Recognition that human health is affected by a wide range of ecological disruptions consequent upon climate change is a recent development, reflecting the breadth and sophistication of modern scientific knowledge. Global climate change affects human health via pathways of varying complexity, scale, and directness and with different timing. Similarly, impacts vary geographically due to both environment and topography and the local population’s vulnerability. This is no surprise since climate change alters an extensive range of natural ecological and physical systems integral to earth’s life support system.