A multi-faceted, pan-Mediterranean assessment of urban land change for the evaluation of interconnected climate risks

More responsive to climate change than most other parts of the planet, future warming on the Mediterranean coast is expected to increase 25% faster than the global average—40% faster in summer. Climate change poses a series of inter-connected risks to the region and is poised to substantially increase biodiversity loss, food insecurity, and flooding in human settlements over the next decades. However, each of these risks is amplified by another major transition occurring in the region—urbanization. The Mediterranean and North Africa have quadrupled in population and doubled in urbanization rate since 1960, and also host nearly 1/3 of all international tourists. Forty percent of the coastline is already covered in manmade structures with the pressures of urban land change predicted to escalate, particularly in secondary cities that still have unmet infrastructure deficits.

As a hotspot of climate risk, where coastal urbanization increases the vulnerability of land systems to climate change impacts, there is an urgent need to better understand the where, how, and when of urban LCLUC surrounding the Mediterranean Sea as a step toward anticipating future impacts. Assessments of urban development across the entire coastal zone are still lacking, and in particular, some of the more vulnerable and resource-limited countries in the region have been insufficiently studied. A multi-faceted, pan-Mediterranean assessment of urban change is needed to understand how urban growth interacts with the interconnected risks in the region.

The proposed research aims to fill this knowledge gap by focusing on interactions between urbanization hotspots and climate change risks. Our main objectives are to: (1) to characterize, map, and quantify urban LCLUC changes (land + built environment) on the coast of the Mediterranean, (2) to assess how these land changes have impacted multiple risks in the region (risks to biodiversity, food security, and flooding), and (3) to document how or if these risks have in turn shaped urban development, leading to different patterns of urban growth and change. This project uses multi-scale, multi-sensor remote sensing data and state-of-the-science methods to answer four fundamental science questions:

1. How are urban coastal settlements along the Mediterranean Sea changing? What land covers and land uses have been subsumed by urban coastal development?
2. Urban land change is multi-dimensional. To what extent have urban changes consisted of urban expansion, urban intensification, vertical growth, or infrastructure development?
3. How have urban changes (from (1) and (2)), interacted with or amplified the risks of biodiversity loss, flooding, and risks to food security in the region through habitat conversion, agricultural land encroachment, or expansion/intensification in flood zones? Where are the hotspots of multiple risk from urban LCLUC?
4. What are the drivers of the different patterns of urban LCLUC across the region? To what extent have the risks in (3) influenced development patterns on the Mediterranean coast?

This proposal is novel in its characterization of multiple types of urban LCLUC. In addition to urban expansion, we propose to apply multi-sensor land imaging (using NASA’s Black Marble, Landsat-8, and Sentinel-1 C band) to map urban intensification, vertical growth, and infrastructural investment, improving linkages between the diversity of development patterns occurring on the Mediterranean coast and the risks they shape. We will also utilize new remote sensing techniques (continuous settlement monitoring, sub-seasonal nightlights time series classification, and vertical change assessment) that have not yet been applied routinely across the Mediterranean region. This project will identify hotspots of urbanization-climate compound risk and contribute to ongoing GOFC-GOLD MedRIN efforts, exploring the mitigation of risk through spatial planning and active management.