/data/photo/2021/10/12/616514b6e4feb.jpg "The Mystery of the Ice Age Trigger Finally Solved, What Causes It? page all")
KOMPAS.com – Researchers at the University of Arizona in a new study have solved two long-standing mysteries about triggers time lapsewhich has puzzled paleo climatologists for a long time.
To understand what drives Earth’s glacial-interglacial cycles, forwards and backwards lapisan is periodically at Northern Hemisphereis a question that is not easy.
Every effort is made by researchers to explain the expansion and contraction of ice masses over thousands of years.
Quoted from PhysTuesday (28/6/2022), this study has been published in the journal Nature Geoscience. In this study, the researchers recommend an explanation for the trigger for past ice ages, which were rapid expansion of the ice sheet that covered much of the Northern Hemisphere during a new ice age.
The findings can also be applied to other glacial periods throughout Earth’s history.
About 100,000 years ago, as mammoths roamed Earth, the climate in the Northern Hemisphere plummeted. In fact, a drastic drop in freezing point at that time could have caused massive, dense ice sheets to form.
Over a period of about 10,000 years, local mountain glaciers grew and formed large ice sheets that covered large parts of Canada, Siberia, and Europe north today.
Also read: How Cold Was Earth in the Last Ice Age? This is the Researcher’s Explanation
While it is widely accepted that periodic ‘shocks’ in Earth’s orbit around the sun trigger a cooling in the Northern Hemisphere summer that causes widespread glaciation, scientists have struggled to explain what Earth’s ice age triggerwhere the vast ice sheet that covers most of the Scandinavia and northern Europe, where temperatures are much milder.
In contrast to the cold Canadian Arctic Islands where ice forms easily, most of Scandinavia should remain ice-free due to the Current North Atlanticwhich brings warm water to the northwestern coast of Europe.
Although the two regions lie along the same latitude, researchers say Scandinavian summer temperatures are well above freezing, while temperatures in much of the Canadian Arctic remain below freezing during the summer.
According to the study’s lead author, Marcus Lofverstrom, because of these differences, climate models have struggled to explain the extensive glaciers that developed in northern Europe and marked the beginning of the last ice age.
“The problem is we don’t know where the ice sheet (in Scandinavia) came from and what caused it to expand in such a short time,” said Lofverstrom, assistant professor of geosciences and head of the UArizona Earth System Dynamics Lab.
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Lofverstrom helped develop a very complex model of the Earth system to answer this question. The model is known as the Community Earth System Model, which allows his team to realistically recreate conditions that existed at the start of the most recent glacial period.
Through this updated configuration of the model, the researchers identified sea gates in the Canadian Arctic Islands as the key driver controlling North Atlantic climate and ultimately determining whether or not ice sheets could grow in Scandinavia.
Simulations to reveal the triggers of Earth’s past ice ages, show that as long as sea gates in the Canadian Arctic Islands remain open, the configuration of Earth’s orbit cools the Northern Hemisphere enough to allow ice sheets to build up in Northern Canada and Siberia, but not Scandinavia.
“Using climate model simulations and ocean sediment analysis, we demonstrated that ice formation in northern Canada could block ocean gates and divert water transport from the Arctic to the North Atlantic,” Lofverstrom said.
In turn, says Lofverstrom, this causes a weakening of ocean circulation, resulting in cold conditions off the Scandinavian coast enough to start growing ice in the region.
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“These findings are supported by marine sedimentary records from the North Atlantic, which show evidence of glaciers in northern Canada several thousand years before the European side,” said Diane Thompson, assistant professor in the UArizona Department of Geosciences.
Thompson added that the sediment record also shows strong evidence of weakening deep ocean circulation before glaciers formed in Scandinavia. This condition is similar to the results of the modeling conducted by the researchers.
Pushing climate models beyond traditional applications for predicting future climates could provide an opportunity to identify previously unknown interactions in the Earth system, such as the complex and sometimes conflicting interactions between ice sheets and climate, Lofverstrom said.
“It is possible that the mechanisms we identified here apply to every glacial period, not just the most recent,” he explained.
“This (climate modeling to study the triggers of Earth’s ice ages) could even help explain shorter cold periods such as the Cold Reversal of the Younger Dryas (12,900 to 11,700 years ago) that marked general warming at the end of the last ice age,” Lofvestrom added.
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