Will a Reduction in Cold-Related Deaths Offset the Increase in Heat-Related Deaths Globally Under Climate Change?

Check out this answer from Consensus:

Overall, while reductions in cold-related deaths are expected due to climate change, these reductions are generally not sufficient to offset the increase in heat-related deaths globally. The net effect on temperature-related mortality varies by region, with some areas experiencing a net increase in deaths and others potentially seeing a decrease. Adaptation strategies and urban heat island effects play significant roles in shaping these outcomes. Effective public health interventions and climate adaptation measures are crucial to mitigate the adverse impacts of climate change on temperature-related mortality.

The impact of climate change on temperature-related mortality is a critical area of research, as both heat- and cold-related deaths are influenced by changing global temperatures. This synthesis examines whether a reduction in cold-related deaths will offset the increase in heat-related deaths globally under climate change.

Key Insights

• Reduction in Cold-Related Deaths vs. Increase in Heat-Related Deaths:
  • In the UK and Australia, cold-related mortality is projected to decrease significantly, but this reduction will not fully offset the increase in heat-related mortality by the 2080s1.
  • In China, the reduction in cold-related deaths is expected to be offset by an increase in heat-related deaths, with a net increase in temperature-related mortality under high-emission scenarios2.
  • In the U.S., the reduction in cold-related deaths may slightly exceed the increase in heat-related deaths for global warming below 3°C. However, above 3°C, the increase in heat-related deaths is likely to outweigh the reduction in cold-related deaths, especially in northern cities5.
• Regional Variations:
  • In ten large U.S. metropolitan areas, eight are projected to experience a net increase in temperature-related deaths under a high-emission scenario, with only two areas potentially seeing a net decrease3.
  • In Beijing, the increase in heat-related cardiovascular disease (CVD) deaths is projected to be higher than the decrease in cold-related CVD deaths, leading to an overall increase in temperature-related CVD mortality4.
• Impact of Urban Heat Islands (UHIs):
  • In China, urban heat islands exacerbate the negative effects of climate change, leading to additional heat-related deaths, particularly in densely populated urban areas2.
• Role of Adaptation:
  • Adaptation measures can influence the balance between heat- and cold-related deaths. In the U.S., southern cities are better adapted to heat, resulting in a net reduction in temperature-related mortality, while northern cities face higher heat-related mortality due to less adaptation5.
  • In Beijing, adaptation to climate change may paradoxically increase temperature-related CVD deaths, as the increase in cold-related deaths due to adaptation measures may surpass the decrease in heat-related deaths4.

Will a reduction in cold-related deaths offset the increase in heat-related deaths globally under climate change?

Tarik Benmarhnia has answered Unlikely

An expert from University of California, San Diego in Environmental Science, Global Health

A quick answer would be not really overall but it depends where.. 

In most locations cold-related deaths will not offset the increase in heat-related deaths but in few places it may be the case depending on climate simulations that are sued. 

I encourage to have a look at this paper on Figure 3 : 

https://www.sciencedirect.com/science/article/pii/S2542519617301560

Will a reduction in cold-related deaths offset the increase in heat-related deaths globally under climate change?

Scott Sheridan has answered Unlikely

An expert from Kent State University in Bioclimatology, Climatology

This is actually quite a difficult question to answer, since, simply put, how heat affects us and how cold affects us are not polar opposites. Nearly all research worldwide shows a “V” shape pattern between temperature and mortality – that is, there is a moderate temperature that is the “minimum mortality temperature” and more people die above as well as below that temperature on average. For heat, deaths are mostly acute – we see immediate impacts from increases in deaths due to heat stroke, cardiovascular problems, and many other causes. For cold, deaths tend to be delayed. Aside from causes such as hypothermia – which is a really small percentage of overall cold-related mortality, typically the biggest increases in mortality are seen several days after very cold weather, and can be related to increased respiratory infections among other causes. Thus, we study the two extremes somewhat differently.

So, to the future. For one thing, in most temperate places, far more people die of the cold than the heat, and because of influenza and other infectious diseases, typically around 10% more people die in winter than summer. Most studies (a few of which are shown below) show that heat related mortality will increase, and winter will decrease, but they disagree on the offset. Some show a greater reduction in cold deaths, some a greater increase in heat deaths. And above all, there’s much uncertainty.

Why the uncertainty? Much research into how we deal with extreme temperature has identified a fe things that go beyond climate change itself that are important. One is demographic change. The world, especially the developed world, is rapidly aging. Older persons are more vulnerable than younger persons to the impacts of extreme temperature events. As a result, there will likely be many more vulnerable people in the decades ahead; in one study (Hajat et al. 2013) the demographic changes nearly offset the benefits of lower cold exposure in terms of cold-related mortality. Another big unknown is adaptation. In the developed world, most studies have shown a decrease in vulnerability to heat events over recent decades (Sheridan and Allen 2018), which is attributed to greater awareness, air-conditioning, and health care. How will this play out into the future? We’ll certainly adapt somewhat to warmer conditions, but tactics such as air conditioning have their limits. There’s really no model for adaptation that’s universally accepted in the literature.

Ultimately, the answer is hard to discern since studies, due to the uncertainty of adaptation measures, display varied results. What is certain is that with demographic changes, the potential is there for much greater vulnerability as time moves on, due to rapidly increasing numbers of those most vulnerable.

