Implications of improved representations of plant respiration in a changing climate

Land-atmosphere exchanges influence atmospheric CO2. Emphasis has been on describing photosynthetic CO2 uptake, but less on respiration losses. New global datasets describe upper canopy dark respiration (R-d) and temperature dependencies. This allows characterisation of baseline R-d, 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-d to whole-plant respiration R-p, driven with meteorological forcings spanning uncertainty across climate change models. For preindustrial estimates, new baseline R-d increases R-p and especially in the tropics. Compared to new baseline, revised instantaneous response decreases R-p for mid-latitudes, while acclimation lowers this for the tropics with increases elsewhere. Under global warming, new R-d estimates amplify modelled respiration increases, although partially lowered by acclimation. Future measurements will refine how R-d aggregates to whole-plant respiration. Our analysis suggests R-p could be around 30% higher than existing estimates.