Icy landscapes, surrounded by a cold sea: What do we know about the environment in the southern polar region, how will it develop and what role will it play in climate change? An international team of researchers who have evaluated the many studies on Antarctica and the Southern Ocean from the past decade is now providing insights into these questions. They now present the most important key messages on aspects such as regional climate development, biodiversity and the consequences of ocean acidification in an overview article.
Antarctica and the sea surrounding this continent are still some of the most mysterious areas on earth. But the last ten years have seen so many new ones
Insights into this region delivered like never before. “If you look at the period from 1970 to today, around 80 percent of all scientific publications on biology and biochemistry in the Antarctic appeared in the years 2010 to 2020 alone,” says project coordinator Julian Gutt from the Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research (AWI). “For us that was the reason to condense this enormous knowledge in a specialist article”. The AnT-ERA team of 25 experts has evaluated hundreds of specialist articles about the Antarctic from the last decade and worked out key messages on the current and future state of the Antarctic continent and the Southern Ocean.
Changes in the realm of penguin and co
As they report, it is becoming apparent that the Antarctic and its waters are likely to warm up significantly as a result of climate change. Changes in future ice cover will also play an important role in this. While the Antarctic Peninsula, which protrudes into the South Atlantic, has been warming for a long time, the warming and thus the loss of sea ice have also spread to East Antarctica in the past three years. It is not yet clear whether this is a long-term trend or just a short-term change. In any case, this change in environmental conditions is worrying because it can have a significant impact on the future development of the region.
As for the Antarctic landmass, the warming trend means that plant and animal species can be expected to migrate to Antarctica from warmer regions. In the coming decades, the ice-free coastal areas will probably also greener more and more in the southern summer, because mosses and lichens are increasingly spreading there. All in all, this should initially increase the biodiversity in the coastal area. If the warming continues, the species that have adapted to extremely low temperatures could lose out: “We expect such species to retreat to the last remaining very cold areas of the Antarctic,” says Gutt. “That also means that these regions will have to be placed under protection in order to preserve these species.”
Increasingly sour
As far as the Southern Ocean is concerned, which is of great importance in the context of the global climate and the earth’s material cycles, considerable changes are also emerging. The cool sea is not hardly alive – on the contrary: In recent years scientists have demonstrated the wealth of this underwater world, which is partly covered by ice. For example, there are also extensive coral stocks there. For the future development of the complex living environment, the scientists particularly emphasize the importance of the increasing acidification of seawater, which develops in the course of the increased carbon dioxide concentrations in the atmosphere. “There is no question that this mainly causes problems for those living beings that form calcareous shells,” says Gutt. Because the acid impairs the stability and formation of these structures. “It has not yet been possible to say whether species will disappear completely or whether some will adapt their metabolism to the changed conditions,” says the scientist.
A surprising finding of the last ten years of research was that the organisms on the sea floor, such as some sponges or sea squirts, react very quickly to more favorable living conditions and multiply rapidly. But the opposite can also be the case: These organisms are particularly sensitive to certain impairments to their living conditions. With the strong changes that climate change brings with it, these species could therefore also run into problems, according to the scientists.
How much CO2 can the Southern Ocean absorb?
As they also emphasize, the studies to date do not yet provide any conclusive information on the extent to which a loss of sea ice contributes to the fact that the waters around the Antarctic will in future absorb more carbon dioxide from the atmosphere due to increased algae growth. This is important for the balance sheet calculations of the future development of greenhouse gas concentrations. Basically, it has so far been assumed that the algae in the waters around the Antarctic could swallow around 25 percent more CO2 if the area were completely free of sea ice in the future in the southern summer.
However, as the researchers emphasize, their overview shows that such general statements about developments in the deep south of the earth are difficult. “The publications we have analyzed make it clear that the situation is geographically very different,” says Julian Gutt. “But at least we now know which marine areas and measured variables we will have to look more closely at in future in order to find more precise answers,” says the scientist in conclusion.
Source: Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, specialist article: Biological Reviews doi: 10.1111 / brv.12679