Rising temperatures driven by increased carbon emissions have become one of the most dangerous climate risks to public health. Notably, global greenhouse gas emissions have peaked in human history in the last decade (2011−2020), and extreme heat events occur frequently around the world. Hot weather can raise the body's core temperature and heartbeat rate, resulting in heat stroke, respiratory and cardiovascular diseases, and even death.
China, a country with a large population, is experiencing warming beyond the global level. Extreme high-temperature events in China occurred frequently in the past 20 years, causing many deaths. China's intervention in the climate crisis is crucial. Strategic mitigation and adaptation to contain climate change and its impacts will provide significant health benefits for China's 1.4 billion people, and incorporating these strategies into a detailed pathway toward carbon-neutral commitments will ensure improved human well-being. Given the continuing population growth, coupled with rising temperatures, governments should build the necessary health infrastructures to cope with the expected changes and prioritize prevention efforts in the areas where influences are concentrated. Therefore, it is necessary to measure the importance of adaptation to climate change by counting the maximum amount of heat risk that can be avoided by reducing emissions.
For these reasons, using non-accidental mortality records from 195 sites and eleven model simulations from the Coupled Model Intercomparison Project phase 6, we assessed future avoidable heat-related deaths associated with emission mitigation after accounting for population changes in China. Our findings suggest that current heat-related mortality in China is primarily caused by natural climate change, whereas future anthropogenic heat-related mortality will increase by scenario and year, becoming dominant in the next 20−40 years. Without human-induced climate change in the 21st Century, China's heat-related mortality would drop by 48−72% [95% confidence interval (CI): 40−76%], especially at high latitudes and high altitudes (up to 80%). Nationally, it is possible to avoid 15,576-87,612 (95% CI: 6,605-106,736) heat-related deaths per year by reducing emissions. For most of China, temperature changes dominate the variation in heat-related deaths, while in Central and South China, population changes will have a greater influence. These not only reinforce the necessity of mitigating emissions but also suggest that adjusting population structure and spatial distribution could be applied in some areas to minimize warming impacts on public health.
Notably, heat-related deaths in China over the next 20 years are very similar across the high, medium and low emission scenarios. This may be due to the long-term global warming having caused some short-term irreversibility, resulting in current emission reductions being unlikely to provide immediate benefits for thermal risk mitigation. Therefore, more healthcare infrastructures are urgently needed to manage potential growing heat risks. Particularly in Northwest and South China, where future heat-related deaths would still be 110−140% of current levels (1995−2014) even without anthropogenic warming. We also found that without historical human-induced emissions, China's low level of technology (medical and economic) might increase current heat-related mortality by 57%, even though warming could be mitigated. Consequently, we believe that mitigating climate change risks also requires consideration of the economic/medical losses from lowering emissions.
Our results provide a comprehensive and up-to-date projection of heat-related health risks in China for strategic planning and prioritization of health infrastructure needs to effectively adapt to global warming and cope with future population growth. The methodology used to assess future avoidable heat-related deaths may be readily applicable to other parts of the world to address similar issues.