Will climate change worsen your health?

8% of deaths in are due to ambient temperatures, and global warming represents additional threat for health. we expect more frequent, intense and persistent heat waves during the present century, it not clear whether the number of attributable will also increase. Here I discuss why the role of early adaptation to temperature rise is a research topic in science and policy-making, and how these eventual acclimatization processes depend on a myriad of non-climate factors such air quality in cities, social differences within and between societies, demographic changes or the evolution of the economy.

Will climate change worsen your health?

Research article
Nearly 8% of deaths in Europe are due to ambient temperatures, and global warming represents an additional threat for public health. Despite the fact that we expect more frequent, intense and persistent heat waves during the present century, it is actually not clear whether the number of attributable deaths will also increase. Here I discuss why the role of early adaptation to temperature rise is a major ongoing research topic in science and policy-making, and how these eventual acclimatization processes depend on a myriad of non-climate factors such as the air quality in cities, social differences within and between societies, demographic changes or the evolution of the economy.

Temperature and human mortality
The environment is continuously and silently reshaping human's behavior and physiological response. The long-term exposure of human populations to environmental conditions and natural hazards determines the risks that are associated with the way we live our daily life and we design the structure of our societies.
Urban and coastal settlements exemplify the constant ght between the periodic occurrence of natural phenomena and the transformation of the natural environment to accommodate human activities. Sea storms eroding the front line or ash oods causing landslides for instance represent permanent challenges for the security of people and infrastructures.
https://www.climanosco.org/published_article/will-climate-change-worsen-your-health/ 2/9 An important example of the risks associated with the interaction between humans and the environment is nowadays the exposure to ambient temperatures. In regions such as Europe, average summer temperatures can be up to a few tens of degrees Celsius warmer than in winter. On top of that, temperatures experienced during the most extreme heat waves and cold spells of the year can in turn exceed by about ten degrees or more these average summer or winter conditions, respectively.
The wide range of temperatures to which people are exposed, as well as the temperature variations from one day to the following, represent a major challenge for human well-being. There is indeed a temperature point at which human mortality tends to be at its minimum value, the so-called comfort or optimum temperature, which typically occurs in mid-latitude countries twice per year around late spring and early fall [N Christidis et al., 2010]. This comfort temperature de nes two separate periods of heat-and cold-related mortality in summer and in autumn, winter and spring, respectively, with rising daily mortality counts as temperatures get warmer or colder [A Gasparrini et al., 2015].
The value of the comfort temperature is actually different in each country, region or city, but the relationship between temperature and mortality is similar everywhere, generally characterized by an asymmetric U-shape with minimum mortality for the temperate days, and maximum for the central part of the winter and summer seasons [FC Curriero et al., 2002].
The range of temperatures to which people are exposed characterize the kind of habits and activities that societies and individuals do. This also affects the type of preventive Climate change and early adaptation https://www.climanosco.org/published_article/will-climate-change-worsen-your-health/ 3/9 Global warming is however modifying these relationships that resulted from the longterm adaptation process of human populations over periods of several decades or centuries [H Achebak et al., Under Revision]. The release of increasing amounts of greenhouse gases to the atmosphere is progressively warming the atmosphere, and this is rede ning the range of temperatures to which people are exposed [IPCC, 2013]. But interestingly, the 2003 heat wave also triggered the design and implementation of a wave of national and regional action plans against the negative effects of heat waves [IPCC, 2014]. It is generally believed that these adaptation measures are starting to reduce the additional health burden caused by warmer summer temperatures, but no systematic analysis is available yet. This potential bene cial effect would however depend on the socioeconomic and demographic situation of each society, and it is reasonable to expect that poorer countries will have more problems to deal with the new challenges associated with climate change.
The picture for winter mortality is even more interesting and uncertain, because it is not even clear if and to what extent rising temperatures are contributing to reduce the death toll due to cold temperatures. A major factor explaining this uncertainty is that many of the deaths in winter are due to in uenza and other respiratory viruses, and not directly to cold temperatures themselves, and therefore temperature rise might not contribute to the decrease in winter mortality if the impact of these diseases is not similarly reduced.
https://www.climanosco.org/published_article/will-climate-change-worsen-your-health/ 4/9 The 2008 recession and life expectancy Human health is not only affected by temperatures and climate change, but also by a myriad of factors that exacerbate some existing health threats, such as urban air pollution, pre-existing or chronic diseases, low income, fuel poverty or the gender gap, https://www.climanosco.org/published_article/will-climate-change-worsen-your-health/ 5/9 Instead, other factors have a nearly immediate effect on human health. For example, recessions reduce industrial activity, and therefore the exposure to atmospheric pollutants mainly in urban environments. Moreover, the general reduction in available household income and the increase in social inequality generate side effects such as the reduction in occupational and traf c accidents [RB Noland and Y Zhou, 2017]

Summary
The description and understanding of the environmental determinants of human health is a complex issue. Climate change can be quanti ed by means of climate models, but the impact that these changes will have on human societies is hard to quantify and therefore remains highly uncertain. The future well-being of individual citizens cannot be assessed yet because the observed warming has been small, and we do not fully understand if and to which extent we are adapting to a changing world and climate.
In addition, there are so many non-climate factors that interfere in the way we are affected by climate that it is dif cult to separate their relative contributions. Among those, the demographic revolution that many societies have been experiencing during the last decades, with a continuous and sustained rise in life expectancy, de ne a complex network of interplaying factors affecting human health. Despite these adversities, it is our job to join efforts from different disciplines, such as climate, health, demography and economy, to de ne cross-disciplinary collaborations to better understand these interactions.