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| Titel |
Rhythm and theoretical perception of climate change during the 21st century using CMIP5 simulations |
| VerfasserIn |
Yann Chavaillaz, Sylvie Joussaume, Pascale Braconnot, Robert Vautard |
| 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 |
250088525
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| Publikation (Nr.) |
 EGU/EGU2014-2636.pdf |
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| Zusammenfassung |
| In most studies, climate change is approached by focusing on the evolution between a fixed
current baseline and future, emphasizing stronger warming as we move further from the
current climate. This long-term vision is used in order to characterize quantitatively the
magnitude and expected effects of mitigation policies across the globe. In this study, an
alternative approach more focused on adaptation is envisaged. It considers the rhythm of
climate change by following it up with a running baseline over periods of 20 years, defining
the time evolution of the speed at which climate changes. Comparing this speed with the
variability of the previous 20 years, our work also aims to give an idea on how
fast the climate changes from the recent year-to-year variability. This represents
a theoretical approach of perception of climate change, as a 20-year period can
illustrate the memory of a generation. In this way, we also evaluate how much adapting
to the recent past 20 years is sufficient to cope with the expected changes of the
coming ones. As a result, we estimate the stress on adaptation needs over the 21st
century.
Here we are mainly interested on mean and variability of surface air temperature and
precipitations. A multi-model study based on CMIP5 RCP8.5 scenario is conducted.
Over the 21st century, important changes occur in terms of surface air temperature. These are
mainly characterized by an increase of warming speed resulting in its doubling at the end of
the century (2071-2090) compared to the IPCC current baseline (1986-2005), although
models exhibit a different climate sensitivity. Despite an unanimous stronger speed in high
latitudes of the Northern Hemisphere than anywhere else, the speed can increase more rapidly
in some other regions.
When comparing the warming speed with year-to-year variability, the change of surface air
temperature appears to be perceived stronger and sooner in tropical areas than in any other
regions, especially in South-East Asia. By the end of the century, 50 to 70 percents of these
areas have a mean temperature out of the 2Ïă-limit given by the distribution of the previous 20
years.
Consistently with temperature, regions which are drying (moistening) tend to experience an
increase in drying (moistening) speed. Drying regions being fewer than moistening ones and
drying speed being weaker than moistening one, a continuous intensification of the
hydrological cycle is confirmed. Besides, their spatial fraction over the globe appears to
remain unchanged (about 65% of regions are moistening), and also stabilizes in the second
half of the century in their geographical distribution. |
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