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| Titel |
Radiative forcing and climate response to projected 21st century aerosol decreases |
| VerfasserIn |
D. M. Westervelt, L. W. Horowitz, V. Naik, J.-C. Golaz, D. L. Mauzerall |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 22 ; Nr. 15, no. 22 (2015-11-16), S.12681-12703 |
| Datensatznummer |
250120163
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| Publikation (Nr.) |
 copernicus.org/acp-15-12681-2015.pdf |
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| Zusammenfassung |
| It is widely expected that global emissions of atmospheric aerosols and
their precursors will decrease strongly throughout the remainder of the
21st century, due to emission reduction policies enacted to protect
human health. For instance, global emissions of aerosols and their
precursors are projected to decrease by as much as 80 % by the year 2100,
according to the four Representative Concentration Pathway (RCP) scenarios.
The removal of aerosols will cause unintended climate consequences,
including an unmasking of global warming from long-lived greenhouse gases.
We use the Geophysical Fluid Dynamics Laboratory Coupled Climate Model
version 3 (GFDL CM3) to simulate future climate over the 21st century
with and without the aerosol emission changes projected by each of the RCPs
in order to isolate the radiative forcing and climate response resulting
from the aerosol reductions. We find that the projected global radiative
forcing and climate response due to aerosol decreases do not vary
significantly across the four RCPs by 2100, although there is some
mid-century variation, especially in cloud droplet effective radius, that
closely follows the RCP emissions and energy consumption projections. Up to
1 W m−2 of radiative forcing may be unmasked globally from 2005 to 2100
due to reductions in aerosol and precursor emissions, leading to average
global temperature increases up to 1 K and global precipitation rate
increases up to 0.09 mm day−1. However, when using a version of
CM3 with reduced present-day aerosol radiative forcing (−1.0 W m−2),
the global temperature increase for RCP8.5 is about 0.5 K, with similar
magnitude decreases in other climate response parameters as well. Regionally
and locally, climate impacts can be much larger than the global mean, with a
2.1 K warming projected over China, Japan, and Korea due to the reduced
aerosol emissions in RCP8.5, as well as nearly a 0.2 mm day−1
precipitation increase, a 7 g m−2 LWP decrease, and a 2 μm
increase in cloud droplet effective radius. Future aerosol decreases could
be responsible for 30–40 % of total climate warming (or 10–20 % with
weaker aerosol forcing) by 2100 in East Asia, even under the high greenhouse
gas emissions scenario (RCP8.5). The expected unmasking of global warming
caused by aerosol reductions will require more aggressive greenhouse gas
mitigation policies than anticipated in order to meet desired climate
targets. |
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