Climate change and human health: recognising the really inconvenient truth.

he United Nations Climate Change Conference in Copen-hagen (7–18 December) will soon be behind us. Climate change, however, continues to progress more rapidly and disruptively than climate scientists foreshadowed only 5 years ago. Recent peer-reviewed reports of climate change processes and impacts show, among other effects, an increased rate of greenhouse gas accumulation in the lower atmosphere, and an accelerating sea level rise. This has prompted a worrying reappraisal of where we might now be heading. Earlier this decade, there were hopes of limiting the global temperature increase to about 2° C. There is now growing scientific recognition that we need to prepare for an even more disrupted world with temperature rises of up to 3–4° C. Most political institutions have short-term priorities. These impede the urgent, enlightened and unselfish collective action needed to respond to this unprecedented global environmental challenge. 3,4 Despite the rapid maturation of climate change science and the wonders of global sensing technology and electronic connectivity, we collectively fail to understand the full extent of the risks we face. Something fundamental is missing. Preoccupation with the technical details of climate change science, and with economic costs, property protection and the politics of shared responsibility, has overshadowed full appreciation of the consequences for human health and survival. Despite the growing recognition of the risks posed by climate change to social and economic wellbeing, the risks to human health are mostly viewed as regrettable, and hopefully tolerable, collateral damage. This view is very naïve. It fails to recognise the profound significance of the risks posed to the biology and health of plant and animal species everywhere, including our species. Christmas joys aside, this situation signals a Red Alert. Climate change is weakening Earth' s life-support systems, and, if not reversed, portends a disastrous outcome. This is no longer a matter of speculation or theoretical modelling. The number of people affected annually by heatwaves and other extreme weather events has risen in several countries over recent decades. For example, the average annual number of excess deaths associated with heatwaves has increased markedly over the past two decades in Hungary, commensurate with a threefold increase in the average annual frequency of heatwaves. 5 Food yields have recently decreased in some regions, including parts of Asia, southern Africa and the eastern Sahelian region of Africa, in association with a range of environmental stresses that include warming, drying and severe flooding. 6 …