Special feature: It's existential - climate change and life & health

While not all the threats of climate change are fully understood, it fully emerged as a present real life risk. The most pronounced risks from climate change affecting human health stem from heatwaves, floods, droughts, fires and vector-borne diseases. Millions of lives can be saved and the burden on healthcare services reduced if we pay more heed to changing climates. Without action, mortality rates and healthcare costs could soar,1 and this would have significant consequences for the health, workersʼ compensation and life insurance lines of business.2

Changes in mortality will be driven by several changes occurring simultaneously. First, we expect that heatwaves will become more severe and extend to areas previously not impacted. This includes in the temperate zone, where a large proportion of the worldʼs population lives. The 2003 heat wave in France was a first taste of things to come. It caused 70 000 deaths – mainly among the elderly.3 With no mitigation, and with rapidly ageing populations in many countries, a future event will have an even bigger impact because the share of vulnerable older populations in the affected regions is rising fast.4

Increasing temperatures and high humidity due to climate change is another area of concern, in that this combination enables vector-borne diseases to conquer new ground. The West Nile and Zika epidemics were first warning signs.5 Climate change will extend the transmission season and geographical range for many infectious diseases.6 For example Lyme disease, avian influenza, meningitis, dengue fever and tropical bacterial and viral infections are projected to increase with climate warming, including potential shifts in their geographic range.7 Severe drought conditions can lead to increased wildfires, which in turn lead to air pollution. This is even in areas far away from any conflagration, as the California wildfires of 2018 showed.8

Knock-on effects
The secondary impact of climate change will amplify the above. In focus here are migration, urbanisation, food security & nutrition, and water scarcity. Already today, more than 2 billion people live in areas of water stress,9 areas where access to clean water for drinking, sanitation and personal hygiene – all pre-requisites for public health – is limited.10 The number of regions affected by water stress will increase as temperatures rise. Public health could be further compromised by the expected increase of, for example, extreme heat, droughts and floods affecting agriculture. This will diminish or destroy the nutritional supply chains that help people withstand health threats.11 Nor will fishery compensate because rising sea temperatures and ocean acidification will likely mean lower catches.12

Extreme weather events will not only impact agriculture. With continued sea level rise,13 storm surges may reach further inland. With increased value concentration in mega-cities exposed to storm surges, economic and insured losses are likely to increase further. So too will the risk of epidemics. Migration to urban centres is concentrating an ever larger share of the worldʼs population in a small areas. As has happened many times before, storms and floods that destroy infrastructure can trigger significant epidemics. And, once the flood water recedes, toxic mould may remain in buildings, posing yet another threat to public health.

In polar and other regions were permafrost has long been the environment norm, another possible consequence of warmer temperatures could be the release of older bacteria and viruses as ice thaws. Having not been exposed to these strains for thousands of years, the immunity of the worldʼs population to such threats will be low. The building of new harbours to accommodate increasing marine traffic with the opening up of the arctic sea route, will make it more likely viruses or bacteria will be able to travel to far distant locations, triggering an epidemic or pandemic. Such outbreaks could be especially serious if the bacteria prove resistant to antibiotics (see section in the 2017 SONAR report on antibiotic resistance).

Becoming climate resilient in public health
The world community has acknowledged the imperative with the “Paris agreement on climate change” which aims to keep global warming well below 2 degrees Celsius in the long-term. In addition, it outlined in the WHO COP 24 special report on Health & Climate change what to do to save lives, reduce epidemics and make public
health climate resilient.14

The immediate public health activities necessary to meet the challenge of climate change are to strengthen the prevention of climate-sensitive health risks and to build an adaptive skill set to absorb the changing, increasing risks presented by climate change described before. This also involves related sectors like food security and safety or sanitation. Additionally, however, there are other specific risks the health sector must address to achieve resilience in the face of climate change.

Health care facilities are the operational heart of service delivery, protecting health and treating patients, both during and after weather and climate-related events (such as heat stroke during heatwaves and injuries during cyclones) and in response to other environmental risks to health (such as asthma due to poor air quality). Health care facilities in poor and rich countries alike must be able to deliver in changing climate conditions, such as during extreme weather events. Cooling systems during heat days, flood security, emergency power and water supplies must become standard in health care facilities worldwide.


[1] COP24 Special Report: Health and Climate Change, World Health Organisation, 2018

[2] sigma 6/2018, op. cit.

[3] Death toll exceeded 70 000 in Europe during the summer of 2003, Comptes Rendus Biologies, Vol. 331, No, 2, February 2018

[4] The 2018 report of the Lancet Countdown on health and climate change: shaping the health of nations for centuries to come, The Lancet, 8 December 2018

[5] Impacts of 1.5C of Global Warming on Natural and Human Systems, IPCC, 2018

[6] Human health and adaptation: understanding climate impacts on health and opportunities for action. Synthesis paper by the secretariat, United Nations, March 2017

[7] Impacts of 1.5C of Global Warming on Natural and Human Systems, op. cit.

[8] ʼNo fresh airʼ: wildfire smoke sets apocalyptic haze over San Francisco, The Guardian, 13 November 2018

[9] SDG 6 Synthesis Report 2018 on Water and Sanitation, United Nations, 28 June 2018

[10] Human health and adaptation: understanding climate impacts on health and opportunities for action. Synthesis paper by the secretariat, op. cit.

[11] The State of Food Security and Nutrition in the World, Food and Agriculture Organisation of the United Nations, 2018

[12] Heatwaves take their toll on the high seas, Nature: international journal of science, 4 March 2019

[13] Impacts of 1.5C of Global Warming on Natural and Human Systems, op. cit.

[14] COP24 Special Report: Health and Climate Change, op. cit.