Urbanization, a major driver of global change, profoundly impacts our physical and social world, for example, altering carbon cycling and climate. Understanding these consequences for better scientific insights and effective decision-making unarguably requires accurate information on urban extent and its spatial distributions. With support from NASA Land Cover and Land Use Change (LCLUC) Program, this webinar presented the research methods and findings from the project, Understanding and Simulating Global Urban Expansion in the Context of Climate Change.

In the decade of the 2000s, urbanization occurred at an astounding rate, especially in Asia, with the extensive development of numerous mega cities. Understanding of urban change becomes more imperative not only as the world becomes more urban than rural, but also as more urban dwellers live in conditions adversely impacted by the mega urbanization that can be observed and monitored with satellite remote sensing across administrative boundaries. Amongst the mega cities of the world, Beijing has undergone transformative changes with an extreme urbanization rate.

The specific objective of this project is to understand the role that improved transportation routes especially new roads and connectivity have on both urban and rural land-cover/land-use. The recent webinar presented some of the preliminary results of this project and looked at changes that have taken place within the East-West Economic Corridor (EWEC) in Vietnam.

The United States is home to 5% of the world’s population and 30% of the world’s automobiles, emitting 45% of global transportation CO2 emissions (DeCicco et al. 2006). In 2012, automobile emissions were 28% of total US fossil fuel CO2 emissions and accounted for almost half of the growth in total US emissions since 1990 (US EPA 2014). Despite being a substantial component of US emissions, on-road CO2 remains poorly quantified at sub-state and urban scales (Gately et al. 2013).

This interdisciplinary project examines how urban infrastructure and vegetation (land cover) is distributed in and around sub-tropical desert cities and how this affects both the local and regional climate. Five regions were chosen-Las Vegas, USA; Beer Sheva, Israel; Jodhpur, India; Kharga, Egypt; Hotan/Hetian, China-to allow for a comprehensive analysis.

Urban land covers alter the rhythms of regional climate on many time scales. Urban areas locally alter climate through changing the brightness and the dryness of urban surfaces, reducing wind speeds within cities, and increasing the concentration of air pollutants over cities. These changes interact to increase temperatures within and over cities relative to nearby rural areas in a phenomenon known as the urban heat island (UHI) effect.

Impervious surfaces, mainly artificial structures and roads, cover less than 1% of the world’s land surface (1.3% over USA). Regardless of the relatively small coverage, impervious surfaces have a significant impact on the environment at scale from the local to the global. They are the main source of the urban heat island effect, and affect not only the energy balance, but also hydrology and carbon cycling, and both land and aquatic ecosystem services. In the last several decades, the pace of converting natural land surface to impervious surfaces has increased.

The objectives of the study are to: (1) map and quantify land cover and land use change (LCLUC) within an extensive study area in Ghana from 2000 to 2010, (2) understand the regional impacts of LCLUC associated with rural-to-urban migration in driving these changes, and (3) assess LCULC and its effect on demographic and quality of life factors during this time period.

US cities are home to more than 50% of the population and this is where climate change will be felt the most. Urban communities will be interested to know how cities interact with climate and the scientific community is interested to include the urban ecosystem functions in climate models. Scientists at NASA use data fusion from Landsat and MODIS to characterize US urbanization and model its impact on surface climate. For cities built within forests, daytime urban land surface temperature (LST) is found to be higher than that of vegetated lands.

Urbanization is among the most rapid and visible types of landscape transformations with climatic, hydrological, biophysical and ecological impacts on the environment. To quantify the impacts of such transformation urban areas should be characterized in terms of both the density of impervious areas and vegetated cover. In this project we use observations from Landsat and NPOESS VIIRS Day/Night Band to derive a consistent, robust, scalable characterization of the urbanization at sub-pixel resolutions.