A new study suggests the Amazon rainforest could be dying faster than we thought, taking with it one of the highest concentrations of biodiversity on Earth and releasing a massive amount of carbon dioxide into the atmosphere.
After studying rainfall measurements from the past 30 years researchers found the Amazon's "dry season" has gotten about a week longer every decade since 1979, a University of Texas Jackson School of Geosciences news release reported. The annual fire season has lengthened as well, and scientists are blaming climate change.
"The dry season over the southern Amazon is already marginal for maintaining rainforest," study leader Rong Fu, professor at The University of Texas at Austin's Jackson School of Geosciences, said. "At some point, if it becomes too long, the rainforest will reach a tipping point."
The Amazon rainforest usually removes greenhouse gases from the atmosphere, but during a 2005 drought it actually released carbon dioxide. If things continue as they are, similar events could be considered the norm by the end of the century.
These new findings contradict predictions recently released by the Intergovernmental Panel on Climate Change (IPCC), which believe at the end of the century the Amazon's dry season will only be "a few to 10 days longer" which would leave the region with a relatively low risk of global warming-related devastation.
"The length of the dry season in the southern Amazon is the most important climate condition controlling the rainforest," Fu, said. "If the dry season is too long, the rainforest will not survive."
No matter how long the wet season is the rainforest's soil can only hold so much water at once, if the dry season is too long there me not be enough moisture to last through the drought.
The team believes the longer dry spells are a result of manmade greenhouse gases, which have been known to suppress rainfall. The gases make it "harder for warm, dry air near the surface to rise and freely mix with cool, moist air above." The pollution also blocks cold fronts that could trigger rainstorms.
"Because of the potential impact on the global carbon cycle, we need to better understand the changes of the dry season over southern Amazonia," Fu said.
