The regional temperature implications of strong air quality measures

Anthropogenic emissions of short-lived climate forcers (SLCFs) affect both air quality and climate. How much regional temperatures are affected by ambitious SLCF emission mitigation policies is, however, still uncertain. We investigate the potential temperature implications of stringent air quality...

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Bibliographic Details
Published in:Atmospheric Chemistry and Physics
Main Authors: B. Aamaas, T. K. Berntsen, B. H. Samset
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2019
Subjects:
Online Access:https://doi.org/10.5194/acp-19-15235-2019
https://doaj.org/article/713261af8da14dbeaf0d463861b047f4
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Summary:Anthropogenic emissions of short-lived climate forcers (SLCFs) affect both air quality and climate. How much regional temperatures are affected by ambitious SLCF emission mitigation policies is, however, still uncertain. We investigate the potential temperature implications of stringent air quality policies by applying matrices of regional temperature responses to new pathways for future anthropogenic emissions of aerosols, methane ( CH 4 ), and other short-lived gases. These measures have only a minor impact on CO 2 emissions. Two main options are explored, one with climate optimal reductions (i.e., constructed to yield a maximum global cooling) and one with the maximum technically feasible reductions. The temperature response is calculated for four latitude response bands (90–28 ∘ S, 28 ∘ S–28 ∘ N, 28–60 ∘ N, and 60–90 ∘ N) by using existing absolute regional temperature change potential (ARTP) values for four emission regions: Europe, East Asia, shipping, and the rest of the world. By 2050, we find that global surface temperature can be reduced by <math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>-</mo><mn mathvariant="normal">0.3</mn><mo>±</mo><mn mathvariant="normal">0.08</mn></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="58pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="57ecb62e399fb769f244ac0e41de3edd"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-15235-2019-ie00001.svg" width="58pt" height="10pt" src="acp-19-15235-2019-ie00001.png"/></svg:svg> ∘ C with climate-optimal mitigation of SLCFs relative to a baseline scenario and as much as −0.7 ∘ C in the Arctic. Cutting CH 4 and black carbon (BC) emissions contributes the most. The net global cooling could offset warming equal to approximately 15 years of current global CO 2 emissions. On the other hand, mitigation of other SLCFs (e.g., ...