Study co-authored by Georgetown’s Dr. Gabrielle Dreyfus clarifies the need for comprehensive CO2 and non-CO2 mitigation approaches to address both near-term and long-term warming

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Dr. Gabrielle Dreyfus

New study shows that only with a dual assault on carbon dioxide and other largely neglected climate pollutants will it be possible to keep the 1.5°C guardrail in sight and stay below 2°C. 

Published May 23 by the Proceedings of the National Academy of Sciences ( (new window)), the study is the first to analyze the importance of cutting non-carbon dioxide climate pollutants vis a vis merely reducing fossil fuel emissions, in both the near-term and mid-term to 2050. It confirms increasing fears that the present almost exclusive focus on carbon dioxide cannot by itself prevent global temperatures from exceeding 1.5°C above pre-industrial levels, the internationally accepted guardrail beyond which the world’s climate is expected to pass irreversible tipping points. The study – by scientists at Georgetown University, Texas A&M University, Scripps Institution of Oceanography at UC San Diego, and others – concludes that adopting a “dual strategy” that simultaneously reduces emissions of both carbon dioxide and the other climate pollutants would cut the rate of warming in half by 2050, making it much more likely to stay within these limits.

The non-carbon dioxide pollutants include methane, hydrofluorocarbon refrigerants, black carbon soot, ground-level ozone smog, as well as nitrous oxide. The study calculates that together these pollutants currently contribute almost as much to global warming as carbon dioxide. Since most of them last only a short time in the atmosphere, cutting them slows warming faster than any other mitigation strategy.

Dr. Gabrielle Dreyfus, adjunct faculty with the Department of Physics and lead author of the study, told reporters:

 “This is an optimistic message, as we have low or no-cost strategies available, with no or low-cost interventions, that can slow global warming in the critical near-term.” – Dr Gabrielle Dreyfus, The Guardian. ( (new window))

 “We’re simultaneously in two races to avert climate catastrophe. We have to win the sprint to slow warming in the near term by tackling the short-lived climate pollutants so that we can stay in the race to win the marathon against CO2.” – Dr Gabrielle Dreyfus, Inside Climate News. ( (new window))