This article presents lessons from the rich adoption literature for the nascent research on adaptation. Individuals' adoption choices are affected by profit and risk considerations and by credit and biophysical constraints. New technologies spread gradually, reflecting heterogeneity among potential adopters, processes of learning and technological improvement, and policies and institutions. Adaptation is the response of economic agents and societies to major shocks. We distinguish between reactive and proactive adaptation.

Food systems contribute 19%–29% of global anthropogenic greenhouse gas (GHG) emissions, releasing 9,800–16,900 megatonnes of carbon dioxide equivalent (MtCO2e) in 2008. Agricultural production, including indirect emissions associated with land-cover change, contributes 80%–86% of total food system emissions, with significant regional variation. The impacts of global climate change on food systems are expected to be widespread, complex, geographically and temporally variable, and profoundly influenced by socioeconomic conditions.