly relevant. For example, I like the idea of including some information about the LGM, but would suggest you keep it to a minimum since it's a separate (though definitely related) topic; just be sure to have links to the LGM article! Right now your draft has 2+ paragraphs that are really focused on the LGM. You don't need so much focus on information such as what the forests were like. I think you could justify including some of the information, like how it was cooler/wetter during the LGM, but only if you really explicitly tie it to how deglaciation plays into this. I think your plan to add to the section on the effects of deglaciation is ambitious but good. Maybe just a sentence or two about each of these landforms and then allow the reader to link to the individual pages if they want to know more? I think it would be also good to focus more on what causes deglaciation in general, and not just the last deglaciation. Right now it feels like it's only focused on the LGM-now transition; maybe add something about previous deglaciations? Also, the language could be tightened up a lot from what you have in this draft (make every word count!). But you're making good progress! SkyBlueWater (talk) 05:35, 13 May 2017 (UTC)

All really great comments! Thank you, it's greatly appreciated. I agree about trying not to veer off topic with too much about the LGM, and keeping the effects of deglaciation to just a couple of sentences. I will also take your suggestion to discuss the causes of deglaciation overall, rather than simply the last deglaciation. Thanks again. EmilyDUOregon (talk) 05:15, 16 May 2017 (UTC)