全球气候变化背景下基于土地利用的人类活动对城市热环境变化归因分析——以京津冀城市群为例

近年来全球气候变化已经影响到人类生活的所有地区,气候系统变化的规模和现状是数千年来前所未有的。与此同时,中国城镇化进程显著加快,尤其以城市建设用地扩张主导的土地城镇化最为突出,导致城市热环境脆弱性加剧。已有研究探索了特定类型土地利用变化对于城市热环境的影响,但忽视了全球气候变化背景下自然气候和人类活动共同作用城市热环境变化的双重过程。因此,本研究提出一种基于土地利用类型的城市热环境变化贡献度算法,旨在厘清自然气候（表征为土地利用平均温度变化）和人类活动（表征为土地利用类型转变）对于区域热环境变化的单独贡献。本研究使用中分辨率成像光谱仪（Moderate-Resolution Imaging Spectroradiometer,MODIS）地表温度及发射率数据,定量计算2005—2020年四季和昼夜京津冀城市群各城市土地利用类型平均温度和面积变化对于城市热环境变化的分别贡献。该算法计算各城市四季和昼夜地表温度变化与MODIS LST产品误差在1 K以内。2005—2020年各城市地表平均温度大多数呈增长态势,其中冬季白天增温幅度最高。耕地、城市建设用地和农村居民点对城市热环境变化的贡献度较其他土地利用类型突出。京津冀城市群中各城市人类活动对城市热环境变化的单位贡献强度远高于自然气候（4.03~648.07倍）,而人类活动的贡献总量（-0.25~0.92 K）低于自然气候（-2.40~6.50 K）。研究结果对于京津冀城市群空间协同发展和适应及减缓气候变化等具有重要的科学意义和实践价值。

Quantifying the contribution of land use change based on the effects of global climate change and human activities on urban thermal environment in the Beijing-Tianjin-Hebei urban agglomeration

In recent years, global climate change has already affected every inhabited region across the globe. The scale of changes across the climate system as a whole and the present state of many aspects of the climate system are unprecedented over thousands of years. At the same time, the process of urbanization in China has accelerated significantly. The urbanization with expansion of urban construction land is the most prominent, which directly leads to an increase in the vulnerability of urban thermal environment. Previous studies have explored the impacts of specific land use changes on the urban thermal environment, but have neglected the dual process of natural climate and human activities in urban thermal environment changes under the background of global climate change. Therefore, this study proposes a contribution degree algorithm for land-use-based urban thermal environment change, which aims to clarify the individual impact of natural climate (characterized by land use average temperature change) and human activities (characterized by land use type transition) on regional thermal environment changes. This study uses Moderate-Resolution Imaging Spectroradiometer (MODIS) land surface temperature and emissivity data to calculate the individual contribution of the average land surface temperature and area changes of the urban land use types to the thermal environment changes between 2005 and 2020 in the Beijing-Tianjin-Hebei (BTH) urban agglomeration. The difference between the seasonal and day-night land surface temperature changes of each city calculated by the algorithm and the MODIS LST product is within 1 K. Between 2005 and 2020, the average land surface temperature in most cities has shown an increasing trend, with the highest increase in winter day. Cultivated land, urban construction land and rural residential areas contribute more to urban thermal environment changes than other land use types. In the BTH urban agglomeration, the influence intensity per unit area of human activities on urban thermal environment changes is much higher than that of natural climate (4.03-648.07 times), while the total contribution of human activities (-0.25-0.92 K) is lower than that of natural climate (-2.40-6.50 K). The results have important scientific significance and practical value for the coordinated development of space in the BTH urban agglomeration as well as the adaptation and mitigation of climate change.