Changes in South Pacific rainfall bands in a warming climate
Author: ["Matthew J. Widlansky","Axel Timmermann","Karl Stein","Shayne McGregor","Niklas Schneider","Matthew H. England","Matthieu Lengaigne","Wenju Cai"]
Publication: Nature Climate Change
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Abstract
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 1–2 °C we estimate a 6% decrease of SPCZ rainfall with a multi-model uncertainty exceeding ±20%. For stronger tropical warming exceeding 3 °C, a tendency for a wetter SPCZ region is identified. The South Pacific Convergence Zone is the largest rainband in the Southern Hemisphere, and its response to global warming is still undetermined. In this study a hierarchy of climate models show that the uncertainty in rainfall projections in the South Pacific Convergence Zone is the result of two competing mechanisms.
Cite this article
Widlansky, M., Timmermann, A., Stein, K. et al. Changes in South Pacific rainfall bands in a warming climate. Nature Clim Change 3, 417–423 (2013). https://doi.org/10.1038/nclimate1726
