2018; Bassolas et al., 2019). Key or critical infrastructure provides much of the material basis of cities and settlements, as well as the mechanisms for enabling flows of people, goods, data, waste, energy  and capital, between urban regions and rural areas . An overview of this process of 'planetary' urbanisation is provided in Box 6.1. The balance of accumulated scientific knowledge on climate risks, impact and adaptation has been generated from studies in large and medium-sized cities of 1 million or more. While these larger cities continue to grow rapidly , settlements of more than 5 million people contain less than a quarter of the world's urban population, and more than half of the world's urban residents live in settlements of 1 million or less . There is a key gap in knowledge, especially concerning urban enabling environments and how smaller settlements can be supported to accelerate equitable and sustainable adaptation in the face of financial and governance constraints .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report