Changes in South Pacific rainfall bands in a warming climate

Matthew Widlansky, Axel Timmermann, Karl Stein, Shayne McGregor, Niklas Schneider, Matthew Heathcote England, Matthieu Lengaigne, Wenju Cai

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55 Citations (Scopus)


The South Pacific Convergence Zone (SPCZ) is the largest rainband in the Southern Hemisphere and provides most of the rainfall to southwest Pacific island nations. In spite of various modelling efforts, it remains uncertain how the SPCZ will respond to greenhouse warming. Using a hierarchy of climate models we show that the uncertainty of SPCZ rainfall projections in present-generation climate models can be explained as a result of two competing mechanisms. Higher tropical sea surface temperatures lead to an overall increase of atmospheric moisture and rainfall whereas weaker sea surface temperature gradients dynamically shift the SPCZ northeastward and promote summer drying in areas of the southwest Pacific. On the basis of a multi-model ensemble of 76 greenhouse warming experiments and for moderate tropical warming of 1-2C we estimate a 6 decrease of SPCZ rainfall with a multi-model uncertainty exceeding 20 . For stronger tropical warming exceeding 3C, a tendency for a wetter SPCZ region is identified. (c) 2013 Macmillan Publishers Limited. All rights reserved.
Original languageEnglish
Pages (from-to)417 - 423
Number of pages7
JournalNature Climate Change
Issue number4
Publication statusPublished - 2013
Externally publishedYes

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