Global Urbanization and its Implications in Environmental Sustainability

Driven by economic development, population growth, and public policy, human induced land use and land cover changes (LCLUCs) have profound feedbacks on human activities and their interactions with natural systems. Urbanization, one of the major LCLUCs, is becoming increasingly important in global environmental changes, such as urban heat island (UHI) growth and vegetation phenology change. In the past several decades, the world has experienced fast urbanization, and this trend is expected to continue for decades to come. Better scientific insights and effective decision-making for a sustainable environment unarguably require reliable science-based information on spatiotemporal patterns of urbanization and their environmental impacts.

In this study, we developed a globally consistent 20-year urban map series to evaluate the time-reactive nature of global urbanization from the nighttime lights remote sensing data, and projected future urban expansion in the 21^st century by employing an integrated modeling framework. We then extended the modeling capability of building energy use in the Global Change Assessment Model with consideration of urban heat island (UHI) effects by coupling the remote sensing based urbanization modeling and explored the impacts of UHI on building energy use. We also investigated the response of vegetation phenology, which affects both ecosystem services and human health, to urbanization by using an improved phenology detection algorithm. The derived spatiotemporal information on historical and potential future urbanization and its implications will be of great value in improving our environmental sustainability, especially when considered together with other factors such as climate variability and change.