How much disease could climate change cause
Abstract
Given the clear evidence that many health outcomes are highly sensitive to climate variations, it is inevitable that long-term climate change will have some effect on global population health. Climate change is likely to affect not only health but also many aspects of ecological and social systems, and will be slow and difficult (perhaps impossible) to reverse. Many therefore would judge that there is already sufficient motivation to act, both to mitigate the causes of climate change, and to adapt to its effects. However, such actions would require economic and behavioural changes bringing costs or co-benefits to different sectors of society. Decision-makers, from individual citizens to national governments, have numerous competing claims on their attentions and resources. In order to give a rational basis for prioritizing policies, at the least it is necessary to obtain an approximate measurement of the likely magnitude of the health impacts of climate change. Quantification of health impacts from specific risk factors, performed in a systematic and consistent way using common measures, could provide a powerful mechanism for comparing the impacts of various risk factors and diseases. It would allow us to begin to answer questions such as: on aggregate, are the positive effects of climate change likely to outweigh the negative impacts? How important is climate change compared to other risk factors for global health? How much of the disease burden could be avoided by mitigating climate change? Which specific impacts are likely to be most important and which regions are likely to be most affected? Caution is required in carrying out and presenting such assessments. Richard Peto, in his foreword to the first global burden of disease study (1), echoed the economist John Kenneth Galbraith in suggesting that epidemiologists fall into two classes: those who cannot predict the future, and those who know they cannot predict the future. Given the importance of natural climate variability and the potential for societal and individual factors to mediate the potential effects of climate change, only approximate indications of likely impacts can be expected. However, it is important to make such estimates available to policymakers, along with a realistic representation of the associated uncertainty; or remain in the current unsatisfactory condition of introducing a potentially important and irreversible health hazard throughout the globe, without any quantitative risk assessment.