Global temperatures have increased at an unprecedented pace over the past 40 years, and significant further warming could occur, depending on our ability to restrain greenhouse gas emissions. This chapter finds that increases in temperature have uneven macroeconomic effects, with adverse consequences concentrated in countries with relatively hot climates, such as most low-income countries. In these countries, a rise in temperature lowers per capita output, in both the short and medium term. Sound domestic policies and development alongside investment in adaptation strategies could help to some extent, but given the constraints faced by low-income countries, the international community must play a key role in supporting these countries’ efforts to cope with climate change.