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Study Confirms Need to Cut CO2 as Well as Short-Lived Pollutants Can’t Afford to Wait on Either


Washington DC, November 21, 2013: A paper published today in Nature Climate Change confirms earlier studies finding that immediate and aggressive cuts in both carbon dioxide (CO2) and short-lived climate pollutants (SLCPs) are necessary to maintain global temperatures below 2°C through the end of the century.

This confirms earlier research by Dr. V. Ramanathan of Scripps Institution of Oceanography, Dr. Drew Shindell at the NASA Goddard Institute of Space Studies, and others that mitigation of three of the four SLCPs, black carbon, methane, and tropospheric ozone, would lead to about 0.5 to 0.6°C of avoided warming, but without aggressive and immediate cuts in CO2 temperatures would continue to rise through the end of century and beyond.

“The benefits of cutting SLCPs are considerably greater when the calculations include the near term benefits from reducing the other SLCP, hydrofluorocarbons, or HFCs, used as refrigerants, as this could avoid as much as an additional 0.5°C of warming by the end of the century,” according to Durwood Zaelke, President of the Institute for Governance & Sustainable Development. “Phasing down HFCs under the Montreal Protocol is probably the single biggest, fastest, and cheapest piece of mitigation in the near-term and through 2100, but HFCs unfortunately were not include in this study.”

“The real challenge for both CO2 and SLCPs is not the science, but rather the politics of how to get the reductions,” Zaelke said. “There is a profound difference between knowing what to do and figuring out how to get it done.”

“California, for example, reduced its black carbon emissions by 90%, according to a recent study lead by Dr. Ramanathan,” Zaelke added. This contrasts with the 58% increase in CO2 since 1990 reported this week by the Global Carbon Budget. (1990 is the reference year for the Kyoto Protocol climate treaty.)

“The politics of SLCP mitigation are encouraging,” Zaelke said, “in part because of the significant collateral benefits for health and agriculture, and in part because they can be reduced with existing technologies and in most cases with existing laws and institutions, without waiting for the UN climate negotiations to conclude a new treaty that is expected to come into force in 2020.”

The new study notes the collateral benefits from SLCP mitigation, and it also mentions the argument that success with the SLCPs can build political momentum for CO2 mitigation.

“The SLCP advocates know that CO2 mitigation is essential, but also know that we're at COP 19 and CO2 emissions have been going in the wrong direction for these past 19 years.”

“We need to be more sophisticated politically, so we can learn how to solve the parts of the climate problem that we can solve today, while we continue to develop both the technologies and the political will to solve other parts,” argued Zaelke.

The new paper conclude that “Immediate action on SLCPs might potentially ‘buy time’ for adaptation by reducing near-term warming,” a point of tremendous importance to all the vulnerable peoples and places already suffering climate impacts.”


For more information on the importance of simultaneous cuts in CO2 and SLPCs see IGSD’s Primer on SLCPs here.

See also IGSD’s Primer on HFCs here.

The California black carbon study is here.