A model analysis of the relationship between climate perturbations and carbon budget anomalies in global terrestrial ecosystems: 1970 to 1997

Climate Research

Akihiko Ito¹  Takehisa Oikawa¹ 

关键词: Carbon budget;    Terrestrial ecosystem;    Net ecosystem production (NEP);    Interannual change;    Climatic perturbation;    Model analysis;   

DOI  :  10.3354/cr015161

来源: Inter-Research Science Publishing

【 摘 要 】

ABSTRACT: We performed a model analysis of the effect of climatic perturbations from 1970 to 1997 on the carbon budget of terrestrial ecosystems at the global scale. The model, Sim-CYCLE, enabled us to simulate carbon storage in terrestrial pools andmonthly carbon fluxes between the atmosphere and the biosphere, e.g. photosynthesis, respiration, decomposition, and net ecosystem production (NEP). For the global analysis, we adopted the Matthews biome distribution map (12 biome types) and the USNational Centers for Environmental Prediction and the US National Center for Atmospheric Research (NCEP/NCAR) reanalysis climate dataset, which is at a spatial resolution of T62 (5828 land cells). During the 28 yr experimental period, global NEP showedconsiderable climate-induced interannual anomalies (NEPs) ranging from -2.06 Pg C yr^-1 (source) in 1983 to +2.25 (sink) Pg C yr^-1 in 1971, being sufficiently large to give rise to anomalies in the atmospheric CO₂concentration from +0.97 to -1.06 ppmv. Regression analyses demonstrated the following: (1) annual NEPs had the highest correlation (r² = 0.38) with the temperature anomaly at the global scale; (2) the anomalies in precipitation resulted in aconsiderable NEP in northern high and middle regions; (3) an anomalous global warming by +1°C brought about a negative NEP of -2.7 Pg C yr^-1; (4) the responsiveness was primarily attributable to the temperature sensitivities of plantrespiration and soil decomposition, and secondarily to the moisture sensitivity of decomposition; and (5) the temperature dependence of NEP had a clear seasonality, i.e. most sensitive in July to September (summer in the northern hemisphere) relative toother seasons. In 1983, when an ENSO event happened and the tropical zone was anomalously hot (0.4°C above the long-term mean), the largest negative NEP (-2.06 Pg C yr^-1) was estimated. On the other hand, in 1971, when global mean temperaturewas relatively low (0.2°C below the long-term mean), the largest positive NEP (+2.25 Pg C yr^-1) was estimated. Furthermore, in 1992, when an anomalous cooling during the growing period (0.3°C below the long-term mean) was caused by the Mt.Pinatubo eruption (June 1991), a considerable positive NEP (+1.14 Pg C yr^-1) was estimated. The climate dependencies of global terrestrial ecosystems analyzed here may contain significant implications not only for the present functioning ofatmosphere-biosphere carbon exchange, but also for ongoing global warming.

【 授权许可】

Unknown