Why did the Amazon become a carbon source in 2023?
What flipped the Amazon's carbon balance in 2023
In 2023 the Amazon, long regarded as a major carbon sink, emitted more carbon than it absorbed. Satellite and climate‑model analyses attribute that reversal primarily to an extreme regional drought and anomalously high temperatures. During that year average temperatures across parts of the basin were about 1.5°C above the 1991–2020 baseline, and vegetation stress reduced the forest’s ability to take up CO₂ from the atmosphere.
Key drivers identified:
- Severe drought reduced photosynthesis and the growth of leaves and wood, cutting the forest’s carbon uptake.
- Heat stress intensified respiration and plant mortality, releasing stored carbon back to the air.
- Fire activity did contribute to emissions, but analyses indicate weakened vegetation uptake played the larger role in turning the region into a net source.
Estimates of the excess carbon released vary across studies, but one analysis put the upper bound at roughly 170 million tonnes of CO₂ for 2023. That magnitude is large enough to alter the global carbon budget for the year and highlights the Amazon’s vulnerability to extreme climate events.
Why it matters
- A persistent shift from sink to source would accelerate atmospheric CO₂ growth and make climate mitigation harder.
- The event shows that large tropical forests can rapidly lose their buffering capacity under compound stresses (heat + drought), which raises concern about tipping points.
What’s uncertain
- Whether the 2023 flip is temporary — forests can recover given wetter, cooler conditions — or the start of a longer trend depends on future climate extremes and land‑use pressures.
- Recovery trajectories vary by region and depend on fire frequency, deforestation, and soil and species responses.
Scientists call for strengthened monitoring, protections against deforestation and fires, and faster cuts to fossil‑fuel emissions to reduce the risk of more frequent flips.