When it comes to regulating Earth’s climate, few ecosystems play a more important role than the Amazon rainforest. But what happens when global warming dramatically alters the Amazon’s climate?

A study suggests a major shift is already underway. The findings show that the Amazon is transitioning to a new “hypertropical” climate with unprecedented hot drought conditions (severe dry spells amplified by extreme heat) that haven’t been seen on Earth for tens of millions of years. This shift is a direct result of rising global temperatures, the researchers concluded.

By 2100, the rainforest could experience up to 150 days of hot drought conditions each year, potentially leading to mass tree die-offs, according to the study. This exposes a dangerous feedback loop: As human-driven climate change stresses the Amazon, the rainforest’s capacity to mitigate climate change is shrinking.

The Amazon is one of the world’s largest carbon sinks. Its hundreds of billions of tropical trees remove massive amounts of carbon dioxide from the atmosphere, storing it in their biomass and the soil. Still, humans are emitting greenhouse gases far faster than the Amazon and other natural carbon sinks can absorb them, causing the global temperature to rise.

As climate change intensifies extreme weather events such as hot droughts, more trees are succumbing to stress. At the same time, rampant deforestation is clearing large swaths of the Amazon. This not only decreases the rainforest’s capacity to absorb carbon but also emits large amounts of carbon as dead trees decompose. It’s a double whammy.

A 2021 study found that the southeastern portion of the Amazon is already emitting more carbon than it absorbs, and scientists worry that the whole rainforest could soon follow suit. This new study underscores such concerns, showing that the Amazon’s climate is transitioning to a state most trees won’t be able to survive.

In just 75 years, this could be the Amazon’s new normal. The only way to slow this transition is to reduce greenhouse gas emissions and slow global warming. The question now is whether the global community will act or allow the Amazon to morph into an ecosystem that cannot survive.