Amazon Rainforest Flipped From Carbon Sink to Carbon Source During 2023 Drought

Amazon Becomes a Carbon Emitter

The world's largest rainforest reversed its role as a carbon absorber during 2023's extreme drought, releasing millions of tons of carbon into the atmosphere instead of storing it, according to new research published in AGU Advances by an international team led by Santiago Botia at the Max Planck Institute for Biogeochemistry.

The study found that the Amazon released between ten and one hundred and seventy million tons of carbon in 2023, accounting for roughly thirty percent of net carbon emissions from all tropical lands that year.

Drought and Heat, Not Fire

Researchers combined data from the Amazon Tall Tower Observatory, satellite observations, and vegetation models to track carbon flows across the basin. They found that unusually high temperatures in 2023, reaching one point five degrees Celsius above the 1991 to 2020 average, combined with severe atmospheric dryness from September to November caused vegetation to dramatically reduce carbon absorption.

Critically, fire activity remained within normal levels measured over the past two decades, meaning the carbon release was driven primarily by weakened plant photosynthesis rather than burning.

Deforestation Amplifies the Problem

Separate research has documented how forest loss is reshaping the Amazon's climate. Heavily deforested areas experience surface temperatures up to three degrees Celsius higher during the dry season compared to regions with more than eighty percent forest cover. Areas with less than sixty percent forest cover now share climatic characteristics with savanna transition zones, including twenty-five percent less rainfall.

A Forest on the Edge

The Brazilian Amazon has lost approximately five hundred and twenty thousand square kilometres of native vegetation since 1985. While deforestation rates have fallen in recent years, reaching an eleven-year low ahead of COP30 in Belem, fires destroyed record amounts of primary forest in 2024. Scientists warn that between ten and forty-seven percent of the Amazon could face compounding disturbances that may trigger unexpected ecosystem transitions by 2050.