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Sea-level rise: West Antarctic ice shelf melt 'unavoidable'

来源:BBC 作者: 时间:2023-10-24 Tag: 点击:

Increased melting of West Antarctica's ice shelves is "unavoidable" in the coming decades, a new study has warned.

These floating tongues of ice extend from the main ice sheet into the ocean, and play a key role in holding back the glaciers behind.

But as ice shelves melt, it can mean that the ice behind speeds up, releasing more into the oceans.

The study's findings suggest that future sea-level rise may be greater than previously assumed.

"Our findings seem to increase the likelihood that [current] estimates [of sea-level rise] will be exceeded," Dr Kaitlin Naughten of the British Antarctic Survey (BAS), the report's lead author, told the BBC.

In 2021, the UN's climate body, the Intergovernmental Panel on Climate Change (IPCC), released its latest estimates of future sea-level rise.

 

It projected global average sea-level rise of between 0.28m and 1.01m by 2100 - one key reason being the melting of glaciers and ice sheets.

Sea-level rises of around a metre may not sound much, but even these increases would put hundreds of millions of people worldwide at risk of coastal flooding.

However, the IPCC also noted that higher rises were possible due to "ice-sheet-related processes that are characterised by deep uncertainty" that were not directly included in its estimates.

One of these key uncertainties is how the ice sheet interacts with the oceans.

This latest study, published in the journal Nature Climate Change, is the first to directly simulate how ocean warming will affect Antarctic ice shelves in response to different levels of greenhouse gas emissions. These are the gases produced when fossil fuels are burned - the main contributor to human-induced climate change.

Amundsen Sea, off the coast of West Antarctica, will warm roughly three times faster than the historical rate through the rest of this century, the study finds. This will lead to much more rapid melting of ice shelves.

 

Concerningly, this will still happen even if humanity takes strong steps to slow warming, the study suggests. But this is not a reason to avoid moving away from fossil fuels, Dr Naughten stresses.

"What we do now will help to slow the rate of sea-level rise in the long term," she explains.

The authors caution that further work is needed to increase confidence in its conclusions, but the findings are significant because of how ice shelf melting affects the rest of West Antarctica.

The importance of ice shelves

The Antarctic ice sheet contains enough ice to raise global sea-levels by about 58m (190ft) if it melted entirely.

Most is held in East Antarctica, which has been relatively stable in recent years and is not expected to collapse in the near future.

But a sizeable portion - enough to raise sea-levels by around 5m (16ft) - is held in West Antarctica, which is considered less stable and has been losing mass in recent decades.

 

 


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