Title: Reaching 1.5 and 2.0 °C global surface temperature targets using stratospheric aerosol geoengineering

Abstract

A new set of stratospheric aerosol geoengineering (SAG) model experiments has been performed with Community Earth System Model version 2 (CESM2) with the Whole Atmosphere Community Climate Model (WACCM6) that are based on the Coupled Model Intercomparison Project phase 6 (CMIP6) overshoot scenario (SSP5-34-OS) as a baseline scenario to limit global warming to 1.5 or 2.0 °C above 1850–1900 conditions. The overshoot scenario allows us to applying a peak-shaving scenario that reduces the needed duration and amount of SAG application compared to a high forcing scenario. In addition, a feedback algorithm identifies the needed amount of sulfur dioxide injections in the stratosphere at four pre-defined latitudes, 30 °N, 15 °N, 15 °S, and 30 °S, to reach three surface temperature targets: global mean temperature, and interhemispheric and pole-to-Equator temperature gradients. These targets further help to reduce side effects, including overcooling in the tropics, warming of high latitudes, and large shifts in precipitation patterns. These experiments are therefore relevant for investigating the impacts on society and ecosystems. Comparisons to SAG simulations based on a high emission pathway baseline scenario (SSP5-85) are also performed to investigate the dependency of impacts using different injection amounts to offset surface warming by SAG. We find that changes from present-day conditions around 2020 in some variablesmore » depend strongly on the defined temperature target (1.5 °C vs. 2.0 °C). These include surface air temperature and related impacts, the Atlantic Meridional Overturning Circulation, which impacts ocean net primary productivity, and changes in ice sheet surface mass balance, which impacts sea level rise. Others, including global precipitation changes and the recovery of the Antarctic ozone hole, depend strongly on the amount of SAG application. Furthermore, land net primary productivity as well as ocean acidification depend mostly on the global atmospheric CO₂ concentration and therefore the baseline scenario. Multi-model comparisons of experiments that include strong mitigation and carbon dioxide removal with some SAG application are proposed to assess the robustness of impacts on societies and ecosystems.« less

Authors:

Tilmes, Simone ^[1]; MacMartin, Douglas G.  ^[2];

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Lenaerts, Jan T. M.  ^[3];

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van Kampenhout, Leo ^[4]; Muntjewerf, Laura  ^[5];

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Xia, Lili ^[6]; Harrison, Cheryl S. ^[7]; Krumhardt, Kristen M.  ^[1];

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Mills, Michael J.  ^[1];

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Kravitz, Ben  ^[8];

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Robock, Alan  ^[6]

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• Search DOE PAGES for ORCID "0000-0002-6319-5656"

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+ Show Author Affiliations

1. National Center for Atmospheric Research, Boulder, CO (United States)
2. Cornell University, Ithaca, NY (United States)
3. University of Colorado, Boulder, CO (United States)
4. Utrecht University (Netherlands)
5. Delft University of Technology (Netherlands)
6. Rutgers University, New Brunswick, NJ (United States)
7. University of Texas Rio Grande Valley, Port Isabel, TX (United States)
8. Indiana University, Bloomington, IN (United States); Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

Publication Date:

Tue Jul 14 00:00:00 EDT 2020

Research Org.:

Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

Sponsoring Org.:

USDOE; National Science Foundation (NSF)

OSTI Identifier:

1673310

Report Number(s):

PNNL-SA-152096
Journal ID: ISSN 2190-4987

Grant/Contract Number:  

AC05-76RL01830; AGS-1617844; 1852977

Resource Type:

Accepted Manuscript

Journal Name:

Earth System Dynamics (Online)

Additional Journal Information:

Journal Name: Earth System Dynamics (Online); Journal Volume: 11; Journal Issue: 3; Journal ID: ISSN 2190-4987

Publisher:

European Geosciences Union

Country of Publication:

United States

Language:

English

Subject:

42 ENGINEERING