Terrestrial Gross Carbon Dioxide Uptake: Global Distribution and Covariation with Climate

TLDR

The carbon cycle, driven by gross primary production that removes CO₂ annually, is central to climate change, with 32 % of uptake in tropical forests and precipitation and respiration temperature sensitivity (Q10) influencing global carbon dynamics. Terrestrial plants absorb ~122 billion tons of CO₂ annually, far exceeding fossil fuel emissions (~7 billion tons), and ecosystem respiration has a temperature sensitivity Q10 of 1.6 that is invariant across ecosystems, implying a weaker climate sensitivity than recent models predict. References: Beer et al.; Mahecha et al.

Abstract

Carbon Cycle and Climate Change As climate change accelerates, it is important to know the likely impact of climate change on the carbon cycle (see the Perspective by Reich ). Gross primary production (GPP) is a measure of the amount of CO 2 removed from the atmosphere every year to fuel photosynthesis. Beer et al. (p. 834 , published online 5 July) used a combination of observation and calculation to estimate that the total GPP by terrestrial plants is around 122 billion tons per year; in comparison, burning fossil fuels emits about 7 billion tons annually. Thirty-two percent of this uptake occurs in tropical forests, and precipitation controls carbon uptake in more than 40% of vegetated land. The temperature sensitivity (Q10) of ecosystem respiratory processes is a key determinant of the interaction between climate and the carbon cycle. Mahecha et al. (p. 838 , published online 5 July) now show that the Q10 of ecosystem respiration is invariant with respect to mean annual temperature, independent of the analyzed ecosystem type, with a global mean value for Q10 of 1.6. This level of temperature sensitivity suggests a less-pronounced climate sensitivity of the carbon cycle than assumed by recent climate models.