*Reaching 1.5 and 2.0 °C global surface temperature targets using
stratospheric aerosol geoengineering*, by Tilmes et al.
https://esd.copernicus.org/articles/11/579/2020/
*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 variables
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 CO_2
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.
How to cite.
Tilmes, S., MacMartin, D. G., Lenaerts, J. T. M., van Kampenhout, L.,
Muntjewerf, L., Xia, L., Harrison, C. S., Krumhardt, K. M., Mills, M.
J., Kravitz, B., and Robock, A.: Reaching 1.5 and 2.0 °C global surface
temperature targets using stratospheric aerosol geoengineering, Earth
Syst. Dynam., 11, 579–601, https://doi.org/10.5194/esd-11-579-2020, 2020.
--
Alan
Alan Robock, Distinguished Professor
Associate Editor, Reviews of Geophysics
Department of Environmental Sciences Phone: +1-848-932-5751
Rutgers University E-mail: rob...@envsci.rutgers.edu
14 College Farm Road http://people.envsci.rutgers.edu/robock
New Brunswick, NJ 08901-8551 USA ☮ http://twitter.com/AlanRobock
--
You received this message because you are subscribed to the Google Groups
"geoengineering" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to geoengineering+unsubscr...@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/geoengineering/4c37f2e7-97c3-2848-01d3-1a7b53fc5f97%40envsci.rutgers.edu.