Montreal Protocol Is Delaying First Ice-Free Arctic Summer
This story was originally published by Columbia Engineering.
When scientists discovered a hole over Antarctica in 1985, countries across the globe got together and wrote a treaty designed to guard the ozone layer, which shields the Earth—and us—from harmful levels of ultraviolet radiation. The resulting Montreal Protocol, the one United Nations treaty ratified by every country on the earth, was signed in 1987 and entered into effect in 1989, when little was known about its impact on the worldwide climate. Its purpose was to scale back atmospheric concentrations of ozone-depleting substances, corresponding to materials commonly utilized in products corresponding to fridges, air conditioners, fire extinguishers, and aerosols. For greater than 50 years, it has been a vital mitigation treaty, affecting many elements of the worldwide climate.
The Advantages of the Mitigation Treaty
A latest study led by climate researchers at Columbia Engineering and the University of Exeter demonstrates that the treaty’s impact reaches all the way in which into the Arctic: its implementation is delaying the occurrence of the primary ice-free Arctic by as much as 15 years, depending on the main points of future emissions. The study was published today by PNAS.
“The primary ice-free Arctic summer—with the Arctic Ocean practically freed from sea ice—might be a serious milestone within the means of climate change, and our findings were a surprise to us,” said the study’s co-author Lorenzo Polvani, Maurice Ewing and J. Lamar Worzel Professor of Geophysics within the department of applied physics and applied mathematics and professor of earth and environmental sciences. “Our results show that the climate advantages from the Montreal Protocol are usually not in some faraway future: the Protocol is delaying the melting of Arctic sea ice at this very moment. That’s what a successful climate treaty does: it yields measurable results inside a number of many years of its implementation.”
The Impact of Ozone-Depleting Substances
Polvani noted that the rapid melting of Arctic sea ice is the biggest and clearest signal of anthropogenic climate change. Current projections indicate that the primary ice-free Arctic summer will likely occur by 2050, owing largely to increasing carbon dioxide concentrations within the atmosphere. Nevertheless, other powerful greenhouse gases have also contributed to Arctic sea ice loss, notably ozone-depleting substances. When these substances became strictly regulated by the Montreal Protocol Within the late Nineteen Eighties, their atmospheric concentrations began to say no within the mid-Nineteen Nineties.
Polvani and his co-author Mark England, Royal Commission for the Exhibition of 1851 Senior Research Fellow on the University of Exeter and a former PhD student with Polvani, were particularly keen on exploring the impact of ozone-depleting substances because their molecules, while lots less common within the atmosphere, are tens of hundreds of times more powerful at warming the planet than carbon dioxide.
Latest Climate Model Simulations
The researchers analyzed latest climate model simulations and located that the Montreal Protocol is delaying the primary appearance of an ice-free Arctic summer by as much as 15 years, depending on future CO2 emissions. They compared the estimated warming from ozone-depleting substances with and without the Montreal Protocol under two scenarios of future CO2 emissions from 1985–2050. Their results show that if the Montreal Protocol had not been enacted, the estimated global mean surface temperature could be around 0.5 degrees Celsius warmer and the Arctic polar cap could be almost 1 degree Celsius warmer in 2050.
“This essential climate mitigation stems entirely from the reduced greenhouse gas warming from the regulated ozone-depleting substances, with the avoided stratospheric ozone losses playing no role,” said England. “While ozone-depleting substances aren’t as abundant as other greenhouse gasses corresponding to carbon dioxide, they will have an actual impact on global warming. Ozone-depleting substances have particularly powerful effects within the Arctic, they usually were a vital driver of Arctic climate change within the second half of the twentieth Century. While stopping these effects was not the first goal of the Montreal Protocol, it has been a implausible by-product.”
Because the mid-Nineteen Nineties, the Montreal Protocol has successfully reduced atmospheric concentrations of ozone-depleting substances and there are signs that the ozone layer has began to heal. But recent research has suggested a slight rise in ozone-depleting substance concentrations from 2010–2020, and England and Polvani stressed the importance of staying vigilant.
Learn more about Lorenzo Polvani and his research:
