The regional temperature implications of strong air quality measures

• 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: Physics; QC1-999; Chemistry; QD1-999; Arctic; black carbon
• Online Access: https://doi.org/10.5194/acp-19-15235-2019; https://doaj.org/article/713261af8da14dbeaf0d463861b047f4

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., ...