CORVALLIS, Ore., Oct. 11 (UPI) — Large parts of the Southern Hemisphere have been drying up in the last 10 years, a possible sign of global change, U.S. scientists say.
The first major study to examine “evapotranspiration” — the movement of water from land to the atmosphere — on a global basis, shows that in the late 1990s it slowed dramatically or even stopped in some parts of the world, an Oregon State University release said Monday.
Scientists say they can’t be sure whether this is a natural variability or part of a longer-lasting global change, but suspect a limit to the hydrological cycle on land has may have been reached.
The consequences could be serious, they say, including less terrestrial vegetation growth, reduced carbon absorption, and more heating of the land surface with more intense heat waves that could intensify global warming.
“This is the first time we’ve ever been able to compile observations such as this for a global analysis,” Beverly Law, a professor of global change forest science at OSU, said.
“We didn’t expect to see this shift in evapotranspiration over such a large area of the Southern Hemisphere,” Law said. “It is critical to continue such long-term observations, because until we monitor this for a longer period of time, we can’t be sure why this is occurring.”
Southeast Africa, much of Australia, central India, large parts of South America and some of Indonesia are affected. While many of those regions are historically dry, some also contain tropical rainforests.
About 60 percent of annual precipitation is returned to the atmosphere by evapotranspiration, a key component of the global climate system.
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