Good News: A 1987 Treaty Has Successfully Preserved Arctic Ice, Scientists Say

Right now, in some alternate universe, we might be mourning the loss of summer ice over the Arctic Ocean, a grim climate milestone that is expected by midcentury. We’re not, though, and it’s thanks to the Montreal Protocol, a major treaty ratified in 1989, reports a new study.

More than 30 years ago, nations from all across the globe joined forces to ratify the protocol, which bans chemical pollutants that are harmful to Earth’s ozone layer, a region of our atmosphere that is critical to our survival. Decades later, the Montreal Protocol has delivered on its main aim of healing the “ozone hole” over Antarctica, while also producing a host of other environmental benefits, earning it a reputation as one of the greatest environmental success stories in history.

Now, a pair of scientists have concluded that the Montreal Protocol also singlehandedly delayed the onset of the first ice-free summer in the Arctic by about 15 years by slowing the rapid loss of sea ice as a result of human-driven climate change. At some point in the coming decades, a September will arrive in which there is no sea ice cover over the Arctic Ocean, marking the beginning of the first iceless Arctic summers in millions of years. But it will not be this September, or any September for many years, thanks to the Montreal Protocol.

The new findings “reveal an important, largely unforeseen, benefit from the implementation of the Montreal Protocol” that provide “new evidence that the Montreal Protocol, in addition to saving the ozone layer, has proven to be a very important mitigation treaty for Arctic climate,” according to a study published on Monday in Proceedings of the National Academy of Sciences.

“I don't think people were thinking about the Arctic really at all when they were drafting this protocol,” said Mark England, a senior research fellow at the University of Exeter who co-authored the study, in a call with Motherboard. “They were firmly in the other hemisphere and pole, in the Antarctic, so there are good unintended consequences of some of these climate actions.” 

Ozone-depleting substances (ODS) were once common in products such as aerosol sprays or refrigerants, but they were prohibited by the Montreal Protocol due to their erosive effect on the ozone layer, particularly around the South Pole. Because ODS are also extremely potent greenhouse gasses, the treaty has also had many serendipitous climate and ecological benefits.

 England and study co-author Lorenzo Polvani, a climate scientist at Columbia University, previously found that ODS had played a huge role in Arctic warming during the 20th century.  

To follow up on that research, the pair ran a range of climate models to hone in on the specific effect that the treaty may have had on the timeline of the first icefree summer, a turning point that will have significant societal and ecological ramifications for the region. 

The results revealed that the Montreal Protocol has helped to preserve sea ice in the Arctic, just as it helped preserve the ozone over the Antarctic. But though the ozone layer is expected to continue healing, there is unfortunately no way to avoid the loss of Arctic summer sea ice. 

“What’s useful was putting a number on it for the wider public to quantify from these comprehensive climate models exactly how much we've managed to delay it,” England said. “It is positive news that we've delayed it, but we are just delayed. That's part of the negative news. This is not the only solution we can rely on.”

“Ozone-depleting substances are important but they're not [carbon dioxide], which is the main contributor to climate change,” he noted. “All the action we can do on those is helping to delay the worst impacts of climate change, but it takes a large reduction in emissions of CO2, for example, to actually stop the planet from warming.”

To that end, the Montreal Protocol can serve as a positive roadmap for current and future efforts to prevent some of the worst disasters that are expected in a warming world, including extreme weather and sea level rise. The barrage of bad news about the climate crisis can make it seem as if we’re in one of the darkest timelines, but this celebrated treaty is a light from the past that proves dramatic change is possible—though time is of the essence.

“We took very early action on the Montreal Protocol, considering when we first understood about the potential ozone hole, and that was really key for the benefits that are happening today,” England said. 

“I think it’s also important to take stock of what we’ve managed to achieve, because if we keep looking forward, we don't understand how much success we've had in the past,” he concluded.