The Role of Terrestrial Phosphorus Limitation in Carbon Cycle-Climate Feedbacks

Phosphorus (P) limitation could play important roles in affecting CO2 concentration-carbon (C) cycle and climate-carbon feedbacks in the Earth system. In this study, we analyzed two types of the Energy Exascale Earth System Model (E3SM) 1% CO2 simulations. One includes carbon-nitrogen (CN) coupling, and the other includes carbon-nitrogen-phosphorus (CNP) coupling. Our results showed that (1) CNP and CN simulated different climate state, especially for the surface temperature; (2) the differences in NPP between the CNP and CN simulations are highly correlated with the differences in climate at a 90% confidence level over most P limited areas; (3) P limitation usually reduces plant net primary production (NPP) and leaf area index (LAI); however, the P limitation-soil moisture feedback (reduced productivity and evapotranspiration due to P limitation leads to increases in soil moisture) may increase the mineral nitrogen (N) and P available to plants and therefore leads to increased NPP and LAI. This feedback is particularly important in the tropics.