Taylor, CM, Belušić, D, Guichard, F et al. (7 more authors) (2017) Frequency of extreme Sahelian storms tripled since 1982 in satellite observations. Nature, 544 (7651). pp. 475-478. ISSN 0028-0836
Abstract
The hydrological cycle is expected to intensify under global warming¹, with studies reporting more frequent extreme rain events in many regions of the world²³⁴, and predicting increases in future flood frequency⁵. Such early, predominantly mid-latitude observations are essential because of shortcomings within climate models in their depiction of convective rainfall⁶⁷. A globally important group of intense storms—mesoscale convective systems (MCSs)⁸—poses a particular challenge, because they organize dynamically on spatial scales that cannot be resolved by conventional climate models. Here, we use 35 years of satellite observations from the West African Sahel to reveal a persistent increase in the frequency of the most intense MCSs. Sahelian storms are some of the most powerful on the planet⁹, and rain gauges in this region have recorded a rise in ‘extreme’¹⁷ daily rainfall totals. We find that intense MCS frequency is only weakly related to the multidecadal recovery of Sahel annual rainfall, but is highly correlated with global land temperatures. Analysis of trends across Africa reveals that MCS intensification is limited to a narrow band south of the Sahara desert. During this period, wet-season Sahelian temperatures have not risen, ruling out the possibility that rainfall has intensified in response to locally warmer conditions. On the other hand, the meridional temperature gradient spanning the Sahel has increased in recent decades, consistent with anthropogenic forcing driving enhanced Saharan warming¹⁰. We argue that Saharan warming intensifies convection within Sahelian MCSs through increased wind shear and changes to the Saharan air layer. The meridional gradient is projected to strengthen throughout the twenty-first century, suggesting that the Sahel will experience particularly marked increases in extreme rain. The remarkably rapid intensification of Sahelian MCSs since the 1980s sheds new light on the response of organized tropical convection to global warming, and challenges conventional projections made by general circulation models.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2017 Macmillan Publishers Limited, part of Springer Nature. This is an author produced version of a paper published in Nature. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Hydrology; Atmospheric science |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst for Climate & Atmos Science (ICAS) (Leeds) |
Funding Information: | Funder Grant number Royal Society No External Reference EU - European Union EXT GOCE 004089 NERC NE/B505538/1 EU - European Union GOCE 004089 NERC NE/G018499/1 NERC NE/M020126/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 02 May 2017 09:32 |
Last Modified: | 06 Oct 2020 12:30 |
Published Version: | https://doi.org/10.1038/nature22069 |
Status: | Published |
Publisher: | Nature Publishing Group |
Identification Number: | 10.1038/nature22069 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:115325 |