Mitigation of Soot, Refrigerants, Other Short-Lived Pollutants Provides Political Opportunity

Fast cuts to short-lived climate pollutants will provide both short-term climate mitigation as well as the political confidence necessary for a broader international climate deal in Paris in December, according to a Nature Climate Change commentary published today. 

Short-lived climate pollutants include methane, black carbon, hydrofluorocarbons (HFCs), and methane, the main component of smog, or ground-level ozone. 

“Unlike long-lived CO₂ emissions, which remain in the atmosphere for hundreds to thousands of years, short-lived pollutants remain in the atmosphere for just days to a few decades, and cutting them will reduce the rate of warming within a decade,” said co-author Veerabhadran Ramanthan, a distinguished professor of climate and atmospheric sciences at Scripps Institution of Oceanography, UC San Diego, and UNESCO Professor of Climate and Policy, TERI University, Delhi, India.

“The fresh scientific insights about short-lived climate pollutants are opening up a new political front in the battle to mitigate climate change,” said lead author David Victor, a professor at UC San Diego.

“Technologies exist today to reduce up to 30 percent of methane, 75 percent of black carbon, and nearly 100 percent of potent HFCs,” said coauthor Durwood Zaelke, president of the Institute for Governance & Sustainable Development.  “This would avoid up to 0.6°C (1.1° F) of warming by mid-century, in addition to slowing sea-level rise, the melting of glaciers, and the retreat of the Arctic ice cap,” said Ramanathan. 

“Reductions of these short-pollutants will have a huge impact on local ravages of air pollutants, which already kill seven million people every year and degrade more than a hundred million tons of crops,” said Victor. “These are not hypothetical cuts. California has already done this and has a blueprint for the world.”

“The climate impact of HFCs can be cut nearly 100 percent under the Montreal Protocol, widely acknowledged as the world’s most successful environmental treaty, for its success putting the stratospheric ozone layer on the path to recovery as well as for providing significant climate mitigation,” said Zaelke.  “A total of 90 parties to the Montreal Protocol—rich countries and poor, big countries and small – have submitted formal proposals to phase down HFC production and consumption under the Montreal Protocol.”

Countries that participate in the Montreal Protocol include include the island coalition led by the Federated States of Micronesia, the first country to propose cutting HFCs, along with the U.S., Canada, and Mexico, the EU-28, the Africa Group of 55 countries, and India.  The amendment to reduce short-lived pollutants could pass as early as November this year, although opposition remains from the Gulf States. 

“Slowing climate change requires fast action on additional fronts beyond the U.N. climate process,” said Victor. “Near-term progress is more likely to occur when using a portfolio of decentralized strategies that work on many different fronts.  Action on short-lived climate pollutants will raise the odds that this time, the world will develop the confidence to get serious on climate action.”

The Climate and Clean Air Coalition to Reduce Short-Lived Climate Pollutants (CCAC) currently supports government and NGO representatives working to reduce black carbon from cooking stoves, brick kilns, and diesel vehicles, as well as methane, and HFC reductions. The CCAC recently released a guidance note on short-lived climate pollutant mitigation strategies to aid countries in developing their intended nationally determined contributions (INDCs) leading up to Paris. Mexico, the U.S., and most recently China, have released INDCs that include short-lived climate pollutants. Chile has indicated it will follow suit. 

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