This document provides an overview of climate change and human health. It discusses the international environment agenda related to climate change since the 1970s. It also reviews evidence of past climate changes and projections of future temperature increases. The document then examines how climate change can impact human health through changes in temperature extremes, precipitation, drought, and tropical cyclones. It reviews evidence of impacts of recent heat waves. The document discusses challenges in assessing the relationship between climate and health and detecting the effects of climate change. It also outlines how climate change may differ from other environmental health risk assessments given its scenario-based nature and focus on future time periods.