Severe dry seasons, in turn, cause more forest loss, releasing carbon into the atmosphere. Photo: B. Flores

Extreme Amazon drought and deforestation are priming the it’s rainforest

Amazon deforestation leads to increasingly severe dry seasons

A deadly trifecta of deforestation, drought, and escalating global climate change — each impacting the others — threatens to pull the plug on the region’s plentiful precipitation, possibly crashing the biome since the Amazon rainforest depends on its rain cycle to survive and thrive. It’s a phenomenon scientists call a positive feedback loop: deforestation causes drought, which in turn, worsens deforestation, and so on, intensifying the effect.

The study concluded that deforestation causes 4% of drought, while drought accounts for 0.13% of deforestation per millimeter of rain in the Amazon biome. This means that if rainfall in the region decreases by 200 millimeters (7.9 inches), it would then trigger an additional 26% increase in deforestation, according to the findings.

Amazon experts applauded the study’s novelty but also told Mongabay they believed the actual percentages are likely higher and greatly depend on political decisions going forward.

“Widespread drought conditions in 2021 are a worrisome sign that extreme fire risk could affect a large part of South America, straining firefighting resources and threatening ecosystems, infrastructure, and public health,” said Douglas Morton, a NASA Earth scientist who studies fires in the Amazon and surrounding areas.

Most large fires in the Amazon are started by humans on recently cleared land. And deforestation for logging, mining, and farming fragments the forest, experts say, making it more susceptible to catching fire on its edges.

“The edge of a forest is warmer and drier than large tracts of unfragmented forest, so fires are more likely to start at the edges and move into the forest,” said Marcos Heil Costa, a professor at the Federal University of Viçosa in Brazil.

Deforestation was up 67% in May compared to last year, according to the Instituto National de Pesquisas Espaciais. This year’s fresh kindling is on top of what was cut down last year when around 10,900 square kilometers — an area larger than 2 million US football fields — slashed mainly for cattle ranching, farmland, and timber production.

The drought could also exacerbate the situation in the Paraná River basin — home to the continent’s second-longest river, key shipping routes, and hydropower stations — most of which is already in moderate to extreme drought, according to the alert. Last year, low water levels grounded several ships, forcing some to offload cargo to navigate the shallow river.

Few ecosystems on Earth are as critical to the global climate as the Amazon rainforest.

Its vast tree canopy serves as an “air conditioner” for the planet, scientists say, influencing global temperature and rainfall patterns. Through photosynthesis, the plants and trees of the Amazon absorb billions of tons of carbon dioxide from the air each year, which helps limit how much of the heat-trapping gas is in the atmosphere.

But when it burns, the carbon that is stored in the forest is released into the air, where it can stay for hundreds of years and contribute to even more global warming.

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