Figure 1: Feedback between climate and the carbon cycle.

Randerson et al.¹ have used a computational model to show that the ocean's contribution to feedback between climate and the carbon cycle increases considerably over time, and exceeds contributions from land by the year 2100. The bar chart shows, for different periods, the reduction in the uptake of anthropogenic carbon (measured in petagrams of carbon; 1 petagram is 10¹⁵ grams) by the ocean and the land biosphere that is attributable to climate change, per increase in global mean surface air temperature of 1 °C. The authors computed these sensitivities from differences in cumulative carbon flux and global mean surface air temperature between a simulation in which CO₂ influences climate and another in which the direct influence of CO₂ on global warming is suppressed.