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Title: Nonlinear Climate Responses to Increasing CO 2 and Anthropogenic Aerosols Simulated by CESM1

Abstract

Atmospheric CO 2 and anthropogenic aerosols (AA) have increased simultaneously. Because of their opposite radiative effects, these increases may offset each other, which may lead to some nonlinear effects. Here the seasonal and regional characteristics of this nonlinear effect from the CO 2 and AA forcings are investigated using the fully coupled Community Earth System Model. Results show that nonlinear effects are small in the global mean of the top-of-the-atmosphere radiative fluxes, surface air temperature, and precipitation. However, significant nonlinear effects exist over the Arctic and other extratropical regions during certain seasons. When both forcings are included, Arctic sea ice in September–November decreases less than the linear combination of the responses to the individual forcings due to a higher sea ice sensitivity to the CO 2 -induced warming than the sensitivity to the AA-induced cooling. This leads to less Arctic warming in the combined-forcing experiment due to reduced energy release from the Arctic Ocean to the atmosphere. Some nonlinear effects on precipitation in June–August are found over East Asia, with the northward-shifted East Asian summer rain belt to oppose the CO 2 effect. In December–February, the aerosol loading over Europe in the combined-forcing experiment is higher than that due tomore » the AA forcing, resulting from CO 2 -induced circulation changes. The changed aerosol loading results in regional thermal responses due to aerosol direct and indirect effects, weakening the combined changes of temperature and circulation. This study highlights the need to consider nonlinear effects from historical CO 2 and AA forcings in seasonal and regional climate attribution analyses.« less

Authors:
ORCiD logo [1];  [2];  [3]
  1. Key Laboratory of Meteorological Disaster, Ministry of Education/Joint International Research Laboratory of Climate and Environmental Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing, China, and Department of Atmospheric and Environmental Sciences, University at Albany, State University of New York, Albany, New York
  2. Department of Atmospheric and Environmental Sciences, University at Albany, State University of New York, Albany, New York
  3. Key Laboratory of Meteorological Disaster, Ministry of Education/Joint International Research Laboratory of Climate and Environmental Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing, China
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1577925
Grant/Contract Number:  
SC0012602
Resource Type:
Published Article
Journal Name:
Journal of Climate
Additional Journal Information:
Journal Name: Journal of Climate Journal Volume: 33 Journal Issue: 1; Journal ID: ISSN 0894-8755
Publisher:
American Meteorological Society
Country of Publication:
United States
Language:
English

Citation Formats

Deng, Jiechun, Dai, Aiguo, and Xu, Haiming. Nonlinear Climate Responses to Increasing CO 2 and Anthropogenic Aerosols Simulated by CESM1. United States: N. p., 2020. Web. doi:10.1175/JCLI-D-19-0195.1.
Deng, Jiechun, Dai, Aiguo, & Xu, Haiming. Nonlinear Climate Responses to Increasing CO 2 and Anthropogenic Aerosols Simulated by CESM1. United States. doi:10.1175/JCLI-D-19-0195.1.
Deng, Jiechun, Dai, Aiguo, and Xu, Haiming. Wed . "Nonlinear Climate Responses to Increasing CO 2 and Anthropogenic Aerosols Simulated by CESM1". United States. doi:10.1175/JCLI-D-19-0195.1.
@article{osti_1577925,
title = {Nonlinear Climate Responses to Increasing CO 2 and Anthropogenic Aerosols Simulated by CESM1},
author = {Deng, Jiechun and Dai, Aiguo and Xu, Haiming},
abstractNote = {Atmospheric CO 2 and anthropogenic aerosols (AA) have increased simultaneously. Because of their opposite radiative effects, these increases may offset each other, which may lead to some nonlinear effects. Here the seasonal and regional characteristics of this nonlinear effect from the CO 2 and AA forcings are investigated using the fully coupled Community Earth System Model. Results show that nonlinear effects are small in the global mean of the top-of-the-atmosphere radiative fluxes, surface air temperature, and precipitation. However, significant nonlinear effects exist over the Arctic and other extratropical regions during certain seasons. When both forcings are included, Arctic sea ice in September–November decreases less than the linear combination of the responses to the individual forcings due to a higher sea ice sensitivity to the CO 2 -induced warming than the sensitivity to the AA-induced cooling. This leads to less Arctic warming in the combined-forcing experiment due to reduced energy release from the Arctic Ocean to the atmosphere. Some nonlinear effects on precipitation in June–August are found over East Asia, with the northward-shifted East Asian summer rain belt to oppose the CO 2 effect. In December–February, the aerosol loading over Europe in the combined-forcing experiment is higher than that due to the AA forcing, resulting from CO 2 -induced circulation changes. The changed aerosol loading results in regional thermal responses due to aerosol direct and indirect effects, weakening the combined changes of temperature and circulation. This study highlights the need to consider nonlinear effects from historical CO 2 and AA forcings in seasonal and regional climate attribution analyses.},
doi = {10.1175/JCLI-D-19-0195.1},
journal = {Journal of Climate},
number = 1,
volume = 33,
place = {United States},
year = {2020},
month = {1}
}

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