Amazon Rainforest Becomes a Carbon Source During 2023 Extreme Drought, New Study Reveals

The Amazon rainforest, traditionally a massive carbon sink, became a significant carbon source during the extreme drought of 2023. This shift in carbon dynamics has profound implications for global climate and the role of the Amazon in mitigating climate change.

In a groundbreaking study, researchers have found that the Amazon rainforest, traditionally a massive carbon sink, became a significant carbon source during the extreme drought of 2023. This shift in carbon dynamics has profound implications for global climate and the role of the Amazon in mitigating climate change.

According to the study led by Santiago Botia at the Max Planck Institute for Biogeochemistry, the Amazon rainforest released between 10 and 170 million tons of carbon in 2023, instead of absorbing it as it typically does. This unprecedented change was primarily caused by an extreme combination of high temperatures and low humidity, which diminished the forest’s ability to absorb carbon. The 2023 drought, which resulted in temperatures 1.5°C higher than the 1991–2020 average, was exacerbated by warmer ocean waters in the Atlantic and Pacific, which reduced moisture transport to the region.

The study used an integrated approach to analyze the carbon cycle of the Amazon, combining data from various CO₂ measurement techniques at the Amazon Tall Tower Observatory (ATTO), satellite data on vegetation status, and computer simulations. The results showed that the rainforest experienced a shift from being a carbon sink to a carbon source, particularly during the months of May to October, when the combination of high temperatures and low humidity weakened the vegetation's carbon uptake capacity.

While fire activity during this period was within normal levels, it was the diminished vegetation absorption that was primarily responsible for the carbon emissions. "The anomalous carbon release in 2023 was mostly due to weakened vegetation uptake, rather than increased fire activity," said Professor Susan Trumbore, head of the ATTO project in Germany.

The Amazon's carbon uptake from January to April was higher than usual, which helped reduce the total carbon loss by the end of the year. However, the researchers found that by October, the rainforest had reached a peak carbon release, which contributed significantly to global carbon emissions.

The study also highlighted that the Amazon’s reduced ability to absorb carbon accounted for 30% of the net carbon emissions from all tropical regions in 2023. These findings underscore the growing vulnerability of the Amazon to climate extremes, a worrying trend that could escalate as global temperatures continue to rise.

Located in the central Brazilian Amazon, the Amazon Tall Tower Observatory has been a crucial site for understanding carbon cycles in the region, providing valuable in-situ data. The findings from the ATTO station offer vital insights into how rainforests and adjacent ecosystems respond to extreme climate conditions, serving as an indicator of how the rainforest may behave under continued global warming.

As scientists eagerly await further data from the years following 2023, the implications of these findings are clear: the Amazon's ability to mitigate climate change is being tested, and its future role as a carbon sink remains uncertain in the face of extreme climate events.