France 2003: A Case Study

Following the recent IPCC report[1] showing that radical change is needed to avoid significant temperature change (with catastrophic environmental effects) we thought it might be valuable to look at a specific incident where climate change directly contributed to human mortality. As such, here is a case study on the heatwave that hit Europe (and France in particular) in 2003.

In July-August 2003 record high temperatures hit accross Europe to create the hottest summer since 1500[2]. Temperature highs were measured in the 40s for multiple consecutive days leading to a large increase in morbidity and mortality, particularly in the elderly[3]. This was particularly noticed in France where all-cause mortality for the month of August was significantly higher than in any of the preceding years across all major cities[4].

Now this increase was studied as all-cause mortality rather than death directly from temperature conditions (in this case, heatstroke). This is due to the increase strain from the temperature provoking a deterioration in pre-existing conditions (hence the elderly, infants, people with co-morbidities, or anyone with poor physiological reserve being increasingly at risk). However, heat itself can cause morbidity and mortality as the body loses its ability to dissipate heat. This is due to surface/environment temperature matching core body temperature, destroying the gradient that allows for natural dissipation.

Heat illness exists as a spectrum starting mild (heat cramps) before moving on to potentially fatal (heat stroke). Heat cramps occur while the body still retains heat dissipation mechanisms (such as sweating) and produces cramps, tachycardia, and intense thirst (but no impact on neurological function). Heat exhaustion occurs at a higher temperature but when dissipation mechanisms are still intact. It produces a variety of symptoms including nausea, weakness, oliguria, headache, thirst, but can include some milder neurological symptoms (such as confusion, irritability, and poor co-ordination).

Heat stroke is the most extreme form of heat illness and is potentially fatal. It is a combination of hyperthermia (core temperature above 40.6), a loss of heat dissipation mechanisms, and deterioration in central nervous system function. Initially there is hyperventilation, loss of sweating, hypotension, and shock. As temperature increases it can cause widespread damage to muscles and organs. Additionally, it can trigger cytokine cascades causing inflammatory damage while also causing coagulopathies. If not treated (with hydration, supportive measures, and cooling) the patient will die.

The extreme summer and accompanying increase mortality has been linked to human factors[5],[6] and is an example of the direct effects that climate change can have on the global population. Global temperature increases will lead to more extreme temperature events (both heatwaves and cold snaps) leading to further all-cause mortality[7]. This is alongside the increasing risk of morbidity and mortality from food shortages[8], increase in other extreme weather events[9], and direct loss of land to rising sea levels[10].

The IPCC report spells things out clearly. We are already seeing the effects of a 1 degree celsius increase in temperature. Things will get worse if measures to limit further increases aren’t put in place. These measures need to be radical and need to cross geopolitical spectrums. Climate change is a global health emergency and needs to be treated as such.

Author Details: Dr. Eliot Hurn, Foundation Year 2 County Durham and Darlington Foundation Trust.

[1] Intergovernmental Panel on Climate Change (2018). Summary for Policymakers of IPCC Special Report on Global Warming of 1.5ºC approved by governments. [online] Intergovernmental Panel on Climate Change. Available at: [Accessed 15 Oct. 2018].

[2] Luterbacher, J., Dietrich, D., Xoplaki, E., Grosjean, M. and Wanner, H. (2004). European Seasonal and Annual Temperature Variability, Trends, and Extremes Since 1500. Science, [online] 303(5663), pp.1499-1503. Available at:

[3] Vandentorren, S., Bretin, P., Zeghnoun, A., Mandereau-Bruno, L., Croisier, A., Cochet, C., Ribéron, J., Siberan, I., Declercq, B. and Ledrans, M. (2006). August 2003 Heat Wave in France: Risk Factors for Death of Elderly People Living at Home. European Journal of Public Health, [online] 16(6), pp.583-591. Available at:

[4] Vandentorren, S., Suzan, F., Medina, S., Pascal, M., Maulpoix, A., Cohen, J. and Ledrans, M. (2004). Mortality in 13 French Cities During the August 2003 Heat Wave. American Journal of Public Health, [online] 94(9), pp.1518-1520. Available at:

[5] Stott, P., Stone, D. and Allen, M. (2004). Human contribution to the European heatwave of 2003. Nature, [online] 432(7017), pp.610-614. Available at:

[6] Mitchell, D., Heaviside, C., Vardoulakis, S., Huntingford, C., Masato, G., P Guillod, B., Frumhoff, P., Bowery, A., Wallom, D. and Allen, M. (2016). Attributing human mortality during extreme heat waves to anthropogenic climate change. Environmental Research Letters, [online] 11(7), p.074006. Available at:

[7] Christidis, N., Jones, G. and Stott, P. (2014). Dramatically increasing chance of extremely hot summers since the 2003 European heatwave. Nature Climate Change, [online] 5(1), pp.46-50. Available at:

[8] (2018). Climate Impacts on Food Security – WFP. [online] Available at: [Accessed 15 Oct. 2018].

[9] American Meteorological Society (2018). EXPLAINING EXTREME EVENTS OF 2016 FROM A CLIMATE PERSPECTIVE. Explaining Extreme Events from a Climate Perspective. [online] American Meteorological Society. Available at: [Accessed 15 Oct. 2018].

[10] (2018). Office of the High Commissioner of Human Rights – United Nations. [online] Available at: [Accessed 15 Oct. 2018].

NB: Clinical information regarding heat illness from Patient UK,

Author Details: Dr. Eliot Hurn, Foundation Year 2 County Durham and Darlington Foundation Trust.

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