Absolute Contribution of the Non-Uniform Spatial Distribution of Atmospheric CO2 to Net Primary Production through CO2-Radiative Forcing

Jing Peng,Xiba Tang,Jinming Feng,Fuqiang Yang,Kairan Ying,Li Dan

doi:10.3390/su131910897

Abstract

Atmospheric concentrations of CO2 are the most important driver of the Earth’s climate and ecosystems through CO2-radiative forcing, fueling the surface temperature and latent heat flux on half-century timescales. We used FGOALS-s2 coupled with AVIM2 to estimate the response of net primary production (NPP) to spatial variations in CO2 during the time period 1956–2005. We investigated how the induced variations in surface temperature and soil moisture influence NPP and the feedback of the oceans and sea ice on changes in NPP. The spatial variations in the concentrations of CO2 resulted in a decrease in NPP from 1956 to 2005 when we included ocean and sea ice dynamics, but a slight increase in NPP without ocean and sea ice dynamics. One of the reasons is that the positive feedback of sea temperature to the surface temperature leads to a significant decrease in tropical NPP. Globally, the non-uniform spatial distribution of CO2 absolutely contributed about 14.3% ± 2.2% to the terrestrial NPP when we included ocean and sea ice dynamics or about 11.5% ± 1.1% without ocean and sea ice dynamics. Our findings suggest that more attention should be paid to the response of NPP to spatial variations in atmospheric CO2 through CO2-radiative forcing, particularly at low latitudes, to better constrain the predicted carbon flux under current and future conditions. We also highlight the fundamental importance of changes in soil moisture in determining the pattern, response and magnitude of NPP to the non-uniform spatial distribution of CO2 under a warming climate.

Highlights

Atmospheric CO2 concentrations are one of the most important drivers of climate in earth system models [1,2]
We addressed three principal questions: (1) how much does the climate-driven feedback caused by the non-uniform spatial distribution of CO2 through CO2 -raiative forcing affect climate variables and net primary production (NPP); (2) how does the estimated NPP with and without ocean and sea ice dynamics differ as a result of the nonuniform spatial distribution of CO2 through the radiative forcing associated with spatial variations in the climate variables; and (3) what are the implications of a non-uniform spatial distribution of CO2 on the global NPP during the time period 1956–2005
Our analysis showed an effect of the non-uniform spatial distribution of CO2 on NPP without considering land use of up to 14.26 ± 2.22% of the NPP simulated by a fully coupled model

Summary

Introduction

Atmospheric CO2 concentrations are one of the most important drivers of climate in earth system models [1,2] It can affect the global average surface temperature, the global water cycle, global sea-levels, the loss of Arctic sea ice and the atmospheric vapor pressure deficit through radiative forcing [3,4,5]. There is large uncertainty in the magnitude and spatial distribution of the radiative effect of atmospheric CO2 concentration (±20%) based on multi-model simulations [7,8]. These models come from the fifth stage of the coupled model comparison project (CMIP5) [9]. The spatial heterogeneity of atmospheric CO2 concentrations varies widely on a regional scale [10,11], the contribution of spatially non-uniform CO2 to the Earth’s climate and the terrestrial carbon cycle through CO2 -radiative forcing is largely unknown [12]

Methods

Results

Discussion

Conclusion