The Growing Threat of Extreme Drought‐Heat to the Amazon Carbon Sink

Abstract The Amazon rainforest is a critical regulator of the global carbon cycle, yet its resilience to compound climate extremes remains uncertain. The severe drought–heat event of 2023, marked by record temperatures and hydrological stress, offers an opportunity to examine the vulnerability of Amazon carbon sink under extreme conditions. In this issue, Botía et al. (2026, https://doi.org/10.1029/2025AV001658 ) presents a comprehensive, multi‐constraint assessment of the impact of 2023 drought‐heat extremes on the Amazon carbon cycle. Their synthesis suggests that the Amazon acted as a weak net carbon source in 2023, primarily due to suppressed plant growth during the drought‐affected second half of the year. The study also reveals discrepancies between local flux measurements, basin‐scale inversions, and dynamical global vegetation model (DGVM) simulations, highlighting persistent challenges related to scale dependence, model structure, and representation of drought processes in DGVMs. Together, these findings underscore both the growing vulnerability of the Amazon carbon sink and the urgent need for sustained, integrated observing and modeling systems to constrain its response to future climate extremes.