Large areas of Earth drying up: study

Mainly due to climate change, large swaths of Earth have been drying up, posing a threat to the ecosystem, a new study revealed.

The drying areas are mainly in the Southern Hemisphere, including large parts of Australia, Africa and South America, according to the study conducted by researchers at Oregon State University.

In large portions of the world, soils are now becoming drier than they used to be, releasing less water and offsetting some moisture increases elsewhere, said the study published in the issue of the journal Nature.

The study is the first major one of its kind to look at the movement of water from the land to the atmosphere, called 'evapotranspiration,' on a global scale.

Most climate models have suggested that evapotranspiration would increase with global warming, because of increased evaporation of water from the ocean and more precipitation overall (water that can evaporate).

Because the data only goes back for a few decades, the researchers say they can't be certain whether the change is part of the natural variability of climate or part of a longer-lasting global change.

One possibility, though, is that on a global level, a limit to the acceleration of the hydrological cycle (the transfer of water between land, air and sea) on land has already been reached. If that's the case, the consequences could be serious.

They could include reduced terrestrial vegetation growth, less carbon absorption, a loss of the natural cooling mechanism provided by evapotranspiration, more heating of the land surface, more intense heat waves and a 'feedback loop' that could intensify global warming, the study said.

"We didn't expect to see this shift in evapotranspiration over such a large area of the Southern Hemisphere," said study co- author Beverly Law, a professor of global change forest science.

"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."

Meanwhile, more thorough sea level monitoring is needed to protect one trillion dollars (0.98 trillion U.S. dollars) worth of the world's infrastructure threatened by climate change, an Australian leading ocean scientist said.

In the book 'Understanding Sea-level Rise and Variability,' released recently, Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO) oceanographer John Church said the best way to predict the impacts of climate change is to look at the sea.

"The oceans are absolutely central to climate change," Church told Australia Associated Press.

"If we want to predict climate change accurately we've got to look at the oceans and for that matter the ice sheets."

Dr Church said there are around one trillion dollars (0.98 trillion U.S. dollars) worth of infrastructure, and 140 million people living a metre or less above sea-level, and therefore, the sea-level data is very important.

"These coastal areas - the infrastructure and the environment - are already affected by extreme events," Dr Church said.

"With no significant greenhouse gas mitigation to date, it's becoming increasingly clear that we need to adapt to rising sea levels." - Xinhua