COS 69-2 - Satellite view of urban food-energy-water nexus under climate extremes

Abstract: The urban environment is a multifaceted system with various sub-systems that interact with each other in a complex manner. In the past several decades, the world has experienced major urban expansion, and the urbanization trend is expected to continue in the next few decades, especially in Asia and Africa. Urbanization has profound impacts on energy, water, and agriculture from local to regional and even global scales due to high consumption of resources in urban areas. The objectives of this study are to better understand the synergy and trade-off of food-energy-water response to climate change over urban clusters. Here we use big Earth data that integrating regional network of metrological/hydrological measurements, census data, multiple visible/near infrared and thermal infrared satellite data to estimate multiple scale structure of urban clusters, and to assess effects of urban heat stress on food-energy-water nexus at local and regional scales.
Urbanization influences water demand in several sectors including agriculture energy supply in a complex and nexus way. Meanwhile, climate change and extremes are also expected to have complex and interactive impacts on food, energy, water over urban clusters. The impact of climate change on water, energy, and food will be compounded together with urbanization because the influences of urbanization and climate change could be cumulative and the combined effects could be much more severe. Urbanization, together with temperature and precipitation change due to changing climate, will increase the challenge of water sustainability in terms of growing water, energy, and food demand. The synergy and trade-off of food-energy-water response to urbanization and climate change are critical for regional sustainability. In the case study areas, strong spatial connection and internal expansion were found in major urban clusters in past 30 years, and was accelerated in past 10 years. Cities and towns were more connected with roads and commercial corridors, while wildland and urban greens became more isolated as patches among built-up areas. Meanwhile, the increasing trend of nighttime heatwaves in urban areas than rural areas in both tropical and temperate climates is largely due to urbanization, which amplifies heatwaves with urban heat island (UHI) effects. Increased UHI intensity amplifies the effects of nighttime heatwaves in urban clusters, while urban green increase can attenuate the UHI effect particularly in arid climate. The cooling effects of urban greens tend to be weakened as their patches became smaller and isolated, and over dominated by urban surfaces.