Shukla Krishna Kumar, Attada Raju
Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research Mohali, SAS Nagar, Manauli, Sector 81, Knowledge city, 140306, Punjab, India.
Sci Rep. 2023 Aug 2;13(1):12549. doi: 10.1038/s41598-023-38602-y.
The frequency and intensity of extreme thermal stress conditions during summer are expected to increase due to climate change. This study examines sixteen models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) that have been bias-adjusted using the quantile delta mapping method. These models provide Universal Thermal Climate Index (UTCI) for summer seasons between 1979 and 2010, which are regridded to a similar spatial grid as ERA5-HEAT (available at 0.25° × 0.25° spatial resolution) using bilinear interpolation. The evaluation compares the summertime climatology and trends of the CMIP6 multi-model ensemble (MME) mean UTCI with ERA5 data, focusing on a regional hotspot in northwest India (NWI). The Pattern Correlation Coefficient (between CMIP6 models and ERA5) values exceeding 0.9 were employed to derive the MME mean of UTCI, which was subsequently used to analyze the climatology and trends of UTCI in the CMIP6 models.The spatial climatological mean of CMIP6 MME UTCI demonstrates significant thermal stress over the NWI region, similar to ERA5. Both ERA5 and CMIP6 MME UTCI show a rising trend in thermal stress conditions over NWI. The temporal variation analysis reveals that NWI experiences higher thermal stress during the summer compared to the rest of India. The number of thermal stress days is also increasing in NWI and major Indian cities according to ERA5 and CMIP6 MME. Future climate projections under different scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5) indicate an increasing trend in thermal discomfort conditions throughout the twenty-first century. The projected rates of increase are approximately 0.09 °C per decade, 0.26 °C per decade, and 0.56 °C per decade, respectively. Assessing the near (2022-2059) and far (2060-2100) future, all three scenarios suggest a rise in intense heat stress days (UTCI > 38 °C) in NWI. Notably, the CMIP6 models predict that NWI could reach deadly levels of heat stress under the high-emission (SSP5-8.5) scenario. The findings underscore the urgency of addressing climate change and its potential impacts on human well-being and socio-economic sectors.
由于气候变化，预计夏季极端热应激条件的频率和强度将会增加。本研究考察了耦合模式比较计划第六阶段（CMIP6）中的16个模式，这些模式已使用分位数增量映射方法进行了偏差调整。这些模式提供了1979年至2010年夏季的通用热气候指数（UTCI），并使用双线性插值法将其重新网格化到与ERA5-HEAT类似的空间网格（空间分辨率为0.25°×0.25°）。评估将CMIP6多模式集合（MME）平均UTCI的夏季气候学特征和趋势与ERA5数据进行比较，重点关注印度西北部（NWI）的一个区域热点。采用超过0.9的模式相关系数（CMIP6模式与ERA5之间）值来推导UTCI的MME平均值，随后用于分析CMIP6模式中UTCI的气候学特征和趋势。CMIP6 MME UTCI的空间气候学平均值显示，与ERA5类似，NWI地区存在显著的热应激。ERA5和CMIP6 MME UTCI均显示NWI地区的热应激条件呈上升趋势。时间变化分析表明，与印度其他地区相比，NWI在夏季经历的热应激更高。根据ERA5和CMIP6 MME的数据，NWI和印度主要城市的热应激天数也在增加。不同情景（SSP1-2.6、SSP2-4.5和SSP5-8.5）下的未来气候预测表明，整个21世纪热不适状况呈上升趋势。预计的升温速率分别约为每十年0.09℃、每十年0.26℃和每十年0.56℃。评估近期（2022-2059年）和远期（2060-2100年）的未来，所有三种情景均表明NWI地区的高强度热应激天数（UTCI>38℃）将会增加。值得注意的是，CMIP6模式预测，在高排放（SSP5-8.5）情景下，NWI的热应激可能达到致命水平。研究结果强调了应对气候变化及其对人类福祉和社会经济部门潜在影响的紧迫性。
