Power demand from air conditioners and other cooling already exceeds that from data centers and could double or triple by mid-century. As temperatures rise, cities expand and incomes increase, hundreds of millions of households are expected to gain access to air-conditioning over the coming decades. While the trajectory has been anticipated for years, policymakers and planners are now focusing more on the challenge, from the scale of additional power needed to the impact of heat waves on peak demand. Managing cooling demand will require greater investment in batteries, demand-response mechanisms, grid flexibility and smarter electricity systems.