Saving the ozone layer drastically reduced climate change effects

With so many dire reports coming out about the state of the climate, it’s easy to feel hopeless. But humanity has shown in the past that we can come together to solve seemingly insurmountable environmental problems. The Montreal Protocol in the 1980s has allowed the ozone layer to recover, and now scientists have found that it had another benefit – it’s already slowed climate change by as much as 25 percent.

High in the atmosphere, the ozone layer helps keep Earth habitable by reflecting away the worst of the Sun’s damaging radiation. But in the mid-1980s, scientists discovered a massive hole in this layer over Antarctica. Within a few years, almost 200 United Nations countries signed the Montreal Protocol banning the use of chlorofluorocarbons (CFCs), which were pinned as the culprit.

Now, with the ozone layer hole shrinking rapidly 30 years on, this is often heralded as a success story for global environmental action. And according to a new study from the University of New South Wales (UNSW), the outcome may be even better than we thought.

The researchers modeled the global climate using two different scenarios – one with the Montreal Protocol being enacted, and one without. These covered the period from when it was enacted in the 80s to now, and projected into the future using a conservative estimate of 3 percent growth per year.

The team found that many measures of climate change were significantly better off under the Montreal Protocol than they would have been under a business-as-usual scenario. The average global temperature is set to be at least 1° C (1.8° F) cooler by mid-century than it would have been otherwise, and that figure rises to between 3° and 4° C (5.4° and 7.2° F) in the Arctic.

“By mass CFCs are thousands of times more potent a greenhouse gas compared to CO2, so the Montreal Protocol not only saved the ozone layer but it also mitigated a substantial fraction of global warming,” says Rishav Goyal, lead author of the study. “Remarkably, the Protocol has had a far greater impact on global warming than the Kyoto Agreement, which was specifically designed to reduce greenhouse gases. Action taken as part of the Kyoto Agreement will only reduce temperatures by 0.12° C (0.22° F) by the middle of the century – compared to a full 1° C of mitigation from the Montreal Protocol.”

It’s not just plain surface temperatures either – the Montreal Protocol has lessened the negative run-on effects of climate change too. Arctic summer sea ice extent is estimated to be about 25 percent higher today than it would be otherwise. The melting of Greenland’s ice sheet and sea level rise are also happening slower thanks to the Protocol.

It’s easy to look at climate change as too big a problem for us to solve, but this study gives us renewed hope. It will require unprecedented changes to all aspects of society – but that is achievable if we act sooner rather than later.

“The success of the Montreal Protocol demonstrates superbly that international treaties to limit greenhouse gas emissions really do work,” says Matthew England, co-author of the study. “They can impact our climate in very favorable ways, and they can help us avoid dangerous levels of climate change. Montreal sorted out CFCs, the next big target has to be zeroing out our emissions of carbon dioxide.”