Health risks, present and future, from global climate change.

There is now no serious scientific debate: human actions are changing the world’s climate, and are set to do so at an increasing rate in coming decades. 2 Urgent action is now required to reduce emissions of carbon dioxide (the dominant long acting greenhouse gas), if global temperature rises are not to exceed 2°C—the International Energy Authority warns that “the door to 2°C is closing.” Indeed, emissions must be hugely curtailed within just two decades, and then zero net emissions achieved by later this century, assisted by increased biosequestration of carbon dioxide from the atmosphere. However, emissions continue to rise, having increased by 49% since 1990 and by an accelerated annual rate of 5.9% in 2010. As warming proceeds, the frequency and intensity of extreme weather events such as heatwaves, cyclones, floods, storm surges, heavy precipitation, and droughts are forecast to increase substantially. Many such changes are already becoming apparent worldwide. ⇓ Themeteorological (and resultant economic) impacts of climate change have been a major focus of public discussion, but associated threats to human health and survival have received much less attention. This may reflect, in part, a limited appreciation of the fundamental dependence of human population health on the natural environment’s so called life support systems. People may also have a false sense of security engendered by the seeming invincibility of modern urban environments to inclement weather. But while industrialised urban societies may be complacent, many poor and vulnerable populations are already experiencing the health impacts of human induced climate change, whether through under-nutrition, diarrhoeal disease, extreme weather events, or sea level rise. However, as the tempo of extreme weather events increases, such impacts will be felt worldwide as the environmental and social foundations of population health—food and water supplies, natural constraints on infectious diseases, natural barriers against environmental disasters, and the stability and cohesion of societies—are disrupted and weakened. Risks to human health