Study warns that the rainforest’s ability to absorb greenhouse gases could be reduced by the drying process (Image: Nasa)

The Amazon rainforest is drying out and it could increase the risk of catastrophic wildfires.

That’s the grim warning from Nasa, which has been analysing the atmosphere above the Amazon.

It found that levels of moisture have plunged over the rainforest over the past 20 years and blamed the phenomenon on ‘human activities’.

‘We observed that in the last two decades, there has been a significant increase in dryness in the atmosphere as well as in the atmospheric demand for water above the rainforest,’ said JPL’s Armineh Barkhordarian, lead author of the study.


‘In comparing this trend to data from models that estimate climate variability over thousands of years, we determined that the change in atmospheric aridity is well beyond what would be expected from natural climate variability.’



Barkhordarian said that ‘elevated greenhouse gas levels are responsible for approximately half of the increased aridity’.

The rest is ‘the result of ongoing human activity, most significantly, the burning of forests to clear land for agriculture and grazing’.

These human activities are causing localised warming of the Amazon’s climate and make the ecosystem more vulnerable to fires.

A graphic showing levels of moisture over the Amazon (Image: Nasa)

The during process is made worse by blazes, which release aerosol particles into the atmosphere.

Black carbon, which is more often called soot, has a particularly grim effect because it absorbs the sun’s heat and causes the atmosphere to warm up.

The trend is dangerous because the Amazon absorbs billions of tonnes of carbon dioxide

As the climate of the Amazon heats up, plants release more water to cool themselves down, potentially causing an even greater drying effect.

‘It’s a matter of supply and demand,’ said JPL’s Sassan Saatchi, co-author of the study.

‘With the increase in temperature and drying of the air above the trees, the trees need to transpire to cool themselves and to add more water vapor into the atmosphere. But the soil doesn’t have extra water for the trees to pull in.

‘Our study shows that the demand is increasing, the supply is decreasing and if this continues, the forest may no longer be able to sustain itself.’

It’s feared the Amazon may reach the point where it cannot ‘function properly’, meaning it does not absorb enough carbon dioxide to regulate the climate.

Nasa warned: ‘If this trend continues over the long term and the rainforest reaches the point where it can no longer function properly, many of the trees and the species that live within the rainforest ecosystem may not be able to survive.

‘As the trees die, particularly the larger and older ones, they release CO2 into the atmosphere; and the fewer trees there are, the less CO2 the Amazon region would be able to absorb – meaning we’d essentially lose an important element of climate regulation.’