The Amazon forest stores about half of the global tropical forest carbon and accounts for about a quarter of carbon absorption from the atmosphere by global forests each year. As a result, large losses of Amazonian forest cover could make global climate change worse.
In the past, researchers have found that a large part of the Amazon forest is susceptible to a tipping point. The tell-tail sign is satellite data showing areas of savannah and rainforest coexisting under the same environmental conditions. Theories from nonlinear dynamics would then suggest that both states are alternative stable outcomes. This so called bistability means that shocks such as forest clearance or drought could lead to a dramatic increase of fire occurrence and tip an area of rainforest into savannah. Areas that have experienced this transition would then remain locked into this savannah state until large enough increases of rainfall and release of human pressures allow forests to regrow faster than they are lost by intermittent fires.
The Amazon forest stores about half of the global tropical forest carbon and accounts for about a quarter of carbon absorption from the atmosphere by global forests each year. As a result, large losses of Amazonian forest cover could make global climate change worse.
In the past, researchers have found that a large part of the Amazon forest is susceptible to a tipping point. The tell-tail sign is satellite data showing areas of savannah and rainforest coexisting under the same environmental conditions. Theories from nonlinear dynamics would then suggest that both states are alternative stable outcomes. This so called bistability means that shocks such as forest clearance or drought could lead to a dramatic increase of fire occurrence and tip an area of rainforest into savannah. Areas that have experienced this transition would then remain locked into this savannah state until large enough increases of rainfall and release of human pressures allow forests to regrow faster than they are lost by intermittent fires.
Bert Wuyts, a fourth year PhD student in the Bristol Centre for Complexity Sciences and lead author on the paper, said: “I decided to take a fresh look at the data and a very different picture emerged when I controlled for seasonality and took out all the data points from satellite images that represented locations that had been subjected to human influence. Suddenly the property of bistability disappeared almost completely.”
Bert, who made this discovery in the first year of his PhD, thought it seemed most puzzling, so he teamed up with Professor Alan Champneys, a theorist in the Department of Engineering Mathematics, and Dr Jo House, an expert on land use change from the School of Geographical Sciences. For the past two years they have been examining these findings rigorously.
Continue reading at University of Bristol
Image via University of Bristol
