Rapid Changes in Land‐Sea Thermal Contrast Across China's Coastal Zone in a Warming Climate

Abstract

Coastal areas are important sites of environmental and socioeconomic activities and are significantly influenced by climate change. Here we analyzed the current and future responses of spatiotemporal characteristics of land‐sea thermal contrast (LSTC) along China's coastal zone to global warming. Using the European Centre for Medium‐Range Weather Forecasts Re‐Analysis (ERA)‐Interim and 18 Coupled Model Intercomparison Project 5 models, we find that the rate of global warming significantly influenced the LSTC in summer. The LSTC first decreased and then increased during the warming and hiatus periods, respectively. In winter, the LSTC decreased in the Bohai Sea coastal zone, Yellow Sea‐East China Sea coastal zone, and South China Sea coastal zone at rates of 0.46 (p < 0.01), 0.18 (p < 0.01), and 0.19 °C/decade, respectively. Spatially, the LSTC decreased in summer and winter with the decrease in latitude and increased in summer and winter with the decrease in longitude. These changes were caused by urbanization, land use changes, and topography. The spatial distribution was more strongly controlled by land than by sea. Meanwhile, the land/sea warming ratio was concentrated within the range of 0–1 and 1–2, and land/sea temperature variation trends commonly followed the same direction. Overall, land/sea surface temperature variations had similar amplitudes. Under three Representative Concentration Pathways (RCPs), the warming rate difference between land and sea in summer is small, but the land warms faster than the sea in winter, resulting in the LSTC decreasing fast in winter. Under RCP4.5 and RCP8.5, the linear trends in LSTC in Bohai Sea coastal zone, Yellow Sea‐East China Sea coastal zone, and South China Sea coastal zone ranged from 0.05 to 0.08 (p < 0.01) and 0.13 to 0.15 °C/decade (p < 0.01), respectively.

Unusual Cross‐Shelf Transport Driven by the Changes of Wind Pattern in a Marginal Sea

“…The wind stress is calculated using the formula of Large and Pond (1982) with some modification from Trenberth et al (1990) (Dittmer, 1977;Schacher et al, 1981) (Supporting Information S1). The ERAI data uses the 4D-Var analysis technique (Li et al, 2016) and its net surface heat flux shows superior performance over other products for the western Pacific region (Song & Yu, 2013;Song et al, 2015;Yao et al, 2019;Zhang et al, 2016). Before the calculation of wind stress, we apply a creeping sea-fill methodology to the ERAI data to correct the land contamination near land-sea boundaries following Kara et al (2007).…”

The Relative Roles of Climate Variation and Human Activities in Vegetation Dynamics in Coastal China from 2000 to 2019

“…In coastal China from 1986 to 2015, the maximum 1-day and maximum 5-day precipitation increased at rates of 0.25 mm y −1 and 0.49 mm y −1 , respectively, although the trend was not significant [14,15]. Besides, the temperature was generally increased with the background of global warming [14,15]. The terrain in the study area is complex and diverse, and there are plains, plateaus, and hills.…”

“…This might enhance plant respiration in nighttime, while inhibit leaf photosynthesis in daytime, reducing accumulation of dry matter. Second, Xu et al [14] and Wang et al [15] reported that the extreme precipitation in coastal China showed an increased trend in recent decades, which may inhibit vegetation growth. More importantly, some studies have shown that in metropolitan areas, the combined effects of extreme climate and negative human activities amplify the effects of both on vegetation [77,78].…”

“…The minimum annual precipitation in north China is 537.7 mm, belonging to temperate and warm temperate climate zones, while the maximum annual precipitation in south China is 1660.7 mm, belonging to subtropical and tropical climate zones. In coastal China from 1986 to 2015, the maximum 1-day and maximum 5-day precipitation increased at rates of 0.25 mm y −1 and 0.49 mm y −1 , respectively, although the trend was not significant [14,15]. Besides, the temperature was generally increased with the background of global warming [14,15].…”

“…The average and extreme temperatures in China's coastal areas show a rising trend, but there is no significant change in precipitation [14]. In the northern coastal areas, drought caused by warming is an important reason for decreasing vegetation coverage [15]. In southern coastal regions, floods caused by extreme precipitation reduce solar radiation and temperature, adversely affecting vegetation [16,17].…”