WASHINGTON – There’s no other way to put it: Cutting down tropical forests is disastrous. The lush plant life in these areas sequesters huge amounts of carbon, pulling it out of the atmosphere to fuel plant growth. Chopping down a rain forest releases carbon back to the atmosphere, worsening global warming.
But at least this problem was supposed to be getting better – a little.
According to the United Nations Intergovernmental Panel on Climate Change, recent years have seen “decreasing deforestation rates and increased afforestation” – and, thus, less carbon dioxide pouring into the atmosphere from this source. Similarly, a 2010 report from the UN Food and Agriculture Organization found that while 16 million hectares of forest per year were lost in the 1990s, only 13 million per year were lost in the 2000s.
But according to a new study in the journal Geophysical Research Letters, the U.N. has it wrong. The study, by University of Maryland geographer Do-Hyung Kim and two colleagues, uses satellite imagery to examine how tropical forests in particular are faring. And their answer is far from heartening.
“Our estimates indicate a 62% acceleration in net deforestation in the humid tropics from the 1990s to the 2000s,” the authors write.
The new study looked at the tropical forests of 34 countries, including Brazil, Indonesia and Thailand, that collectively house 80 percent of the world’s tropical forest area. Brazil “dominated” tropical forest losses, showing a 33 percent acceleration in the amount of forest that was lost, the study said.
So why the big difference with the UN estimates? According to Kim, it’s because his research uses a fixed satellite algorithm to estimate the extent of forest cover over time, whereas the UN “mostly uses country-based self-reports.”
“We developed a fully automated method to map the forests and non-forests,” Kim said. “We can enforce a consistent definition and method through space and time.”
The new study did find that in the second half of the 2000s, tropical deforestation showed a “small deceleration,” as losses slowed in Brazil even as the Asian tropics saw an increased rate of reforestation.
One of the chief drivers of deforestation is the conversion of forest land into land for agricultural purposes. But the causes vary in different parts of the world, according to Kim.
The reason the rate of deforestation increased, he suggested, may be because people were able to use more powerful industrial technologies to clear forests more quickly.
The loss of Amazon rain forest may be coming back to bite Brazil right now. The country is suffering from a devastating drought, which is threatening water supplies to the megacity of São Paulo. Researchers have blamed the drought conditions, in part, on deforestation.
