Assessing the characteristics of net primary production due to future climate change and CO2 under RCP4.5 in China

In this study, the maximal extent of future net primary production (NPP) uncertainties are explored by employing the conditional nonlinear optimal perturbation related to parameters (CNOP-P) approach and the Lund-Potsdam-Jena (LPJ) model based on future climate change assessments, which are provided by 10 general circulation models (GCMs) of the Coupled Model Intercomparison Project 5 (CMIP5) under the Representative Concentration Pathway (RCP) 4.5 scenario at the North-South Transect of Eastern China (NSTEC). The CNOP-P approach produces a scenario of climate change within the feasible bounds that could cause maximal uncertainty of NPP. We find that the future NPP will increase due to changes in climate and atmospheric CO2; however, there is a difference in the extent of the variation resulting from the 10 GCMs and the CNOP-P approach. Future NPPs are estimated from 3.89 Gt C (MRI-CGCM3 model) to 4.51 Gt C (bcc-csml-1 model) using the LPJ model driven by the outputs of 10 GCMs. The estimates of NPP with two CNOP-P-type climate change scenarios are 4.74 Gt C and 5.31 Gt C and are larger than estimates of NPP by the outputs of the 10 GCMs. The above results imply that the terrestrial ecosystem supplies possible conditions for future carbon sinks for all climate change scenarios, especially for the CNOP-P-type climate change scenarios, although the estimates remain uncertain. Stimulative photosynthesis due to high precipitation and restrained autotrophic respiration due to low temperatures may play important roles in the carbon sink due to the CNOP-P-type climate change and CO2 in all climate change scenarios. In addition, it is found that the combination of climate change and increasing CO2 is the main driver of the increase of NPP. (C) 2018 Elsevier B.V. All rights reserved.