On the basis of climate change projections, increases in heat-related deaths outweigh reductions in cold-related deaths in the borough of Manhattan, New York, reports a study published in Nature Climate Change. This finding highlights the importance of public health risk management in response to climate warming.

Rising temperatures in urban areas may lead to increased heat-related mortality as well as reduced cold-related mortality, but the net annual effect is, at present, largely uncertain. Most studies on the impacts of future warming on mortality are based on one or a few different climate models and therefore results have not been comparable so far. These analyses also do not usually assess the mortality risk over the whole year. Patrick Kinney and colleagues address both of these shortcomings in estimating future temperature-related mortality. For the first time, they apply downscaled projections from 16 global climate models under two different greenhouse gas emissions scenarios to predict temperature-related deaths on a monthly basis for Manhattan in the 2020s, 2050s and 2080s. The impacts on estimated annual mortality from the different models and scenarios were similar in the 2020s, but began to diverge in the 2050s and differed substantially by the 2080s. The pattern of divergence in mortality mirrors a similar pattern in projected warming. Large increases in the percentage of annual mortality occurred in May and September, when absolute mortality associated with temperature is relatively low at present.

The researchers suggest that adaptation-planning strategies for the public health sector may need to consider promoting vigilance outside the traditional high-heat-risk months of June-August.