Deforestation Effects Tropical Rainfall: Study

A team of researchers from the University of Leeds and the NERC Centre for Ecology & Hydrology have come up with a startling study that states destruction of tropical forest would reduce rain across the Amazon basin by 21 percent by 2050.

According to the study that is carried in Nature, the findings have potentially devastating impact on the people living in and near the Amazon and Congo forest. The researchers found that that for the majority of Earth's tropical land surface, air passing over extensive forests produces at least twice as much rain as air passing over little vegetation. In some cases these forests increased rainfall thousands of kilometres away.

Lead author Dr Dominick Spracklen from the School of Earth and Environment at the University of Leeds said: "We were surprised to find that this effect occurs strongly across more than half of the tropics. We found that the Amazon and Congo forests maintain rainfall over the periphery of the forest basins -- regions where large numbers of people live and rely on rainfall for their livelihoods.

"Our study implies that deforestation of the Amazon and Congo forests could have catastrophic consequences for the people living thousands of kilometres away in surrounding countries."

Whether, vegetation increase rainfall had been a topic of debate for several years. But it is established that the process of evapotranspiration retains moisture back in air. But the scientists failed to get an idea on the quantity and geographical reach of rainfall generated by large forests.

The team worked on the data that was provided by NASA's satellite observations of rainfall and vegetation along with a model that predicts atmospheric wind flow patterns to study the impact of Earth's tropical forest.

"We looked at what had been happening to the air over previous days -- where it came from and how much forest it had travelled over," Dr Spracklen said.

The journey of air masses arriving over different parts of the forest was studied to get a more insight. The researchers learnt that   the more vegetation the air had travelled over, the more moisture it carried and more rain was produced.

Dr Stephen Arnold from the University of Leeds, a co-author on the paper, said: "The observations show that to understand how forests impact rainfall, we need to account for how air has interacted with vegetation during its journey through the atmosphere often over thousands of kilometres. This has significant implications for how policy makers should consider the environmental impacts of deforestation, since its effects on rainfall patterns may be felt not only locally, but on a continental scale."

Dr Spracklen said, "The findings showed the importance of initiatives to protect tropical forests."

 "Brazil has recently made progress in slowing the historically high rates of deforestation across the Amazon and our study emphasises that this progress must be maintained if impacts on rainfall are to be avoided.

"The Amazon forest maintains rainfall over important agricultural regions of Southern Brazil, while preserving the forests of the Congo Basin increases rainfall in regions of Southern Africa where rainfed agriculture is important. Increased drought in these regions would have severe implications for their mostly subsistence farmers."

A team of researchers from the University of Leeds and the NERC Centre for Ecology & Hydrology have come up with a startling study that states destruction of tropical forest would reduce rain across the Amazon basin by 21 percent by 2050.

According tot the study that is carried in Nature, says the findings have potentially devastating impact on the people living in and near the Amazon and Congo forest. The researchers found that that for the majority of Earth's tropical land surface, air passing over extensive forests produces at least twice as much rain as air passing over little vegetation. In some cases these forests increased rainfall thousands of kilometres away.

Lead author Dr Dominick Spracklen from the School of Earth and Environment at the University of Leeds said: "We were surprised to find that this effect occurs strongly across more than half of the tropics. We found that the Amazon and Congo forests maintain rainfall over the periphery of the forest basins -- regions where large numbers of people live and rely on rainfall for their livelihoods.

"Our study implies that deforestation of the Amazon and Congo forests could have catastrophic consequences for the people living thousands of kilometres away in surrounding countries."

Whether, vegetation increase rainfall had been a topic of debate for several years. But it is established that the process of evapotranspiration retains moisture back in air. But the scientists failed to get an idea on the quantity and geographical reach of rainfall generated by large forests.

The team worked on the data that was provided by NASA's satellite observations of rainfall and vegetation along with a model that predicts atmospheric wind flow patterns to study the impact of Earth's tropical forest.

"We looked at what had been happening to the air over previous days -- where it came from and how much forest it had travelled over," Dr Spracklen said.

The journey of air masses arriving over different parts of the forest was studied to get a more insight. The researchers learnt that   the more vegetation the air had travelled over, the more moisture it carried and more rain was produced.

Dr Stephen Arnold from the University of Leeds, a co-author on the paper, said: "The observations show that to understand how forests impact rainfall, we need to account for how air has interacted with vegetation during its journey through the atmosphere often over thousands of kilometres. This has significant implications for how policy makers should consider the environmental impacts of deforestation, since its effects on rainfall patterns may be felt not only locally, but on a continental scale."

Dr Spracklen said, "The findings showed the importance of initiatives to protect tropical forests."

 "Brazil has recently made progress in slowing the historically high rates of deforestation across the Amazon and our study emphasises that this progress must be maintained if impacts on rainfall are to be avoided.

"The Amazon forest maintains rainfall over important agricultural regions of Southern Brazil, while preserving the forests of the Congo Basin increases rainfall in regions of Southern Africa where rainfed agriculture is important. Increased drought in these regions would have severe implications for their mostly subsistence farmers."