Rapid Environmental Change and Rising Vulnerability to the Climate–Water–Health Nexus in Growing and Emerging Megacities

Urbanizing megacities and enhanced climatic extremes are arguably the largest changes taking place across the world today. These anthropogenic and natural forces, respectively, are shaping the world and the impacts on its populations. Growing urban regions face unprecedented challenges due to their large water and energy demands, urban heat island phenomena, degradation of air quality and human health outcomes. At current rates of rapid urbanization across the planet, there will be large scale changes in global land use and cover, hydroclimatic regimes, loss of habitats and biodiversity, and reduced ecosystem functions in the coming decades. The concentration of population in urban centers will also increase the vulnerability to natural disasters, heat waves, and public health burden amid enhanced climate variability. Diseases and health issues of the environment can thrive and expand in an increasingly urbanizing and warmer world.

An estimated billion of the world’s urban residents will soon be living in slums or informal settlements. This is due to rural to urban migration rates accelerating in response to extreme weather events and the impacts of climate change, including frequent severe tropical cyclones and rapid land erosion in coastal areas. This population growth is likely underestimated due to the hidden urbanization associated with sprawl and settled peripheries as the most rapid population growth occurs surrounding the periphery of cities resulting in an expansion of urban footprint. Rapid expansion also is characterized by unplanned development with limited infrastructure, service delivery, and governance capacity resulting in a large portion of the urban dwellers becoming vulnerable to climate-related disasters including acute water scarcity, chronic urban flooding, heat waves, epidemic outbreaks of infectious disease, and infrastructure failure, especially among the urban poor with low-income populations. In Asian megacities with the highest fraction of the urban population living in slums – Dhaka, Bangladesh (40%), Delhi, India (50%), and Jakarta, Indonesia (26%), most slum areas are located in low elevation areas around the city periphery near water bodies. About 70% of slum dwellers have no access to safe sanitation and about 90% live below the poverty line.

In this study, we leverage the availability of an unprecedented amount and continuous availability of satellite datasets to gather information on the large scale changes taking place in growing urban regions across the world to understand and quantify the impacts of land cover change, the evolution of urban heat islands, and enhanced variability of climate extremes. Recent advancements in remote sensing now allow us significant inroads in precise mapping and estimation of environmental conditions that affect water quality and quantity, threats to water resources, vulnerable settlements near pollution hotspots, diarrheal disease outbreaks and transmission risk. With crowd sourced images and field environmental data, taking advantage of high mobile phone and social media penetration in the developing world we can achieve rapid identification and ground validation of urban transmission and health crisis hotspots, water vulnerability, including environmental bottlenecks.

Focusing on the most urbanized state in the union, Rhode Island, and twelve emerging and growing megacities across the world, we aim to address these questions: 1) Can we identify spatio-temporal patterns and extents of water crises, urban flooding, and extreme temperature events? 2) Can we harness the strength of geospatial data and tools to identify and quantify linkages between land use and land cover changes, water insecurity, urban heat island (UHI) phenomena and proximity to harmful environmental features within megacities? 3) What proxy remote sensing or Earth Observations (EO) indicators can be used to scale detailed household surveys to identify poverty variance and vulnerability in informal settlements? and 4) Can we identify areas of extreme vulnerability overlaying these risk attributes with limits of local government response?

In addition to the above science questions, we aim to develop high-resolution geospatial mapping tools to monitor the ‘urban health environment’ in near real-time, where pathogens can persist and thrive or heat islands and heat waves along with acute water shortage and air quality degradation can significantly affect human health. A secondary goal of this project is to use practical digital and science communication and media-content development for encouraging public participation in citizen science endeavors, and disseminate the science of global urbanization patterns, evolving climate extremes and urban heat waves, impacts on water and energy demand, and affect on air quality and urban health parameters.