Large cities account for a significant share of national population and wealth, and exert high pressure on local and regional resources, exacerbating socioenvironmental risks. The replacement of natural landscapes with higher heat capacity materials because of urbanization and anthropogenic waste heat are some of the factors contributing to local climate change caused by the urban heat island (UHI) effect. Because of synergistic effects, local climate change can exacerbate the impacts of global warming in cities. Disentangling the contributions to warming in cities from global and local drivers can help to understand their relative importance and guide local adaptation policies. The canopy UHI intensity is commonly approximated by the difference between temperatures within cities and the surrounding areas. We present a complementary approach that applies the concept of common trends to extract the global contributions to observed warming in cities and to obtain a residual warming trend caused by local and regional factors. Once the effects of global drivers are removed, common features appear in cities’ temperatures in the eastern part of the United States. Most cities experienced higher warming than that attributable to global climate change, and some shared a period of rapid warming during urban sprawl in the mid-20th century in the United States.

中文翻译：

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将城市地区变暖的趋势分解为全球和局部因素

大城市在全国人口和财富中占很大比例，对地方和区域资源造成很大压力，加剧了社会环境风险。由于城市化和人为废热，自然景观被更高热容量的材料替代，是导致城市热岛（UHI）效应引起的局部气候变化的一些因素。由于协同效应，局部气候变化会加剧全球变暖对城市的影响。将全球和当地驱动因素对城市变暖的贡献区分开来，有助于了解它们的相对重要性并指导当地的适应政策。树冠 UHI 强度通常由城市内与周边地区的温差来近似。我们提出了一种补充方法，该方法应用共同趋势的概念来提取全球对观察到的城市变暖的贡献，并获得由局部和区域因素引起的残余变暖趋势。一旦消除了全球驱动因素的影响，美国东部城市的气温就会出现共同特征。大多数城市经历了比全球气候变化更高的变暖，有些城市在 20 世纪中叶的美国城市扩张期间经历了一段快速变暖的时期。美国东部城市的气温出现了共同特征。大多数城市经历了比全球气候变化更高的变暖，有些城市在 20 世纪中叶的美国城市扩张期间经历了一段快速变暖的时期。美国东部城市的气温出现了共同特征。大多数城市经历了比全球气候变化更高的变暖，有些城市在 20 世纪中叶的美国城市扩张期间经历了一段快速变暖的时期。