A new study sheds interesting light on the early de-icing of Antarctica thousands of years ago: It began at a time when CO2 in the atmosphere was at extremely low levels. It also denies a direct relationship between CO2 levels and surface temperatures on Earth. Rather, it once again confirms the impact of solar radiation on the global climate.
About 21,000 to 19,500 years ago, atmospheric CO2 was at a very low level of about 180 ppm and has been rising since then. But according to a new study, by that time, sea ice had already completed about half of its total decline by retreating from its maximum extent. It is called:
“Independent evidence suggests that early sea ice and surface ocean changes in the Southern Ocean began about 19,500 years ago (our reconstruction indicated summer sea ice retreat about 21,000 years ago) and therefore (at least Low) approximately 2,000 years before major glacial changes in global ocean circulation, climate and atmospheric CO2.”
This is due to increased solar radiation at 65° south. The scientists explain further in the study: “This initial increase in local integrated summer solar radiation at 65°S, which is independent of longitude, may therefore provide enough energy to initiate nearly year-round melting of sea ice cover. ” Late glaciation.”
Thus the millennium-scale lag suggests not only that CO2 was not a determining factor in Antarctic sea ice decline, but also that sea ice decline may have been the factor that sequentially increased Antarctic temperatures and CO2. Has increased. “Our results support the important role of changes in Antarctic sea ice cover in contributing to, and potentially triggering, Southern Ocean overturning during the last glacial-interglacial transition, atmospheric CO2 and Antarctic climate.”Scientists say.
This means: Within about 5,800 years (between about 17,500 and 11,700 years ago) temperatures in the Antarctic region had increased by about eight degrees Celsius. But this began two millennia ago with CO2 levels rising by about 80 ppm. Another way of saying this is that warming and de-icing caused life to become more active, which also increased CO2 levels in the atmosphere over time. Carbon dioxide is also a product of biological (especially animal) life and food for plants (photosynthesis).