This year an important Amazon river tributary, the Rio Negro, fell to its lowest ever recorded level. Droughts are likely to occur more frequently and become more intense in the future due to climate change. Image: Rodrigo Baléia / Greenpeace

Severe drought could turn the Amazon rainforest into a source of carbon emissions contributing to climate change, rather than a carbon sink absorbing emissions. This is one of the alarming findings of a new study featured in Science, which has found that drought has again damaged the world’s largest rainforest. Unfortunately severe droughts like the one that occurred last year, and previously in 2005, fit the predictions of the climate change impacts we can expect for the Amazon. As climate change takes hold, we may see more extreme weather and more damaging droughts in the Amazon region, but we can also act to boost the resilience of the rainforest to these events.

The key to increasing the strength of forests to withstand drought and other climate impacts is to maintain and protect intact areas of forest. This means stopping deforestation, which makes the impacts of drought worse. Numerous studies show that deforestation chops forest into smaller and smaller fragments, and the edges of these fragments are drier than the interiors. The more fragmentation there is, the more dry edges there are and therefore the forest becomes even more vulnerable to drought and fire. Drought and fire then further fragment the forest, increasing its vulnerability even further – in a vicious cycle that weakens the forests ability to withstand the impacts of climate change.

It doesn’t stop there. Severe drought and resulting fires release carbon previously stored by the forest, thereby fuelling change. And the loss of forest makes the Amazon less effective in soaking up carbon from the atmosphere, a crucial role that forests play in slowing climate change. The impacts of climate change – such as severe drought – combined with deforestation threaten to transform the Amazon rainforest from a valuable asset in the fight to stop climate change - into a source of emissions that speed it up. Stopping deforestation will help to protect the Amazon and ensure it remains a valuable carbon sink that will help us mitigate the consequences of climate change.

Scientists agree that large continuous areas of intact forest are more resistant to climate change than small areas of degraded forests. They have more moisture to withstand extreme drought, and also act as better buffers against other climate impacts like severe storms. And, of course protecting the Amazon is also crucial to protecting biodiversity, since intact forest is also important for animals - especially for large mammals that need extensive areas to forage or hunt - and aids in the migration of species.

Roughly 80% of the Amazon forest remains intact. The alarming findings of this latest study only make it more clear how vital it is for us to protect this intact rainforest from deforestation and lessen the climate impacts, like severe droughts, that damage forests by reducing carbon emissions contributing to climate change.

[The report 'The 2010 Amazon Drought' in Science magazine: Lewis, S.L., Brando, P.M.,  Phillips, O.L. van der Heijden, G.M.F. &  Nepstad, D. 2011. The 2010 Amazon Drought. Science 331: 554.]