Large areas of the Amazon rainforest appear to be deteriorating as a result of drought due to climate change, new research from Nasa reveals.
An area of the Amazon rainforest twice the size of California has suffered from a megadrought that began in 2005, causing widespread changes to the forest canopy that were detectable by satellite.
While rainfall levels picked up post 2005, the old-growth forest in southwestern Amazonia appears to have struggled to recover before another drought hit the area in 2010.
Scientists say the changes suggest dieback of branches and tree falls, especially among the older, larger, more vulnerable canopy trees that blanket the forest.
Left: the extent of the 2005 megadrought in the western Amazon rainforests during the summer months of June, July and August. The most impacted areas are shown in shades of red and yellow. The circled area in the right panel shows the forest areas that experienced slow recovery from the 2005 drought, with areas in red and yellow shades experiencing the slowest recovery. Image credit: NASA/JPL-Caltech/GSFC
According to Nasa, the drought rate in Amazonia during the past decade is unprecedented over the past century.
In addition to the two major droughts in 2005 and 2010, the area has experienced several localized mini-droughts in recent years.
Observations from ground stations show that rainfall over the southern Amazon rainforest declined by almost 3.2% per year in the period from 1970 to 1998.
“Our results suggest that if droughts continue at five to 10-year intervals or increase in frequency due to climate change, large areas of the Amazon forest are likely to be exposed to persistent effects of droughts and corresponding slow forest recovery,” Nasa study leader Sassan Saatchi said.
“This may alter the structure and function of Amazonian rainforest ecosystems.”
The area is also of huge economic importance to Brazil, which critically relies on the Amazon region to provide a regular flow of water for its hydropower stations.
The Amazon rainforest plays a vital role in the global ecosystem, regulating temperatures, storing vast quantities of carbon dioxide, as well as providing a home to a huge variety of plants and animals.
In recent years rates of deforestation have slowed, although the total area of rainforest is still shrinking.