Abrupt global warming can cause a shift in monsoon patternsJune 12th, 2009 - 1:27 pm ICT by ANI
Washington, June 12 (ANI): A new study has determined that an abrupt change in climate, like global warming, can cause a shift in monsoon patterns and hurt agriculture.
The study took into account the fact that an abrupt change in climate in the distant past has been associated with a shift of seasonal monsoons to the south, 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.
“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,” he added.
The findings were based on oxygen isotopes in air from ice cores, and supported by previously published data from ancient stalagmites found in caves.
The researchers used oxygen measurements, as recorded in air bubbles in ice cores from Antarctica and Greenland, to gauge the changes taking place in vegetation during the past 100,000 years.
Increases or decreases in vegetation growth can be determined by measuring the ratio of two different oxygen isotopes in air.
They were also able to verify and confirm these measurements with data from studies of ancient stalagmites on the floors of caves in China, which can reveal rainfall levels over hundreds of thousands of years.
“Both the ice core data and the stalagmites in the caves gave us the same signal, of very dry conditions over broad areas at the same time,” Brook said.
“We believe the mechanism causing this was a shift in monsoon patterns, more rain falling over the ocean instead of the land. That resulted in much lower vegetation growth in the regions affected by these monsoons, in what is now India, Southeast Asia and parts of North Africa,” he added.
Previous research has determined that the climate can shift quite rapidly in some cases, in periods as short as decades or less.
This study provides a barometer of how those climate changes can affect the Earth’s capacity to grow vegetation. (ANI)
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Tags: 100 000 years, abrupt change, abrupt climate change, abrupt global warming, agricultural production, air bubbles, climate models, core data, dramatic drop, geosciences, global vegetation, ice cores, monsoons, osu professor, oxygen isotopes, precise data, rainfall levels, stalagmites, tropical regions, vegetation growth