Arctic Melting Away

A brand new examine exhibits that half of all Arctic warming and corresponding sea-loss throughout the late 20th century was brought on by ozone-depleting substances. Right here, icebergs discharged from Greenland’s Jakobshavn Glacier. Credit score: Kevin Krajick/Earth Institute

Implicated in a Third of Total World Warming for the Time Interval

A scientific paper revealed in 1985 was the primary to report a burgeoning gap in Earth’s stratospheric ozone over Antarctica. Scientists decided the trigger to be ozone-depleting substances – long-lived synthetic halogen compounds. Though the ozone-destroying results of those substances at the moment are broadly understood, there was little analysis into their broader local weather impacts.

A examine revealed in the present day (January 20, 2020) in Nature Local weather Change by researchers at Columbia College examines the greenhouse warming results of ozone-depleting substances and finds that they induced a few third of all international warming from 1955 to 2005, and half of Arctic warming and sea ice loss throughout that interval. They thus acted as a robust complement to carbon dioxide, essentially the most pervasive greenhouse gasoline; their results have since began to fade, as they’re now not produced and slowly dissolve.

Ozone-depleting substances, or ODS, have been developed within the 1920s and ’30s and have become popularly used as refrigerants, solvents, and propellants. They’re fully artifical, and so didn’t exist within the environment earlier than this time. Within the 1980s a gap in Earth’s stratospheric ozone layer, which filters a lot of the dangerous ultraviolet radiation from the solar, was found over Antarctica. Scientists shortly attributed it to ODS.

The world sprang into motion, finalizing a world settlement to section out ODS. The Montreal Protocol, as it’s known as, was signed in 1987 and entered into drive in 1989. As a result of swift worldwide response, atmospheric concentrations of most ODS peaked within the late 20th century and have been declining since. Nonetheless, for a minimum of 50 years, the local weather impacts of ODS have been in depth, as the brand new examine reveals.

Scientists at Columbia’s Faculty of Engineering and Utilized Science and the Lamont-Doherty Earth Observatory used local weather fashions to know the consequences of ODS on Arctic local weather. “We showed that ODS have affected the Arctic climate in a substantial way,” mentioned Lamont-Doherty researcher Michael Previdi. The scientists reached their conclusion utilizing two very totally different local weather fashions which might be broadly employed by the scientific neighborhood, each developed on the U.S. Nationwide Heart for Atmospheric Analysis.

The outcomes spotlight the significance of the Montreal Protocol, which has been signed by practically 200 nations, say the authors. “Climate mitigation is in action as we speak because these substances are decreasing in the atmosphere, thanks to the Montreal Protocol,” mentioned Lorenzo Polvani, lead creator of the examine and a professor in Columbia’s Division of Utilized Physics and Utilized Arithmetic. “In the coming decades, they will contribute less and less to global warming. It’s a good-news story.”

Reference: “Substantial twentieth-century Arctic warming caused by ozone-depleting substances” by L. M. Polvani, M. Previdi, M. R. England, G. Chiodo and Okay. L. Smith, 20 January 2020, Nature Local weather Change.
DOI: 10.1038/s41558-019-0677-4

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