It's Time to Broaden the Strategy to Avert Catastrophic Climate Change

Slashing emissions of carbon dioxide, by itself, cannot prevent catastrophic global warming. But a new study concludes that a strategy that simultaneously reduces emissions of other largely neglected climate pollutants, like methane, would cut the rate of global warming in half and give the world a fighting chance to keep the climate safe for humanity.

Co-authored by Drew Shindell, Chair of the Climate and Clean Air Coalition Scientific Advisory Panel, and others, the study calculates that the non-carbon dioxide pollutants - methane, hydrofluorocarbon refrigerants, black carbon soot, ground-level ozone smog, as well as nitrous oxide - together 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.

Until now, however, the importance of these non-carbon dioxide pollutants has been underappreciated by scientists and policymakers alike and largely neglected in efforts to combat climate change.

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. The report confirms increasing fears that the present almost exclusive focus on carbon dioxide cannot by itself prevent global temperatures from exceeding 1.5°C, the internationally accepted guardrail beyond which the world's climate is expected to pass irreversible tipping points.

Indeed, such decarbonization alone would be unlikely to stop temperatures from exceeding even the much more hazardous 2°C limit.

The study concludes that adopting a “dual strategy” that simultaneously reduces emissions of both carbon dioxide and other climate pollutants would cut the rate of warming in half by 2050, making it much more likely to stay within these limits.

Drew Shindell, Professor of Earth Science, Nicholas School of the Environment, Duke University & Chair of the CCAC Scientific Advisory Panel:

Decarbonization is crucial to meeting our long-term climate goals, but it’s not enough – to slow warming in the near-term and reduce suffering from the ever increasing heatwaves, droughts, superstorms, and fires we need to also reduce short-lived climate pollutants this decade.

Rick Duke, Deputy Special Envoy on Climate Change & Co-chair of the CCAC:

This study affirms that mitigating methane and other short-lived climate pollutants is the best way to slow the rate of warming in the near term. Rapid, targeted action to address these gases is critical to keep a safer 1.5°C trajectory within reach and avoid potentially irreversible tipping points. Decarbonization alone will not be enough. This is why the U.S. and EU launched the Global Methane Pledge at COP26 to reduce anthropogenic methane emissions at least 30% by 2030 from 2020 levels. The world must now deliver on this target in order to avoid the worst impacts of climate change.

Martina Otto, Head of the CCAC Secretariat:

Cutting methane and other short-lived climate pollutants is our best option to slow climate change over the next 25 years. Of course, this is not a substitute for the needed transition to a net-zero world. This study shows exactly that – we need a dual strategy. We must commit to no new fossil fuel infrastructure and simultaneously act decisively to reduce methane and other SLCP emissions. The future of our people and planet depends upon it.

The study highlights the importance of the CCAC’s mission, in particular its emphasis on methane mitigation. In May 2021 the CCAC and UNEP’s Global Methane Assessment found that human-caused methane emissions can be reduced by up to 45 per cent this decade and such reductions would avoid nearly 0.3°C of global warming by 2045.

Next month, at the end of September, the CCAC, in collaboration with the Global Methane Initiative will host the Global Methane, Climate and Clean Air Forum bringing together policymakers, industry leaders, technical experts, and researchers from around the world to discuss opportunities to protect the climate and improve air quality with a special focus on methane.

Indeed tackling both carbon dioxide and the short-lived pollutants at the same time offers the best and the only hope of humanity making it to 2050 without triggering irreversible and potentially catastrophic climate change.

The paper, Mitigating Climate Disruption in Time: a self-consistent approach for avoiding both near-term and long-term global warming, is available here. A summary of the paper by the authors is here.