Evolution and attribution analysis of extreme climate under global warming and urbanization: based on observed data from Suqian City during 1955—2024

Abstract

[Objective] The evolution patterns of extreme climate in cities within the north-south climate transition zone are revealed, thereby providing scientific support for disaster prevention and mitigation, water resources regulation, and climate resilience construction in Suqian City. [Methods] Daily temperature and precipitation observation data from four meteorological stations in Suqian during 1955—2024 were used. Linear trend analysis, the Mann-Kendall test, the trend-free pre-whitening MK test, and the Pettitt abrupt change test were applied to identify evolution characteristics of climatic series. A system consisting of 44 extreme climate indicators was constructed to analyze evolution patterns of extreme precipitation, extreme temperature, and compound extreme events. Partial correlation analysis, stepwise regression, piecewise multiple regression, and hierarchical variance decomposition were used to quantify the effects of three driving factors, namely, global warming, atmospheric circulation, and urbanization. [Results] Over the past 70 years, no significant trend or abrupt change was detected in annual total precipitation, while a remarkable transformation was observed in precipitation structure. The frequency of moderate rainfall events decreased, and the proportions of rainstorms, short-duration extreme precipitation, and nighttime precipitation continuously increased, leading to shorter and more evenly distributed precipitation processes. The annual average temperature increased extremely significantly at a rate of 0. 28~0. 38 ℃ per decade, and consistent abrupt changes occurred across the whole study area in 1993. Diurnal asymmetric warming characteristics were observed. The warming rate of nighttime low temperature was significantly higher than that of daytime temperature, and the diurnal temperature range was continuously reduced. The reduction in cold events was far greater than the increase in warm events. Dry-warm and dry-cold compound extreme events were dominant, while warm-wet and cold-wet events occurred at very low frequencies, indicating a shift in climate risk from cold-dry dominance to warm-dry dominance. According to variance decomposition result, an independent variance contribution of 23. 2% was obtained for global warming, and independent contributions of 3. 1% and 8. 8% were obtained for large-scale atmospheric circulation and local urbanization, respectively. A total of 13. 4% of temperature variation was explained by multi-factor coupling interaction. Piecewise regression result showed that the local response intensity of regional climate to atmospheric circulation and global warming was weakened by rapid urbanization, and no significant linear warming effect was detected for urbanization. [Conclusion] A systematic transformation of climate features is identified in Suqian during 1955—2024, with diurnal asymmetric warming, intensified extreme precipitation, and warm-dominated compound climate risks as the three core characteristics. Global warming dominates regional temperature variations. Urbanization alters climate conditions only through long-term cumulative effects, whereas its marginal warming effect is insignificant. The findings can provide a reference for climate adaptation and disaster prevention in similar cities within the north-south climate transition zone.

Keywords

precipitation structure transformation / diurnal asymmetric warming / extreme climate / compound extreme events / Suqian City / north-south climate transition zone / climate attribution / rainfall