A new study, conducted by scientists at NASA's Jet Propulsion Laboratory, now shows that over the last two decades the atmosphere above the Amazon rainforest is becoming arid. This has left the ecosystem vulnerable to fires and droughts. The study further reveals that the shocking transformation is primarily because of human activities.
The study, "A Recent Systematic Increase in Vapor Pressure Deficit Over Tropical South America," was published in October in Scientific Reports.
Armineh Barkhordarian, lead author of the study, issued a statement on NASA’s website saying that they observed that in the last two decades there has been an increase in the atmospheric dryness as well as in demand for water by the atmosphere above the rainforest.
He further added that on comparing the trend to data from models that look at climate variability over thousands of years, they determined that the change in the atmospheric dryness in beyond what can be expected from natural climate variability.
According to Barkhordarian, elevated greenhouse gas levels are responsible for approximately half of the increased dryness while the rest is due to ongoing human activity. The predominant human activity leading to the devastating after effect is the burning of forests to clear land for agriculture and grazing.
Study authors further point out that the fire releases aerosols -- soot and other particles -- which absorb heat from the sun and contribute to the warming of the atmosphere.
According to the study, while northwest Amazon does not have a dry season, they have experience severe drought for the last two decades as well as a dramatic rise in Amazon forest fires.
The largest rainforest on Earth, the Amazon helps regulate climate by removing CO2 from the atmosphere. Co-author of the study Sassan Saatchi said that with an increase in temperature of the Amazon rainforest and increased aridity of the air above it, the trees need to transpire to cool themselves and add more water vapour to the atmosphere. However, the soil is devoid of any water for the trees and despite increasing demand, there has been a shortage in supply. According to Saatchi, if this continues, the rainforest may not be able to sustain itself for much longer.