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| Titel |
Have tropospheric aerosol emissions contributed to the recent climate hiatus? |
| VerfasserIn |
Thomas Kühn, Antti-Ilari Partanen, Anton Laakso, Zifeng Lu, Tommi Bergman, Santtu Mikkonen, Harri Kokkola, Hannele Korhonen, Petri Räisänen, David G. Streets, Sami Romakkaniemi, Ari Laaksonen |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250098631
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| Publikation (Nr.) |
 EGU/EGU2014-14326.pdf |
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| Zusammenfassung |
| During the last 15 years global warming has slowed considerably, with the resulting plateau
in global temperature records being dubbed the climate hiatus. Apart from variations in solar
irradiance and ocean temperature, increased anthropogenic aerosol emissions in South and
East Asia have been suggested as possible causes for this hiatus. While European
and and North American aerosol emissions have constantly decreased since the
1980’s, emissions in China and India have started increasing at the same time and,
although total global aerosol emissions have decreased, aerosol effects on the global
energy budget are expected to enhance towards the equator due to stronger irradiance
there.
In this study we used the aerosol-climate model ECHAM5-HAM2 to assess the effect
that this re-distribution of anthropogenic aerosol emissions towards the equator
may have on climate. To this end, we computed radiative forcing and equilibrium
temperature response due to the change in global aerosol emissions (black carbon
(BC), organic carbon and sulphur dioxide) between 1996 and 2010, keeping all
other anthropogenic influences fixed. Surprisingly we found that the cooling due
the increased aerosol emissions in China and India is almost negligible compared
to the warming caused by the decreasing aerosol emissions in Europe and North
America. The radiative flux perturbation (RFP; includes aerosol indirect effects) was
0.42 W-m2 and the change in global equilibrium 2m temperature increased by
0.25°C.
The lack of cooling in China and India stems from a cancellation of sulfate cooling and
BC warming, especially over China. There, the strong cloud cover leads to both attenuation
of sulphate aerosol light scattering and saturation tendency of indirect aerosol effects
on clouds. BC levels on the other hand increase also above the clouds (relative
increase of BC levels is almost uniform with height), leading to warming through light
absorption. |
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