Greenland and Antarctica Are Losing Ice Faster Than Ever — 11.3 Trillion Tonnes Gone in Decades

An international team of polar scientists has analysed decades of satellite data on the state of the Greenland and Antarctic ice sheets and reached a troubling conclusion: over the period of observation, these regions have lost roughly 11.3 trillion tonnes of ice. That much water has raised the average global sea level by around 3.2 centimetres.

At first glance, a few centimetres might not sound like much. But according to study co-author Inès Otosaka, a glaciologist at Northumbria University in the UK, every centimetre comes at a cost. "Every centimetre of sea level rise matters. Each additional centimetre means that two to three million more people could be exposed to annual coastal flooding," she told the Associated Press.

It's worth noting that these figures reflect only the contribution from Greenland and Antarctica. Global sea level rise is also driven by melting mountain glaciers and the thermal expansion of warming seawater.

Ice Is Flowing Into the Ocean, Not Just Melting

One of the study's key findings concerns the mechanism behind the losses. It turns out that around 84% of the ice loss in Greenland and Antarctica comes from accelerated ice flow directly from land into the ocean, while only 16% is due to surface processes, primarily melting.

According to Otosaka, this is the first time scientists have been able to pin down this ratio precisely. The results show that ocean-related processes contribute far more to ice loss than earlier estimates suggested.

Accelerating Decade After Decade

In the 1970s and 1980s, and partly into the 1990s, the mass balance of both ice sheets remained relatively stable. After that, losses began to climb noticeably, and in recent decades the pace of ice loss has sharply accelerated.

"The satellite record shows a clear trend: the ice sheets are losing more and more mass, and that loss is growing decade by decade," Otosaka said.

The link to climate change is clear, she noted: rising air temperatures speed up surface melt, while a warming ocean drives faster ice flow from land into the sea. At the same time, ice sheets respond to warming with a considerable time lag — as co-author Andrew Shepherd pointed out, some processes set in motion decades ago may continue for decades more, even if further warming were halted today.

Source: novinky.cz