Accelerated China’s cold regions contraction under climate warming

Cold regions are vital to the Earth system, influencing water storage, energy balance, and ecological stability. China’s diverse terrain includes extensive cold regions that are shrinking due to global warming, with profound implications for climate resilience. Despite their importance, comprehensive assessments of these regions’ past trends and future projections are lacking. This study employs an array of data, including gridded daily dataset (CN05.1), China Meteorological Forcing Dataset (CMFD), European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5-Land (ERA5-Land), and original and bias-corrected outputs from Coupled Model Intercomparison Project Phase 6 (CMIP6) global climate models (GCMs), to analyze the historical (1979–2016) and projected (2015–2100) dynamics of China’s cold regions under different emission scenarios. Our findings indicate that from 1979 to 2016, China’s cold regions covered an average of 3.87 million km², or 40.4 % of China’s land area, with the most substantial areas located in the Tibetan Plateau, Tianshan and Pamirs mountain ranges, and the northeastern region. These regions experienced a significant decline, at a rate of 154,000 km² per decade. Future projections based on bias-corrected CMIP6 data suggest an accelerating contraction, with estimates ranging from a decrease of 54,000 km² per decade under the SSP126 scenario to 210,000 km² per decade under the SSP585 scenario. By the end of the 21st century, the cold regions’ extent could diminish by more than 50 % under the high-emission SSP585 scenario compared to the historical baseline. The analysis shows that nearly 95 % of variations in the extent of China’s cold regions can be attributed to shifts in areas with an annual average temperature at or below 5 °C. These results underscore the need for urgent climate adaptation strategies, particularly as China’s cold regions continue to shrink in response to climate warming driven by human-induced emissions.