Abrupt global warming could shift monsoon patterns, hurt agriculture

Science Daily: At times in the distant past, an abrupt change in climate has been associated with a shift of seasonal monsoons to the south, a new study concludes, causing more rain to fall over the oceans than in the Earth's tropical regions, and leading to a dramatic drop in global vegetation growth.

If similar changes were to happen to the Earth's climate today as a result of global warming – as scientists believe is possible - this might lead to drier tropics, more wildfires and declines in agricultural production in some of the world's most heavily populated regions.

The findings were based on oxygen isotopes in air from ice cores, and supported by previously published data from ancient stalagmites found in caves. They will be published Friday in the journal Science by researchers from Oregon State University, the Scripps Institution of Oceanography and the Desert Research Institute in Nevada. The research was supported by the National Science Foundation.

The data confirming these effects were unusually compelling, researchers said. "Changes of this type have been theorized in climate models, but we've never before had detailed and precise data showing such a widespread impact of abrupt climate change," said Ed Brook, an OSU professor of geosciences. "We didn't really expect to find such large, fast environmental changes recorded by the whole atmosphere. The data are pretty hard to ignore."….

Drawing of an astrolabe, from Geschichte der Astron. Messwerkzeuge, 1907, J.A.Repsold † 1919