Wikipedia:Reference desk/Archives/Science/2023 November 10

= November 10 =

Sea rise
All are saying that melting icebergs in North Pole will rise the sea level. But we all know that Ice has more volume than water. Then melting ice should reduce sea level as most of iceberg is underwater. Mrollsua (talk) 06:37, 10 November 2023 (UTC)


 * Floating ice displaces as much water by weight as the ice itself weighs, see Archimedes' principle and Buoyancy. If the ice melts then it will nearly exactly filly the "hole" left by its melting.  It's not quite exact due to salinity issues; polar ice is basically fresh water.  However the same is not true of glaciers and ice sheets over land.  Melting of the ice over the Antarctic continent would result in fresh water run-off from land to ocean, and that would raise sea levels significantly.  Martin of Sheffield (talk)


 * If you look at the effect of melting ice only, the icebergs in the north are not the biggest issue, the ice on top of land in Antartica is a bigger issue.
 * The effect of warmer oceans is lower water density, which does contribute to higher sea levels.
 * However, the secondary effects of melting ice are also relevant. Ice is white, which reflects light more than water (which isn't white). This means that having less ice cover will increase the temperature due to solar irradiation (see Albedo).
 * Another important effect is that the meltwater has an effect on the ocean currents (mentioned in Climate_change). These have a large role in weather patterns and climate, which potentially causes sea levels rising too. Rmvandijk (talk) 08:20, 10 November 2023 (UTC)
 * For an exposition of how the melting of West Antarctica's ice shelves contributes to a sea-level rise (and a dire prediction), see this BBC article. If the sea level rises by almost 6 metres, instead of the currently accepted worst-case scenario rise of less than 2 meters by the end of the century, the Netherlands may need to build 10-metre high dikes around Amsterdam, Rotterdam and The Hague and let much of the rest of Holland be reclaimed by the sea. --Lambiam 12:52, 10 November 2023 (UTC)


 * And if the sea level rises by 600m by the end of the century we all die. So what? There is no sign of signficant acceleration form 3mm per year, which leads to the 2m figure. The BBC is not reliable on climate. Try the grownups at https://www.climate.gov/news-features/understanding-climate/climate-change-global-sea-level Greglocock (talk) 20:31, 10 November 2023 (UTC)
 * The BBC was merely reporting the findings of a study published in Nature Climate Change, which I think we consider a reliable source. The BBC article appears to present a fair summary of the findings of this study, which is cited in the last paragraph of . The 2.2 meters figure given by your grownups is not cited to a specific source, but appears to be due to the 2022 "Interagency Sea Level Rise Technical Report", which is based on the optimistic assumption that the 2 °C limit of the Paris Agreement will not be exceeded and hedges its prediction by stating, "While these low-confidence ice-sheet processes are unlikely to make significant contributions with 2°C of warming, how much warming might be required to trigger them is currently unknown." In 2013, the web page cited the IPCC's "18 to 59 cm (7 to 23 inches) by 2100". You might consider the possibility that new research leads to a revision of previous estimates. --Lambiam 08:51, 11 November 2023 (UTC)
 * Was there a question here? Seems to be a statement, and not a question. --OuroborosCobra (talk) 14:52, 10 November 2023 (UTC)
 * The implied question appears to be, "Is my reasoning correct?". The answer is no. Additionally, the opening sentence of the OP is factually incorrect. --Lambiam 15:39, 10 November 2023 (UTC)


 * OP may have in mind the Greenland ice sheet rather than icebergs. From our article: "If the entire 2,850,000 cubic kilometres (684,000 cu mi) of ice were to melt, it would lead to a global sea level rise of 7.2 m (24 ft), although this is expected to take millennia to fully play out." --Amble (talk) 18:17, 10 November 2023 (UTC)


 * As a different but connected issue, all those floating Arctic marine ice sheets and icebergs are made of fresh water (because freezing salt water forces out the salt). If/when they melt, the Arctic ocean salinity will change: this may have Consequences. {The poster formerly known as 87.81.230.195} 94.2.5.208 (talk) 18:55, 10 November 2023 (UTC)