Reduced Vegetation Uptake During the Extreme 2023 Drought Turns the Amazon Into a Weak Carbon Source

Overview

The 2023 Amazon region experienced extreme drought conditions characterized by temperature anomalies of 1.5°C above the 1991-2020 baseline during September-November, driven by elevated sea surface temperatures in the Atlantic and Pacific and reduced Atlantic moisture advection. This study evaluates the Amazon carbon cycle response to this extreme event using integrated observational and modeling frameworks spanning multiple spatial scales.

Methods and approach

The analysis integrated atmospheric CO2 mole fractions and eddy covariance flux measurements from the Amazon Tall Tower Observatory (ATTO), Dynamic Global Vegetation Models (DGVMs) with low-latency simulations, atmospheric inversion techniques, and remote sensing products. This multi-source data integration enabled assessment of carbon fluxes across temporal scales from daily observations to regional atmospheric inversions, with comparison to the 2003-2023 historical record to contextualize 2023 fire emissions and vegetation responses.

Key Findings

The Amazon region functioned as a net carbon source of 0.01-0.17 PgC in 2023, with fire emissions of 0.15 [0.13-0.17] PgC representing typical variability within the 2003-2023 period. The carbon source was attributable to reduced vegetation uptake during the August-October dry season rather than anomalous fire activity. Earlier in the year (January-April), vegetation carbon uptake exceeded normal conditions across all data streams and spatial scales, partially offsetting late-year carbon losses. The region transitioned from carbon sink to source in May, reaching peak emissions in October.

Implications

The 2023 drought demonstrated the Amazon's vulnerability to hydrological extremes through vegetation uptake suppression rather than fire-driven emissions. The shift from sink to source status during the dry season indicates that climate-driven water stress can decouple vegetation productivity from typical seasonal patterns. This response mechanism represents a critical pathway through which future droughts could alter the Amazon's carbon balance independent of fire activity.

Scope and limitations

This summary is based on the study abstract and available metadata. It does not include a full analysis of the complete paper, supplementary materials, or underlying datasets unless explicitly stated. Findings should be interpreted in the context of the original publication.