Implications of improved representations of plant respiration in a changing climate.

Land-atmosphere exchanges influence atmospheric CO. Emphasis has been on describing photosynthetic CO uptake, but less on respiration losses. New global datasets describe upper canopy dark respiration (R ) and temperature dependencies. This allows characterisation of baseline R , instantaneous temperature responses and longer-term thermal acclimation effects. Here we show the global implications of these parameterisations with a global gridded land model. This model aggregates R to whole-plant respiration R , driven with meteorological forcings spanning uncertainty across climate change models. For pre-industrial estimates, new baseline R increases R and especially in the tropics. Compared to new baseline, revised instantaneous response decreases R for mid-latitudes, while acclimation lowers this for the tropics with increases elsewhere. Under global warming, new R estimates amplify modelled respiration increases, although partially lowered by acclimation. Future measurements will refine how R aggregates to whole-plant respiration. Our analysis suggests R could be around 30% higher than existing estimates.