A new study has revealed that rapid, large-scale day-to-day temperature fluctuations have intensified amid global warming, representing a distinct climate hazard with impacts on human health. This growing volatility creates a weather pattern akin to a "climate roller coaster," exposing populations to more frequent and sharp shifts between temperature extremes.
Conducted by researchers from Nanjing University and the Institute of Atmospheric Physics of the Chinese Academy of Sciences (CAS), the study was recently published in Nature Climate Change.
The study defines such extreme temperature events as occurrences where the temperature difference between two consecutive days exceeds the 90th percentile of historical records. Through analysis, the study finds that these extreme day-to-day temperature changes have become more frequent and intense across low- to mid-latitude regions. Using optimal fingerprinting methods, the researchers confirmed that human-driven greenhouse gas emissions are the primary cause of this trend.
Projections from climate models indicate this trend will continue. Under a high-emission scenario, the frequency and total intensity of these extreme temperature events could rise by approximately 17% and 20% respectively by 2100-impacting regions where more than 80% of the global population lives.
The researchers further uncovered the underlying physical mechanism using the composite change index method. "Global warming exacerbates soil drought and intensifies variability in sea-level pressure and soil moisture," explained Prof. XU Zhongfeng, an author of the study. "These processes reduce the surface's heat capacity and amplify fluctuations in cloud cover and radiation, ultimately leading to more rapid temperature swings."
Notably, the health risks posed by these sudden "roller-coaster" temperature shifts outweigh those associated with other temperature-related variables. Drawing on mortality data from Jiangsu Province, China, and the United States, the study finds that the correlation between these extreme temperature events and all-cause mortality follows a near-exponential pattern. This risk is particularly pronounced for cardiovascular and respiratory diseases.
The researchers emphasize that this phenomenon is distinct from traditional extreme temperature indices. "This study establishes extreme day-to-day temperature change as a distinct and independent category of extreme climate events," stated Prof. FU Congbin, a CAS member from Nanjing University and the corresponding author of the study. "Global warming is systematically intensifying these temperature swings in the world's most populous regions, posing challenges to public health and ecosystem stability. We recommend that relevant international scientific organizations formally recognize it as a new type of extreme weather event."
