According to a recent study, the Montreal Protocol may be the first international treaty to slow the rate of global warming successfully.
The Montreal Protocol on Substances that Deplete the Ozone Layer is an international agreement from 1987.
Its purpose was to prevent chlorofluorocarbons from destroying the ozone layer. Expectedly, the treaty involved regulating the production and consumption of over 100 human-made chemicals known as ozone-depleting substances.
Now a published article in Environmental Research Letters is saying that the treaty was effective. Thirty-two years after the countries adopted the Protocol, the global temperature is considerably lower.
Thirty years from now, the Earth will be at least 1°C cooler than it would have been without the agreement. By comparison, the Kyoto Agreement — designed to reduce greenhouse gases — will cut global temperatures in the mid-century by only 0.12°C
In a statement about the study, lead author, Rishav Goyal, said:
“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.”
The mitigation effect is even more significant in the Arctic, where warming could reduce by as much as 4°C.
So, how did the team reach this conclusion?
The Effects of Montreal Protocol on Atmospheric Circulation
The researchers wanted to quantify the effect of the Montreal Protocol on atmospheric circulation in Antarctica. So, they modeled the global climate using two scenarios of atmospheric chemistry.
The first and second scenarios considered how the planet would fare with and without the Montreal Protocol enacted, respectively. The team then extended the simulations into the future, using an unmitigated CFC emissions growth of 3 percent per annum.
Findings from the study show the success of the international treaty at mitigating climate change.
For example, it helped us avoid warming between 0.5°C to 1°C in Eurasia, North America, and Africa. What’s more, avoided warming in these areas would jump to 1.5°C to 2°C by mid-century.
The researchers also pointed out that the Protocol reduced the observed accelerated melting in the Greenland and Arctic.
“Montreal sorted out CFC’s, the next big target has to be zeroing out our emissions of carbon dioxide,” said the study co-author, Prof Matthew England.
Unlike CFC emissions, the CO2 concentration level is set to hit an all-time high in 2019. Despite efforts — under the Paris Agreement — to slow emissions, there appears to be no sign of slowing down.
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