Twenty year pause in loss of Arctic sea ice observed in new study

There has been a massive slowdown in the loss of Arctic sea ice over the last 20 years, new research shows.

While the slowdown sounds surprising, researchers said pauses like these are consistent with human-caused global warming trends.

In a study published this month in the journal Geophysical* Research Letters, researchers from the University of Exeter analysed Arctic sea ice cover using two different datasets* of satellite measurements from 1979 to the present.

“Over the past two decades, Arctic sea ice loss has slowed considerably, with no statistically* significant decline in September sea ice area since 2005,” they wrote.

Focusing on September, when sea ice cover is most reduced, they found sea ice declined by 0.35 and 0.29 million square kilometres per decade between 2005 and 2024.

Compared with the longer-term rate of decline since 1979 of 0.78 to 0.79 million square kilometres per decade, that marked a 55 per cent to 63 per cent slowdown.

The 20-year period was the slowest rate of sea ice loss since records began, and four to five times slower than the peak 20-year period of 1993 to 2012.

But the researchers said climate models* show pauses in sea ice loss across multiple decades could happen even as greenhouse gas emissions continue to rise. These pauses were likely because of “natural climate variations*.”

Climate models suggest the chances of such a slowdown were about 20 per cent.

The models suggest the pause could continue for another five to 10 years, however the current slowdown made it more likely that faster-than-average sea ice loss would occur over the coming years, the study stated.

“Summer sea ice conditions in the Arctic are at least 33 per cent lower than they were at the beginning of the satellite record nearly 50 years ago,” Dr Mark England, who led the study while at the University of Exeter and is now at UC Irvine, said in a statement.

“This is only a ‘temporary reprieve*’ and before long the rate of sea ice decline will catch up with the longer term rate of sea ice loss.

“It’s like the analogy* of a ball bouncing down a hill where the hill is climate change, given by Professor Ed Hawkins.

“The ball continues going down the hill but as it meets obstacles in its path, the ball can temporarily fly upwards or sideways and not seem to be travelling down at all — that trajectory* is not always smooth but we know that at some point the ball will careen* towards the bottom of the hill.”

When the current slowdown ends, climate modelling suggests the rate of sea ice loss could speed up to 0.6 million square kilometres per decade faster than the longer-term trend.

The researchers estimate that the current pause has a nearly one in two chance of lasting another five years, and a 25 per cent chance of lasting another 10 years.

While most of the evidence from climate models suggest natural climate variations had played a large part in slowing the “human-driven loss of sea ice”, the modelling couldn’t say with certainty whether the actions of humans had also helped to slow down the loss of ice.

According to the researchers, “we should expect periods like this to occur somewhat frequently.”

It comes as a separate study from researchers at two Australian universities, UNSW Sydney and the ANU, published in the journal Nature, warns of “catastrophic consequences” for Antarctica unless urgent actions are taken to cut global carbon emissions.

“Rapid change has already been detected across Antarctica’s ice, oceans and ecosystems — and this is set to worsen with every fraction of a degree of global warming,” said Australian Antarctic Division (AAD) chief scientist and lead author Dr Nerilie Abram.

Dr Abram said the sudden loss of sea ice in the region had a range of knock-on effects.

“This includes making the floating ice shelves around Antarctica more susceptible* to wave-driven* collapse,” she said.

She said the West Antarctic Ice Sheet* (WAIS) was at serious risk of collapse as global carbon dioxide levels continue to rise. This loss would raise sea levels by more than three metres, threatening coastal cities and communities worldwide.

“Such a collapse would result in catastrophic consequences for generations to come,” she said.

POLL

GLOSSARY

• Geophysical: relating to the physics of the earth
• datasets: related sets of information made up of different elements that can be manipulated as a unit by a computer
• statistically: based on the information collected
• climate models: computer simulations of Earth’s climate system that can be used to predict the future climate
• variations: changes or differences
• reprieve: a pause or lessening of something
• analogy: a literary device that draws a comparison between two different things to explain a point
• trajectory: path of an object moving under the action of given forces
• careen: moving rapidly in an uncontrolled way
• susceptible: likely to be influenced or harmed by something
• wave-driven: collapse caused by a wave
• West Antarctic Ice Sheet (WAIS): a segment of the continental ice sheet that covers West Antarctica, which is strongly affected by climate change and has been losing ice since at least the 1990s

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QUICK QUIZ
1. What has slowed down over the last 20 years?
2. What has likely caused this slowdown?
3. How much longer could the slowdown last?
4. What might happen after the slowdown?
5. What might the consequences be if the West Antarctic Ice Sheet collapses due to global warming?

LISTEN TO THIS STORY

CLASSROOM ACTIVITIES
1. Spin it
The findings of the study in this story could easily be misrepresented if one were to “cherry pick” only parts of the data. Cherry picking means only using data that supports a particular point of view and omitting other relevant facts. It is important to be aware of this practise so that you can better identify biased information.

To see how easy it is to “spin” information, write a short, summarised version (100 words) of this news article that cherry picks data to present the findings as positive news for the environment, even though it is not positive.

Time: allow 30+ minutes to complete this activity
Curriculum Links: English; Critical and Creative Thinking

2. Extension
Now that you are aware of “cherry picking,” how might this impact the way you think about articles you read where data is presented? Write a paragraph to explain.

Time: allow 10 minutes to complete this activity
Curriculum Links: English; Critical and Creative Thinking

VCOP ACTIVITY
BAB it!
Show you have read and understood the article by writing three sentences using the connectives “because’’, “and”, and “but” (BAB). Your sentences can share different facts or opinions, or the same ones but written about in different ways.