Large pieces of ice splinter off Greenland’s Eki glacier
Eloy Omera/Getty Images
The first ice-free Arctic summer is predicted to occur around the middle of this century. Without the Montreal Protocol, an international treaty banning ozone-depleting gases, that milestone might have been even earlier.
In 1987, most of the world’s nations met in Montreal to agree on a plan to phase out the use of ozone-depleting chlorofluorocarbons (CFCs) and other aerosols. These ozone-depleting substances are also greenhouse gases, thousands of times more powerful than carbon dioxide.
Although the main concern at the time was the protection of the ozone layer, the resulting treaty also brought unexpected benefits to the climate. It has helped reduce warming, reduce the intensity of tropical cyclones, and store more carbon in plants.
According to an analysis by Mark Englund of the University of Exeter, UK, and others, the effects of the treaty slowed, but did not stop, the loss of Arctic sea ice due to climate change. He and his team use climate and ice models to predict the extent of Arctic sea ice with or without the Montreal Protocol, accounting for reduced CFC emissions and consequent recovery of the ozone layer. Did. They also considered the impact of gases used to replace CFCs.
The analysis showed that without the Montreal Protocol, the first ice-free Arctic summer would have occurred sometime between 2030 and 2038, depending on the model. The first ice-free summer is expected between 2037 and 2054, the researchers found, assuming moderate to high future greenhouse gas emissions once the treaty takes effect. .
England says the first ice-free summer in the Arctic – defined as the first September when ice cover is less than 1 million square kilometers – will affect not only shipping routes but also ice-dependent ecosystems and communities. . “This is an alarming indicator of how much we have changed the climate system,” he says.
The UK said its best projections suggest ice-free Arctic summers are “approaching the inevitable”, even if emissions are significantly cut. But how often they occur depends on the amount of greenhouse gases released, he says. Controlling powerful but short-lived methane emissions could have a particularly large impact.
The work on the Montreal Protocol itself is also largely unfinished. In April, researchers reported that atmospheric concentrations of CFCs had risen sharply since 2010, despite a ban on their production. And many of the aerosols used as CFC replacements are powerful greenhouse gases in their own right and are now set to be phased out after the original treaty’s renewal.
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