The Amazon rainforest is drying out due to rising human activity, leaving the already endangered ecosystem more vulnerable to fires and drought. This was revealed by a NASA study based on data collected over 20 years. NASA scientists at the agency’s Jet Propulsion Laboratory in Pasadena, California, looked at ground and satellite data to track moisture in Amazon rainforest’s atmosphere for this study.
“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.”
Increasing human activity in Amazon, mainly burning of the forests is causing the climate to get warmer. The study showed that the burning of forests results in the release of particles called aerosols into the atmosphere, which includes black carbon or soot and these interfere with rain patterns.
The reason is that these dark aerosols absorb radiation and heat from the sun causing the atmosphere to get warmer, which impacts cloud formation and, consequently, rainfall. The reason that this is worrying is because the Amazon is the largest rainforest on Earth and removes carbon dioxide from the atmosphere to help keep temperatures down and regulate climate.
According to NASA, “rainforests generate as much as 80% of their own rain, especially during the dry season.” But the disruption of this cycle means longer dryer seasons.
“It’s a matter of supply and demand. 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,” said JPL’s Sassan Saatchi, co-author of the study. The worry is that the forests will no longer be able to sustain themselves in the future.
The most significant and systematic drying of the atmosphere has been observed in the southeast region, NASA’s study showed a bulk of deforestation and agricultural expansion is happening. But they also found episodic drying in the northwest Amazon, an area that typically has no dry season.
NASA’s study warns that if this trend continues, many of the trees and the species that live within the rainforest ecosystem will die out. When trees dies, they will release carbon dioxide in the air, and the fewer trees, the less carbon dioxide that the Amazon will absorb, which will spell further disaster for climate regulation on Earth as a whole.