Projecting impacts of climate change on global terrestrial ecoregions

Terrestrial ecoregions, including critical ecoregions (CEs), vulnerable ecoregions (VEs), and intact ecoregions (IEs) have been used by the World Wildlife Fund (WWF) to classify global biodiversity and are being affected by climate change, which was considered as one of the main threats to biodiversity conservation. However, the impacts of future climate change in shifted means and extremes of temperature, precipitation, and cloud cover under the representative concentration pathways (RCP 2.6, 4.5, and 8.5) on the characteristics of these ecoregions have yet to be fully understood. The present study was designed using a dynamic global vegetation model and both current and future climate scenarios, to investigate the impacts of shifted means and extremes of temperature, precipitation, and cloud cover on five ecological indicators including net primary productivity (NPP), carbon storage, runoff, wildfire risk, and habitat transformation at the ecoregional scale. The analysis was performed for the terrestrial ecoregions as a whole, as well as for specific subsets of CEs, VEs, and IEs. The results showed that future climate scenarios (whether RCP 2.6, 4.5, or 8.5) were estimated to increase the mean NPP, runoff, wildfire risk, and habitat transformation for all ecoregion types, when comparing values for 2071-2100 to the baseline (1971-2000) period. In contrast, the mean carbon storage in the TEWs, VEs, and CEs was estimated to decrease from the baseline to the values under RCP 2.6 and RCP 4.5 and then increase to their largest values under RCP 8.5. The mean carbon storage in the IEs under RCP 8.5 was estimated to remain lower than the baseline period values. Climate change in shifted means and extremes of temperature, precipitation, and cloud cover are generally significant drivers of the variances of NPP, carbon storage, runoff, wildfire risk, and habitat transformation under RCP 2.6, RCP 4.5, and RCP 8.5. The dynamics of the climate change metrics and the five ecological indicators have significant implications for biodiversity conservation in changing climates.