Briefing Note 8. Ecosystem-based adaptation (EbA) is a strategy for adapting to the adverse impacts of climate change by harnessing nature and the services it can provide. This strategy is crucial for cities and peri-urban areas, threatened by a multitude of climate hazards and home to more than half the human population as of 2018. Despite some outmigration from the largest cities during the COVID-19 pandemic, urbanization will continue, and by 2035, 62.5 percent of the world’s population is expected to reside in urban areas. However, given the need to retrofit, replace and upgrade deteriorating urban infrastructure, and to meet the challenges of climate change, including the urban heat island effect, droughts and more intense flooding, many experts and policymakers see in these demands an opportunity to reinvent cities as greener, less prone to pandemics, and more liveable.