References:

Hajat, Shakoor, et al. “Climate change effects on human health: projections of temperature-related mortality for the UK during the 2020s, 2050s and 2080s.” J Epidemiol Community Health 68.7 (2014): 641-648.

Huynen, Maud MTE, and Pim Martens. “Climate change effects on heat-and cold-related mortality in the Netherlands: a scenario-based integrated environmental health impact assessment.” International journal of environmental research and public health 12.10 (2015): 13295-13320.

Li, Tiantian, Radley M. Horton, and Patrick L. Kinney. “Projections of seasonal patterns in temperature-related deaths for Manhattan, New York.” Nature climate change 3.8 (2013): 717.

Sheridan, Scott C., and Michael J. Allen. “Temporal trends in human vulnerability to excessive heat.” Environmental Research Letters 13.4 (2018): 043001.

Will a reduction in cold-related deaths offset the increase in heat-related deaths globally under climate change?

xiaopan Li has answered Extremely Unlikely

An expert from Center for Disease Control and Prevention in Epidemiology, Lung Cancer

For this topic, first of all, I think the way to ask questions is wrong, because it sets temperature and death as a linear relationship, but in reality it is not a reciprocal problem, high temperature leads to excess death, and low temperature can also lead to excess death. Secondly, in the world, or in a limited area, the health problems caused by low temperatures are often more serious than those of high temperatures. Finally, the correlation between temperature and death is an interval problem. If we disregard the value of things and talk about the nature of things, they often produce fallacies.

Will a reduction in cold-related deaths offset the increase in heat-related deaths globally under climate change?

Aleš Urban has answered Unlikely

An expert from Czech Academy of Sciences in Biometeorology, Bioclimatology, Climatology

A recent study by Gasparrini et al. [1] tried to answer our question, taking into account delayed effects of low temperature on mortality (please see the answer by Scott Sheridan). The authors used data from 451 locations in 23 countries across nine regions of the world. They estimated temperature-mortality relationships in each location under recent climate and then projected future excess mortality for cold and heat (corresponding to days with temperatures lower or higher than the so called “minimum mortality temperature”) under four climate change scenarios [2] and calculated the net change of temperature-related excess mortality.

From the global point of view, the results indicate that, under the highest-emission scenario, the increase in excess mortality due to hotter summers will considerably overcome the decrease in cold-related mortality due to milder winters. However, important geographical differences were found. While populations living in warmer (and often relatively poorer) regions (southeast Asia, Central and South America, Southern Europe) are expected to experience net increases in temperature-related mortality due to an increase in heat-related impacts, populations living in temperate climate (Northern Europe, east Asia) may experience only small increase or even slight decreases in the net effect even under the highest-emission scenario due to less intense warming and large decrease of cold-related impacts. The health risks for population living in warmer and poorer regions may be may be substantially reduced, however, under scenarios involving the mitigation strategies.

Though, findings of studies projecting heat and cold-related mortality under future climate need to be interpreted with a caution as they do not assume any changes in the temperature-mortality relationship due to adaptation and demographic changes, which is very unlikely as described by Scott Sheridan. The reported results should therefore be understood as potential impacts of climate change if no adaption takes place. In addition, while the effect of extreme heat on mortality is direct and quite well understood, the effect of cold temperatures on mortality in winter is rather indirect and other factors than air temperature may play an important role in winter mortality. In particular, epidemics of influenza and/or acute respiratory infections have been often connected with large mortality increase in winter while their exact connection to winter weather remains largerly unclear [3].

In summary, answering this question is very difficult, since the greater understanding of joint effects of temperature and other seasonal effects is needed for correct interpretation of winter mortality patterns and its future projections [3,4]. Nevertheless, already recent studies suggest that aging population is going to be one of the main challenges of alleviating the impacts of extremely high temperatures on human health in developed countries [5].

Acknowledgments:

Thanks to Eva Plavcová and Hana Hanzlíková for reviewing this answer.

References:

[1] Gasparrini A, Guo Y, Sera F, et al (2017) Projections of temperature-related excess mortality under climate change scenarios. Lancet Planet Heal. doi: 10.1016/S2542-5196(17)30156-0

[2] While the highest-emission scenario assumes significant increase in green house gasses concentrations leading to increase in global surface temperature until the end of this century up to 6 °C compared to the historical baseline (1850–1900 average), more optimistic scenarios involve different levels of mitigation strategies to limit greenhouse emissions that would lead to less intense warming. Please see the summary of the Fifth Assesment Report of the the Intergovernmental Panel on Climate Change from 2013 for more information about the emission scenarios: http://www.climatechange2013.org/images/report/WG1AR5_SPM_FINAL.pdf

[3] Kinney PL, Schwartz J, Pascal M, et al (2015) Winter season mortality: will climate warming bring benefits? Environ Res Lett 10:64016. doi: 10.1088/1748-9326/10/6/064016

[4] Ebi KL (2015) Greater understanding is needed of whether warmer and shorter winters associated with climate change could reduce winter mortality. Environ Res Lett 10:111002. doi: 10.1088/1748-9326/10/11/111002

[5] Urban A, Hanzlíková H, Kyselý J, Plavcová E (2017) Impacts of the 2015 Heat Waves on Mortality in the Czech Republic—A Comparison with Previous Heat Waves. Int J Environ Res Public Health 14:1562. doi: 10.3390/ijerph14121562