[ad_1]
Changes in the Antarctic ice sheet at the bottom of the southern hemisphere were triggered by changes in sea level in the northern hemisphere over the past 40,000 years, a new study has found.
Researchers at McGill University have found that ice caps at opposite ends of the Earth can influence each other by changing sea levels in surrounding waters.
Scientists have struggled to explain how the ice caps changed during the last ice age – the last ice age – from 115,000 years ago to 11,700 years ago.
New models have shown that as the climate in the northern hemisphere cools and more and more water turns to ice, the sea level in Antarctica is falling, causing its ice cap to grow.
Likewise, as temperatures rose again, the northern hemisphere’s ice caps retreated, causing levels to rise around Antarctica and its ice cap.
Polar ice caps evolve on different time scales and are constantly changing, with ice growing and retreating depending on the climate and surrounding water levels.
Lead author Professor Natalya Gomez of McGill University said ice caps can influence each other for thousands of miles due to the water flowing between them.
“It’s like they’re talking to each other through changes in sea level,” she said.
The team reviewed existing models, geological records, core samples from the Antarctic Ocean floor, and exposure records from shore lands.
Professor Gomez said the polar ice caps are not just large static ice mounds.
“They evolve at different timescales and are constantly changing, with the ice growing and shrinking depending on the climate and surrounding water levels.
“ They gain ice when snow collects on them, then spread under their own weight and flow into the surrounding ocean where their edges break into icebergs, ” Gomez explained.
Using this information, they were able to simulate simultaneous changes in sea level and ice dynamics in both hemispheres over the past 40,000 years.
This time frame provides a broader picture of how climatic factors affect ice caps, as it captures the retreat from the peak of the last ice age up to 26,000 years ago.
To study the mechanisms involved in driving changes in the Antarctic ice sheet, researchers looked at a wide range of geological records, from sediment cores on the ocean floor near Antarctica to land exposure records. and past shores.
The Antarctic ice caps lost a significant amount of ice during this time, with occasional periods of accelerated retreat, according to the records.
The only possible explanation, scientists say, was the changes in sea level caused by the growth or retreat of ice caps in the northern hemisphere.
Co-author Michael Weber from the University of Bonn in Germany said: “ We have found a highly variable signal of ice mass loss over the past 20,000 years, left behind by icebergs breaking up Antarctica and melting into the surrounding oceans.
“This evidence could hardly be reconciled with existing models until we explained how the ice caps in both hemispheres interact with each other.
The Antarctic ice sheet spans nearly 5.4 million square miles, roughly the same size as the United States and Mexico combined.
Researchers were able, for the first time, to simultaneously simulate changes in sea level and ice dynamics in both hemispheres over the past 40,000 years.
Professor Gomez added: “ The scale and complexity of ice caps and oceans, as well as the secrets of Earth’s past climate that are locked away in the geological record are fascinating and inspiring.
“Our results show just how interconnected the Earth system is, with changes in one part of the planet leading to changes in another.
“ In the modern age, we haven’t seen the kind of big ice cap retreat that we might see in our future warming world.
“Looking at records and models of changes in Earth’s history can tell us.”
The results were published in the journal Nature.
[ad_2]
Source link