Projected shifts in Köppen climate zones over China and its national ecological security shelter zones

Abstract

<p indent="0mm">Based on a set of five regional climate model 21st century climate change simulations, this study assesses future changes in Köppen-Trewartha climate types in China and its five national ecological security shelter zones. The regional climate model, the Abdus Salam International Centre for Theoretical Physics (ICTP) regional climate model RegCM4, is driven by five different global climate models, CSIRO-Mk3-6-0, EC-EARTH, HadGEM2-ES, MPI-ESM-MR and NorESM1-M, at a grid spacing of <sc>25 km</sc> under the representative concentration pathway RCP4.5. These global climate models were selected because of their high horizontal resolution and their good performance in reproducing temperature and precipitation over China. The model configuration used was customized for better performance over China. Bias correction was applied to the simulated temperature and precipitation before calculating the climate types. By the end of the 21st century (2069–2098), the annual mean temperature over China is projected to increase by 2.4°C relatives to the present day (1981–2010) annual mean temperature, with the greatest warming (&gt; <sc>2.8°C)</sc> occurring in the Three Rivers Headwaters region. The annual mean precipitation change shows a general increase in most parts of China, except for a slight decrease (&lt; 7%) in southwestern China. The increase is more pronounced over northwestern China. The distribution of climate types was well reproduced by the simulations. A subtropical humid (Cr) climate mainly covers the regions south of the Yangtze River over eastern China. Southwestern China is dominated by a subtropical winter dry (Cw) climate. The Tibetan Plateau is mostly described as tundra (FT) and arid (type B) climate. Dry arid (BW) and semiarid (BS) climates cover most of the northern regions of 35°N except over northeastern China, where temperate continental (Dc) and subarctic continental (Ec) climates exist. Compared to the present-day climates, a change of 22% in the climate types is projected to occur over the whole Chinese territory by the end of the 21st century. The changes are most significant over the Tibetan Plateau and along the climate transition zone of the Qinling Mountains-Huaihe River over China, with a dominant retreat of FT due to the profound warming and an expansion of BS and Cw being projected for the former, and a replacement of temperature oceanic (Do) by Cw being projected for the latter. Over northeastern China, the main projected change in the climate types is the replacement of Ec by Dc. Tropical wet-dry (Aw) climates will occur over all of Hainan Island. The analysis showed that most changes in climate types are driven by temperature rather than precipitation. For the national shelter zones, climate types will change by 24% over all the areas. Profound changes of ~40% will occur in the shelter zones of the Qinghai-Tibet Plateau and the Sichuan-Yunnan-Loess Plateau, followed by those in the northeastern forest. More specifically, over the Qinghai-Tibet Plateau, the replacement of FT by subarctic oceanic (Eo), BS, Ec, and Dc climates is projected to occur. While FT (62%) and BS (26%) dominate this region currently day, BS (38%) and FT (24%) will account for a greater proportion of the region by the end of the 21st century. The change in climate types on the Sichuan-Yunnan-Loess Plateau is characterized by the expansion of Cw and BS and a loss of FT. Replacement of Ec by Dc is projected in the northeastern forest shelter zone, indicating a major retreat of subarctic coniferous forest there. Greater ecological vulnerability and risks in the future under climate change are expected in the zones. Generally, the changes are in good agreement among the individual simulations, indicating a small uncertainty in the projections.