A critical concern for plant function has been that higher temperatures will enhance respiration rates, potentially resulting in tropical forests becoming net carbon sources  . Some studies suggest that excessive respiration is less of a concern as respiration rates can acclimate to elevated temperatures over time . Thermal acclimation of respiration has been shown in a seasonally dry neotropical forest , while models indicate that increases in plant respiration could halve by the end of the 21st century through acclimation, thereby partly ameliorating the potential release of carbon from tropical forests . A contrary view is that plant physiological processes, such as the photosynthesis in tropical canopy trees, are already functioning at levels close to or beyond their thermal optimum limits and that any further temperature increase would turn them from a sink into a carbon source . One of the most pressing questions regarding forest responses to increasing atmospheric CO2 levels is whether trees experience enhanced growth rates as a result of the so-called CO2 fertilisation effect . Observed changes in the terrestrial carbon sink and process-based vegetation models indicate that tropical vegetation response to CO2 fertilisation  is combined with other factors such as nitrogen deposition and length of the growing season, while aerosol-induced cooling may also have played a role in enhancing the carbon sink . Contrastingly, evidence for CO2 fertilisation of growth in individual tropical tree species is generally lacking or controversial , or not as substantial as expected . It is, however, widely agreed that the intrinsic water- use efficiency of a tree, that is, the amount of carbon assimilated as biomass per unit of water used, increases under elevated atmospheric CO2 levels owing to the regulation of stomata  . Tropical dry forests  exhibit changes in water-use efficiency , relative to CO2, at least twice as much as tropical moist forests  .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report