Changing climate pushed islanders to ’chase the rain’ across the Pacific 1,000 years ago

Credit: coastalandoffshorecruising.com

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In case anyone still thinks ‘climate change’ was invented when coal became an industrial fuel, think again. Natural variation has always been around, and always will be. The causes are not identified here, except to point to ‘a natural change in the pattern of sea surface temperatures across the Pacific’.
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Research by the University of Southampton and University of East Anglia (UEA) shows a major shift in South Pacific climate conditions—beginning around 1,000 years ago—that may have pushed people to settle further east and move away from increasingly drier conditions in the west.

Settled islands in Western Polynesia, such as Samoa and Tonga, became drier, while more remote ones in Eastern Polynesia, for example French Polynesia (Tahiti), gradually became wetter and more attractive for colonisation.

This latest study, part of a wider project between Southampton and UEA called PROMS (Pacific Rainfall over Millennial Timescales), examines this shift and its likely impact on migration.

Findings are published in the journal Nature: Communications Earth and Environment .

Principal Investigator for PROMS, Professor David Sear comments: “The Pacific Islands today are under threat from changing climate, but we can see from our research that this is not the first time the inhabitants of the region have had to adapt to a changing climate.

“Our research suggests that beginning around 1,000 years ago, people in the region were effectively chasing the rain eastwards as part of adapting to the stress placed on growing populations by a period of drier conditions developing in the western South Pacific.”
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The most likely cause is that a natural change in the pattern of sea surface temperatures across the Pacific drove an eastward shift of the South Pacific Convergence Zone (SPCZ) between approximately 1,100 and 400 years ago.

The SPCZ is one of the biggest features in the global climate system, a region of high rainfall stretching over 7,000 km from Papua New Guinea to beyond the Cook Islands. The climate shift identified in this new study saw the western part of this rain band become progressively drier, and its eastern part wetter.
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Co-Principal Investigator Professor Manoj Joshi, from UEA, says: “By better understanding how the climate of the South Pacific has been affected by larger-scale climate changes over past millennia, we can build better predictions for how future climate change will affect the region.”

Full article here.
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Image credit: coastalandoffshorecruising.com