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| Titel |
Separation of radiative feedback contributions to polar amplification |
| VerfasserIn |
P. L. Langen, T. Mauritsen, R. G. Graversen |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250064156
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| Zusammenfassung |
| When the climate system is forced by a doubling of the atmospheric CO2 content, a number
of feedback processes are induced, such as changes of water vapor, clouds and surface
albedo. Here the CO2 forcing and concomitant feedbacks are studied individually using the
general circulation models NCAR CAM3 and ECHAM 6.0 coupled to mixed layer oceans. A
technique for fixing the radiative effects of moisture, clouds and surface albedo by re-using
these variables from 1ÃCO2 and 2ÃCO2 equilibrium climates in the models’ radiation codes
allows for a detailed decomposition of the problem in terms of forcings, feedbacks
and their responses. The water vapor radiative feedback is found to approximately
double the climate sensitivity, but while its radiative effect is strongly amplified at
low latitudes, the resulting climate response displays about the same degree of
polar amplification as the full all-feedbacks experiment. We conclude that while the
water vapor feedback does not in itself lead to polar amplification by increasing
the ratio of high- to low-latitude warming, it does double climate sensitivity both
at low and high latitudes. In this manner, a polar amplification induced by other
feedbacks in the system, such as the Planck, lapse rate and surface albedo feedbacks, is
strengthened in the sense of increasing the difference in high and low latitude warming. |
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