Amazon droughts release huge amounts of CO2

A new study for the journal Science has shown that the Amazon suffered a second serious drought last year, making it two severe droughts within 5 years.

While normally the Amazon rainforest absorbs huge amounts of CO2, droughts cause the reverse effect, with the forests releasing emissions.

The drought last year may exceed the 5 billion tonnes of CO2 that the last drought in 2005 caused. This is roughly equal to the annual emissions of the US.

Lead author Dr Simon Lewis, from the University of Leeds, said: “Having two events of this magnitude in such close succession is extremely unusual, but is unfortunately consistent with those climate models that project a grim future for Amazonia.”

The drought is particularly worrying as it would normally be a ‘once in a century’ event. In addition to the effects on CO2, the drought has devastated wildlife and trees in the area.

Co-author Dr Paulo Brando, from Brazil’s Amazon Environmental Research Institute (IPAM), said: “We will not know exactly how many trees were killed until we can complete forest measurements on the ground.

“It could be that many of the drought susceptible trees were killed off in 2005, which would reduce the number killed last year. On the other hand, the first drought may have weakened a large number of trees so increasing the number dying in the 2010 dry season.

“Our results should be seen as an initial estimate. The emissions estimates do not include those from forest fires, which spread over extensive areas of the Amazon during hot and dry years. These fires release large amounts of carbon to the atmosphere.”

While more research is needed to understand the causes of the droughts and how this may be linked to climate change, the concern is that the Amazon may become a major producer of CO2 rather than absorbing it.

Alison Brown

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