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

Abstract

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 pre-industrial 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.