Paul Smith's Prof Links Climate Change, Drought in Southern Hemisphere

Drought-Sensitive Regions Most Vulnerable to Warming, Researchers Say

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Jay White (left) and Christiaan King (center) of Paul Smith's College help carry a sediment core ashore from Lake Verlorenvlei in South Africa. The core dates back 1,400 years.

PAUL SMITHS, NY (05/15/2012)(readMedia)-- Warming climate may mean less rainfall for drought-sensitive regions of the Southern Hemisphere, according to a study published by a professor at Paul Smith's College and an international team of researchers and students.

As part of the study, which was supported by the National Science Foundation, Curt Stager and colleagues found that rainfall in South Africa over the last 1,400 years was affected by temperature – with more rain falling during cool periods and less during warm ones.

The work was recently published in the online journal Climate of the Past.

"Climate models have been showing that global warming could push storm tracks southwards and away from the mainlands of southern Africa, South America and Australia," said Stager. "This research supports those predictions of increasing aridity, which could lead to major problems for societies and unique ecosystems in those already-arid places."

Stager, who was lead author of the study, collected sediment samples from Lake Verlorenvlei, in South Africa. By analyzing tiny, glassy-shelled algae that were preserved in sediment layers brought from the bottom of the lake, he and the researchers were able to reconstruct rainfall patterns dating back to 600 A.D.

Two Paul Smith's College undergraduate students, Christiaan King and Jay White, also participated in the study, along with scientists from the University of Maine and institutions in South Africa and Europe.

Rainfall at the southernmost tip of Africa is governed by a belt of eastward-trending winds that migrate like a meandering river depending on the season. In summer months, those winds drift closer to Antarctica, carrying rain clouds over the ocean; in winter, they move over the continent. The shifting winds bring rains that provide much of the nation's annual water supply.

Tellingly, the research showed a dramatic increase of rainfall at Verlorenvlei during a natural cooling period during the 14th to 19th centuries. The link between temperature and rainfall is also expected to hold in reverse, if global warming continues.

"A poleward retreat of these winds would have serious consequences for cities like Cape Town, for farms and wineries, and for animal and plant communities," Stager said. "The same also appears to be true for the winter rainfall regions of South America and Australia-New Zealand."

Co-author Michael Meadows, with the University of Cape Town, said that hundreds of species of rare native plants could be affected by the changes. "These dry-land plants are tough," he said. "But further aridity could make fires more frequent as well, which could make it even harder on the plants and possibly threaten their very existence."

Stager said regions associated with these mobile storm tracks are exceptionally vulnerable to the effects of greenhouse gas buildups, though this is not yet widely recognized. "When it comes to climate change, there's more to consider than warming alone. In places like these, increasing drought could bring great challenges as well."

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