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A new study concludes that cutting carbon dioxide emissions (CO2) alone cannot resolve the deepening climate catastrophe. Only a dual strategy that simultaneously reduces CO2 emissions and other even more potent climate super pollutants will ensure we keep within the 1.5°C guardrail of global warming established by the Paris Agreement beyond which climate change and its devastating impacts may simply be irreversible.
Proceedings of the National Academy of Sciences (PNAS) published a 2022 study led by Dr. Dreyfus, the Chief Scientist at the Institute for Governance & Sustainable Development (IGSD) and Professor at Georgetown University, analyzing the importance of reducing non-carbon dioxide climate pollutants, state that mitigation measures targeting only decarbonization benefit long-term cooling, but at the expense of short-term warming due to the unmasked cooling effect of co-emitted aerosols. If we only prioritize carbon dioxide emissions, global temperatures will exceed 2˚C by 2050, which will result in increased risk of surpassing irreversible tipping points that the climate system will not be able to recover from.
According to Dr. Dreyfus, “The IPCC says we must make deep cuts to GHG immediately. Our study shows that phasing out fossil fuels is essential but must be paired with targeted action now on methane, black carbon soot, HFCs, and smog. This dual strategy is the only way to slow warming over the next two decades and give ourselves a fighting chance for a livable climate.” IGSD Latest News, 23 May 2022.
As recognized in the study, reports from the Intergovernmental Panel on Climate Change further discourage solely focusing on carbon dioxide because the process of decarbonizing the energy system and shifting to clean energy actually worsens short-term global warming. Since burning fossil fuels also emits sulfate aerosols that work to cool the planet, cutting carbon dioxide emissions has the ironic short term effect of warming the climate before we see any cooling benefits reaped in the longer term. These cooling sulfates only stay within the atmosphere for a short period of time (within days to weeks), while carbon dioxide lasts hundreds of years, thus leading to an overall warming in the short term in deep decarbonization strategies alone. Hence, focusing exclusively on reducing carbon dioxide emissions could result in “weak, near term warming” which could potentially cause temperatures to exceed the 1.5˚C limit by 2035.
The dual strategy of combining decarbonization and non-CO2 pollutants can provide net cooling by 2030, which reduces the rate of warming by approximately 50% by 2050. These non-CO2 climate pollutants mostly consist of methane (natural gas), hydrofluorocarbon refrigerants (dirty refrigerants), black carbon (soot), and ozone (smog) that are commonly referred to as short-lived climate pollutants (SLCP). SLCPs contribute from 43 to 48 percent of global warming and remain in the atmosphere for a much shorter time period than carbon dioxide. The importance of reducing SLCPs in climate mitigation has been underrepresented, as it is the fastest near-term solution. Reducing SLCP emissions and nitrous oxide slows global warming faster than any other strategy since these pollutants remain in the atmosphere for a much shorter time than carbon dioxide and their potency greatly exceeds that of CO2 . Both these characteristics make reducing SLCPs the quickest solution to addressing the climate catastrophe by 2050.
Adopting both carbon dioxide with SLCP and nitrous oxide mitigation measures offers the best solution in ensuring we remain on track with/limit overshoot of the 1.5˚C threshold and that we do not surpass irreversible tipping points in the upcoming decades.
“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.
Link to article: https://www.pnas.org/doi/full/10.1073/pnas.2123536119