Local and remote mean and extreme surface temperature response to regional aerosol emissions reductions in three coupled chemistry-climate models
Abstract
The unintended climatic implications of regional aerosol and precursor emissions reductions implemented to protect human health are poorly understood. We investigate the mean and extreme temperature response to regional changes in aerosol emissions using three coupled chemistry-climate models: NOAA GFDL-CM3, NCAR-CESM1, and NASA GISS-E2. Our approach contrasts a long present-day control simulation from each model (up to 400 years with perpetual year 2000 or 2005 emissions) with fourteen individual aerosol emissions perturbation simulations (160-240 years each). We perturb emissions of sulfur dioxide (SO2) and/or carbonaceous aerosol within six world regions and assess the statistical significance of mean and extreme temperature responses relative to internal variability determined by the control simulation and across the models. In all models, the global mean surface temperature response (perturbation minus control) is mostly positive (warming), statistically significant, and ranges from +0.17 K (Europe SO2) to -0.06 K (US BC). The warming response to SO2 is strongest in the US and Europe perturbation simulations, both globally and regionally, with Arctic warming up to 1 K due to a removal of European anthropogenic SO2 emissions alone; however, even emissions from regions remote to the Arctic, such as Indian SO2, can result in significant Arctic warming up to 0.5 K. The temperature response in the northern hemisphere mid-latitudes is most sensitive to emissions perturbations within that region. In the tropics, however, the temperature response to emissions perturbations is roughly the same in magnitude as the temperature response to emissions perturbations remote to the tropics. Arctic warming is the most robust model response across each model and several aerosol emissions perturbations. We find that climate sensitivity to aerosol perturbations differs both across our perturbation simulations and from the 2xCO2 equilibrium climate sensitivity (see attached figure). We find a mean shift in the surface temperature distribution in each model both globally and regionally, which increases upper-tail extreme temperature events in response to aerosol perturbations. The correlation between mean and extreme surface temperature responses suggests a functional relationship between the two.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A51S2880W
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0320 Cloud physics and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0321 Cloud/radiation interaction;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSES;
- 3311 Clouds and aerosols;
- ATMOSPHERIC PROCESSES;
- 3354 Precipitation;
- ATMOSPHERIC PROCESSES