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| Titel |
Constraining Climate Sensitivity using Top Of Atmosphere Radiation Measurements. |
| VerfasserIn |
Simon Tett, Michael Mineter, Coralia Cartis, Dan Rowlands, Ping Liu |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250050040
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| Zusammenfassung |
| Considerable uncertainty still exists about the equilibrium sensitivity of the climate system
to external forcings with the most recent report of the IPCC estimating a likely
range of 2.0 to 4.5K with a best estimate of 3K. Though the IPCC did not rule out
climate sensitivities greater than 4.5K. These uncertainties lead to considerable
uncertainty in the possible response of the climate system to changes in greenhouse
gases. Uncertainty in climate sensitivity largely arises from uncertainty in modelling
processes such as cloud formation, convection and rainfall in the atmosphere as
well as changes in snow and ice which act to modify the “greenhouse” effect and
albedo of the planet. Analysis of observed change has, so far, failed to produce tight
constraints on climate sensitivity. One recent fruitful area of analysis is perturbed physics
ensembles. In these key parameters in a climate model are varied within their uncertainty
ranges and the response of this ensemble to changes in CO2 explored leading to
the possibility of very high climate sensitivities. Here we show that requiring the
perturbed physics configurations of the HadAM3 model to be consistent, at a p-value of
99% or better, with recent Top Of Atmosphere Reflected Shortwave Radiation and
Outgoing Longwave Radiation observations and in near radiative balance gives
climate sensitivities in the range 2.7 to 3.8K. Comparison of a set of similar, though
not identical, AMIP-style atmospheric models simulations carried out for the 3rd
assessment report with the same radiation observations suggests that only models with a
climate sensitivity of 2.7 to 4.4K are consistent with observations at a p-value of
99% and that many of these models are inconsistent with satellite observations of
top of atmosphere radiation. Therefore, our results suggest that low or very high
climate sensitivities can be ruled out on the basis of recent satellite measurements. |
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