The story of threats to the ozone layer didn't end with CFCs. Professor Susan Solomon and graduate student Megan Lickley receive funding from the Volo Foundation to assess the risks of HFC and HCFC emissions, and their potential impact on global warming.

In the 1980s, Susan Solomon, now the EAPS Lee and Geraldine Martin Professor of Environmental Studies, was part of a team that identified the primary agent responsible for degrading the Earth’s ozone layer and affecting its climate: a type of halocarbon, chlorofluorocarbons (CFCs). The scientific evidence that she helped provide ultimately led to a global production phase out of halocarbons like CFCs with the establishment of the Montreal Protocol. To date, this has been the most effective policy measure for mitigating both ozone depletion and global warming. Since then she’s been tracking the ozone hole’s recovery and the effects these halocarbon emissions are having on the climate system.

However, the problem didn’t end there. Halocarbons like chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs) still exist around the world, residing in refrigeration units at risk of leaking—still threatening the ozone layer. Further, these compounds are potent greenhouse gases. Per pound, CFC-12 has 11,000-times more global warming potential than CO₂ over a hundred years. But scientists don’t yet know how much still exists, what their impact on climate change could be if released, and the benefits of capturing them before then.

Given the potential for harm, and the possibility of finding a solution backed up by scientific data, the VoLo Foundation (established by David S. Vogel ‘95 (XVIII) and Thais Lopez Vogel) is funding a new study led by Susan Solomon and EAPS graduate student Megan Lickley. They’ll analyze the amount of halocarbons at risk of escaping and quantify the potential impact of policies to capture, manage, and recycle these halocarbons in order to prevent emission into the atmosphere.

“It is clear that avoiding halocarbon emission is a powerful tool for climate change mitigation,” says Solomon. “There is an urgent need to take action: each year these halocarbon banks are not managed means more emission to the atmosphere and more warming impact. If this problem is not addressed soon, the opportunity to prevent further harm will be squandered.” 

Since the Montreal Protocol parties are now discussing these remaining halocarbon “banks,” the study will provide critical data for scientifically-supported decision making. Further, it analyzes how much further protection the climate system could have gained had authorities chosen to control CFC banks in the U.S. and Europe earlier. It will also assess the size of the HCFC banks currently held in the U.S., China, and India; their potential impact upon global warming; and determine viable solutions.

“This bank of halocarbons represents a unique target for mitigating climate change (and further protecting the ozone layer in the case of CFCs and HCFCs),” says Abigail Axelrod, Program Officer of the VoLo Foundation. “And Solomon’s study will help to show how important such steps could be.”

Read more about Solomon's research:
https://eapsweb.mit.edu/people/solos

Story Image: False-color view of the monthly-averaged total ozone over the Antarctic pole for October 2018. Blues and purples indicate where there is the least ozone, yellows and reds indicate where there is more ozone. Image credit: NASA Goddard Flight Center