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| Titel |
Elusive drought: uncertainty in observed trends and short- and long-term CMIP5 projections |
| VerfasserIn |
B. Orlowsky, S. I. Seneviratne |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 17, no. 5 ; Nr. 17, no. 5 (2013-05-07), S.1765-1781 |
| Datensatznummer |
250018870
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| Publikation (Nr.) |
 copernicus.org/hess-17-1765-2013.pdf |
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| Zusammenfassung |
| Recent years have seen a number of severe droughts in different
regions around the world, causing agricultural and economic losses,
famines and migration. Despite their devastating consequences, the
Standardised Precipitation Index (SPI) of these events lies within
the general range of observation-based SPI time series and
simulations from the 5th phase of the Coupled Model Intercomparison
Project (CMIP5). In terms of magnitude, regional trends of SPI over
the last decades remain mostly inconclusive in observation-based
datasets and CMIP5 simulations, but Soil Moisture Anomalies (SMAs)
in CMIP5 simulations hint at increased drought in a few regions
(e.g., the Mediterranean, Central America/Mexico, the Amazon,
North-East Brazil and South Africa). Also for the future,
projections of changes in the magnitude of meteorological (SPI) and
soil moisture (SMA) drought in CMIP5 display large spreads over all
time frames, generally impeding trend detection. However,
projections of changes in the frequencies of future drought events
display more robust signal-to-noise ratios, with detectable trends
towards more frequent drought before the end of the 21st century in
the Mediterranean, South Africa and Central America/Mexico. Other
present-day hot spots are projected to become less drought-prone, or
display non-significant changes in drought occurrence. A separation
of different sources of uncertainty in projections of meteorological
and soil moisture drought reveals that for the near term, internal
climate variability is the dominant source, while the formulation of
Global Climate Models (GCMs) generally becomes the dominant source
of spread by the end of the 21st century, especially for soil
moisture drought. In comparison, the uncertainty from Green-House Gas
(GHG) concentrations scenarios is negligible for most regions.
These findings stand in contrast to respective analyses for a heat
wave index, for which GHG concentrations scenarios constitute the
main source of uncertainty. Our results highlight the inherent
difficulty of drought quantification and the considerable likelihood
range of drought projections, but also indicate regions where
drought is consistently found to increase. In other regions, wide
likelihood range should not be equated with low drought risk, since
potential scenarios include large drought increases in key
agricultural and ecosystem regions. |
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