The latest population projections from UNDESA  reinforce the trends identified previously, with even higher estimates for global urban populations. The 2012 data used in AR5 projected a global urban population of 4984 million in 2030 and 6252 million in 2050; the 2018 revisions project 5167 million and 6680 million respectively. Particularly noteworthy is the higher projection provided for sub-Saharan Africa's urban population: increasing from 596 million to 666 million in 2030, and from 1069 million to 1258 million in 2050. These figures highlight the continued trend toward larger urban populations, and the particular significance of this in areas which currently have relatively small proportions of their populations living in towns and cities; this is also true in some Small Island States  . The proportion of the global urban population living in megacities  is expected to continue growing slowly  by 2035 . The size and form of these megacities presents particular challenges with climate change impacts, in areas including air quality , flooding , and temperature increase  .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report