Climate-driven changes in chemical weathering and associated phosphorus release since 1850: Implications for the land carbon balance

Chemical weathering and associated nutrient release act as a control on atmospheric carbon dioxide (CO2) concentration. To globally quantify the contribution of chemical weathering and associated phosphorus (P) release on the historical trend in terrestrial carbon uptake, we applied a weathering model under climate reconstructions from four Earth System Models. In these simulations, CO2 consumption and P release increased from 1850 to 2005 by 11 +/- 3% and 12 +/- 4%, respectively. Thereby the intensification of weathering due to climate change could have contributed to a small extent to the trend in terrestrial carbon uptake since the pre-Industrial Period. Using a back of the envelope calculation, we found a feedback strength of CO2 consumption and P release of -0.02 +/- 0.01Wm-2K-1 and -0.02 +/- 0.01Wm-2K-1, respectively. Although being one magnitude smaller than the carbon cycle feedback, the weathering feedbacks are comparable in strength to small second-order feedbacks such as methane, fire, or ozone.