Terrestrial ecosystems response to future changes in climate and atmospheric CO2 concentration

[摘要] The response of the terrestrial carbon cycle to future changes in climate andatmospheric CO₂ is assessed by analysing simulation results for the2006–2100 period made with the second generation Canadian Earth system model(CanESM2) for the RCP 2.6, RCP 4.5 and RCP 8.5 climate change scenarios. Ourinterest is in the extent to which global terrestrial carbon pools and sinks,in particular those of the Amazonian region, are vulnerable to the adverseeffects of climate change. CanESM2 results indicate that land remains anoverall sink of atmospheric carbon for the 2006–2100 period. The net carbonuptake by land in response to changes in climate and atmospheric CO₂ isclose to 20, 80 and 140 Pg C for the RCP 2.6, 4.5 and 8.5 scenarios,respectively. The latitudinal structure of future atmosphere–land CO₂flux remains similar to that observed for the historical period with northernmid- to high-latitude regions gaining carbon from the atmosphere while thetropics remain either carbon neutral or a modest source of atmospheric carbondepending on scenario. These changes occur in conjunction with simulatedprecipitation and soil moisture increases over northern mid- andhigh-latitude land regions and precipitation and soil moisture decreases overthe South American continent in all scenarios. Compared to other regions ofthe globe, which are either carbon sinks or near neutral, the Amazonianregion is simulated to be a net source of carbon during the 21st century.Moreover, and unexpectedly, the rate of carbon loss to the atmosphere fromthe Amazonian region is largely independent of the differences between thethree scenarios considered.

[学科分类] 地球化学与岩石