Elevated sea temperatures drove regional warming beyond 1.5 degrees Celsius.
Prolonged drought weakened Amazon’s carbon absorption capacity.
Forest shifted from sink to carbon source temporarily.
Ocean Warming Leads to Unusual Dryness
According to the researchers, the region experienced unusually dry air for the three months due to warmer ocean waters. According to the study, severe drought conditions in the second half of 2023 were caused in part by decreased moisture transport from the Atlantic to South America.
Scientists combined multiple data sources to analyse the Amazon’s carbon balance at different spatial scales. These included atmospheric carbon dioxide measurements, eddy covariance flux data from the Amazon Tall Tower Observatory (ATTO), computer simulations using Dynamic Global Vegetation Models, and satellite remote sensing.
3 February 2026
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The report further stated that the shift occurred even though there was an extended fire emissions in 2023 lasting until November, rather than the usual October end. However, the number of fires recorded remained within the normal range observed over the past two decades (2003-2023).
“A stronger‐than‐normal vegetation uptake early in the year (January-April), consistent across data streams and spatial scales, mitigated the total carbon losses by the end of the year. We find a shift from carbon sink to source in May and a peak source in October,” the authors told Down To Earth.
Tipping Point Risks
The results are in line with more general cautions issued by the Intergovernmental Panel on Climate Change (IPCC), which has warned that extended drought and warming may cause some areas of the Amazon to reach a tipping point and lose their ability to act as carbon sinks.
In addition, 2023 was one of the hottest years on record worldwide, according to the World Meteorological Organization, which exacerbated ocean-atmosphere interactions.
Scientists have long cautioned that long-term hydrological stress and temperature anomalies have the potential to change tropical forests from carbon absorbers to net emitters.
