In terms of ancient climate, there are two mysteries that have puzzled many paleoclimatologists. This is where did the ice sheets of the last ice age come from? Why are they growing so fast?
Now, a new study may have solved these mysteries.
The last ice age began 116,000 years ago, and the northern hemisphere was covered with huge ice sheets. However, what surprised scientists was that it took only 10,000 years for this ice sheet to complete the complete process from appearance to disappearance.
Scientists are trying to explain the vast ice cap areas of northern Europe and Scandinavia, which are largely ice-free due to heat brought by the North Atlantic Ocean Current.
"The problem is, we don't know where these ice sheets came from and what prompted them to expand in such a short period of time," said lead author Markus Lofstrom.
The authors of this study developed a complex model of terrestrial systems called the Terrestrial System Community Model. The model can reproduce the first climatic conditions of the recent ice age in high spatial detail
Researchers have found that the harbors of the Canadian Arctic Archipelago are critical for controlling the climate of the North Atlantic.
The model suggests that as long as the Canadian Arctic Archipelago remains open, the Northern Hemisphere will be cooled sufficiently by the structure of Earth's orbit to allow ice sheets to accumulate in northern Canada and Siberia..
The team also explored whether ocean ice sheets could block waterways on Canada's Arctic Ocean islands. Normally, fresh water from the Arctic and North Pacific passes through the Canadian Arctic Archipelago - in this case, it actually diverts to the east of Greenland. This deviation causes the deep circulation in the North Atlantic to weaken and strengthen, resulting in cooler Scandinavian climate and expanded sea ice.
Lofstrom suggested that through climate model simulations and analysis of ocean sediments, we feel that ice in northern Canada will block ocean channels and transport water from the Arctic to the North Atlantic. This in turn causes ocean circulation to weaken. Cold conditions near the Scandinavian coast are enough for ice to start forming in the area.
These results are supported by the North Atlantic sediment record, which shows that glaciers in northern Canada are thousands of years older than those in Europe, and by strong evidence of weakened deep-water circulation that preceded the formation of Scandinavian glaciers. Similar to the modeling results.
Taken together, these experiments may show that the formation of northern Canadian sea ice is necessary for the formation of Scandinavian glaciers.
Lofström proudly says: "The mechanism we studied and identified can be applied to every ice age, not just the last one, which also helps explain why there are shorter cold periods, e.g. Cold reversal brought about by the young Andromedids (12,900-11,700 years ago), which interrupted the overall warming at the end of the last glacial period
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