Quantifying and Mapping the Human Footprint Across Earth's Coastal Areas

Connecting marine and terrestrial environments, coastal ecosystems are diverse, supporting rich biodiversity and providing a wide range of ecosystem services. Coastal ecosystems are also highly vulnerable to marine and land-based stressors due to human modification and global climate change. Coastal regions are home to hundreds of millions of people around the planet and the majority of the world’s countries have coastal areas. To help effectively address the multiple threats to coastal ecosystems and prioritise conservation action, there is an urgent need for systematic quantification and mapping of cumulative coastal stressors that is comparable globally and includes both marine and terrestrial-based stressors. To address this gap, we mapped human stressors at the global extent and quantified the human footprint across each of Earth’s coastal areas, incorporating key terrestrial and marine stressors. We found that almost all coastal grid cells (97%) across the globe had at least one stressor present. Human population density strongly predicted the variability in the coastal human footprint, with the coasts of Belgium, Monaco, Singapore, and Israel’s Mediterranean Sea showing the highest coastal footprint score globally. The lowest coastal footprint values were found in Antarctica and the Arctic. We identified 160 remaining “coastal wilderness” areas outside the polar areas. Amongst these, only 38 coastal wilderness areas globally are fully protected, while 63 coastal wilderness areas are currently entirely unprotected. We highlight the need to create platforms targeting coastal environments to help address the gaps in coastal area conservation and management around the world.