London School of Hygiene & Tropical Medicine

Published in time for the UN Climate Summit in New York, the study in the Journal of the American Medical Association finds that Milwaukee, Wisconsin and New York City could experience three times as many 32°C days by 2046.

The study, led by the University of Wisconsin-Madison, looks at climate data from a public health perspective and reviews current and projected climate-related health risks. It finds that the risks include more extreme heat waves and intense storms, increased waterborne and infectious disease risks, more chronic health risks related to air pollution, and increased malnutrition.

The study also lays out a number of science-based strategies to reduce emissions of pollutants, through cutting global use of fossil fuels and other strategies, while improving health. These include designing sustainable cities, eating less meat, enacting better carbon-reduction energy policies and promoting active transport such as walking or cycling to work.

Co-author Sir Andy Haines, Professor of Public Health & Primary Care at the London School of Hygiene & Tropical Medicine, said: "Our research suggests that outdated infrastructure in many US cities will pose challenges for adapting to climate change. However, these challenges also provide opportunities to establish more environmentally sustainable cities. We've shown that monetising the health benefits of cutting greenhouse gas emissions, for example from reduced air pollution, could help offset the costs of such policies, and in some cases yield net economic benefit."

In a separate paper published in The Lancet, Professor Haines also discusses the possibility of having to deal with even more serious public health risks later in the century and beyond, as global average temperatures potentially rise to more than 4°C above preindustrial levels by 2100.

He and colleagues warn that continued warming, particularly after 2050, would adversely affect crop yields in most parts of the world, at a time when demand for food will be rising strongly due to projected population growth and economic development.

A high level and rapid rate of global climate change will also severely test biological and social mechanisms for adaptation, the paper highlights, with limits to adaptation becoming increasingly evident. These include emergency preparedness in the face of shortening return periods after catastrophic floods, to saltwater intrusion which could compromise water quality in low lying islands to such an extent that migration might be the only option.

The Lancet paper also describes how the burden of disease due to climate change falls mainly on those living in poverty, and goes on to discuss who should take responsibility for reducing emissions. They write: "Vulnerability to climate change is in many cases inversely related to historical greenhouse gas emissions. Thus, the responsibility for leading policies to reduce these emissions should be shouldered by those nations and commercial interests that have enjoyed the benefits of fossil-fuel-driven development."

Publications

• Patz J A, Frumkin H, Holloway T, Vimont D J, Haines A. Climate Change: Challenges and Opportunities for Global Health. JAMA. doi:10.1001/jama.2014.13186.
• Andy Haines, Kristie L Ebi, Kirk R Smith, Alistair Woodward. Health risks of climate change: act now or pay later. The Lancet. doi:10.1016/S0140-6736(14)61659-7