Karen Seto

Professor of geography and urbanization science at the Yale School of the Environment, Seto trained in Boston and first studied the Pearl River Delta in China, where remote sensing let her measure urban expansion year by year. Her 2011 meta-analysis of global urban land expansion and her 2012 projection, which estimated that urban land could triple between 2000 and 2030, are the data the climate community has used ever since.

Her most uncomfortable finding is that cities grow over the best farmland, because cities were born where the land was fertile, and that this century's expansion threatens food production and carbon sinks at the same time. She coordinated the chapter on human settlements and infrastructure of the IPCC's fifth report (2014) and the urban mitigation chapter of the sixth (2022), which established that urban form, compact, mixed and connected, is one of the largest remaining levers for cutting emissions.

A member of the US National Academy of Sciences and the American Academy of Arts and Sciences, Seto has turned urbanization science into a field with global data, and her message for cities is that the infrastructure built now locks in the emissions of the coming decades.