Nearly 40% of the world's glaciers are already doomed, scientists say

CNN

2 days ago

The world's glaciers are in dire health with almost 40% of their total mass already doomed, even if global temperatures stopped rising immediately, a new study has found.
Researchers estimate glaciers will eventually lose 39% of their mass relative to 2020, a trend that is already irreversible no matter what comes next and will likely contribute a 113-millimeter increase to global sea level rise.
The loss rises to 76% if the world continues to pursue its current climate policies, which will likely fail to keep global warming under 1.5 degrees Celsius, according to a paper published in the journal Science.
The latter scenario could prove disastrous for countries that depend on glacial meltwater for irrigation, power and drinking water; a world in which 39% of the glacier mass is lost compared to 76% is the 'difference between being able to adapt to the loss of the glacier and not,' James Kirkham, a glaciologist at the International Cryosphere Climate Initiative told CNN.
Even though the study offers a bleak prognosis for the world's glaciers, its authors are trying 'to give a message of hope,' said Lilian Schuster, a researcher at the University of Innsbruck in Austria, who co-led the study.
'With the study, we want to show that with every tenth of a degree less of global warming, we can preserve glacier ice,' she told CNN.
Nearly 200 nations pledged to work together in the 2015 Paris Agreement to limit global warming. Nations committed to keep global warming below 2 degrees Celsius above pre-industrial levels and, if possible, below 1.5 degrees. Each country is responsible for developing its own plans for achieving those goals.
But temperatures keep rising — the world is currently on track for up to 2.9 degrees of warming by 2100. And every additional increase of 0.1 degrees between 1.5 and 3 degrees of warming results in an additional 2% of the global glacier mass being lost, the study predicts.
'We're not activists, this is science talking,' said Harry Zekollari, a researcher at Vrije Universiteit Brussel in Belgium and ETH Zürich in Switzerland, who co-led the study.
'Sometimes, the remarks we get is like 'you're alarmist and making people scared.' I say, 'I'm trying to give out what our computer numbers give us.''
This 'landmark' study is 'one of the most important pieces of glacier projection work that's been done this decade,' said Kirkham, who wasn't part of the research team but presented the paper at a United Nations conference on Saturday.
Until this paper, previous projection studies ended their predictions at 2100 — the date often used in policy circles to measure the potential effect of the climate crisis, Kirkham said. But glaciers can take years, even centuries, to stabilize after the climate has changed, meaning that the true effect of rising temperatures can be masked for years, too.
To investigate this phenomenon, this study used eight pre-existing glacier models and ran simulations stretching over centuries, predicting how each glacier will evolve in that timeframe.
Using so many models produced a wide range of results. For example, the finding that glaciers will eventually lose 39% of their mass if current temperatures persist was the median result in a data set ranging from 15% to 55%.
But although the range of results is 'quite large,' they're 'all showing the same trend,' said Guðfinna Aðalgeirsdóttir, a professor at the University of Iceland, who wasn't involved in the study.
'The message is very clear,' she told CNN. 'All the models are showing the same thing, that with increased warming, the more mass of glaciers we lose.'
For Zekollari, the uncertainties in the results show 'there's still a lot to be done when it comes to comparing the different models.'
These effects vary by region too, depending on how exposed each glacier is to climate change, the study found.
Glaciers in Western Canada and the United States, northeast Canada, Scandinavia and the Russian Arctic are among those particularly at risk.