According to the World Health Organization (WHO), nearly a quarter of worldwide deaths and disease burden are owing to environmental factors. As the environment changes as a result of climate change, what will happen to health?
According to the World Health Organization (WHO), nearly a quarter of worldwide deaths and disease burden are owing to environmental factors. As the environment changes as a result of climate change, what will happen to health?
As usual, the answer is 'it depends'; both on where you are and who you are. We are lucky that there are several major international reports that look at the risks and impacts of climate change and their effects on health. There are some interesting angles that might not immediately spring to mind.
What is obvious, though, is that the health impacts of climate change will vary widely between countries and between different population groups within countries. Although there are likely to be some beneficial impacts, they are vastly outweighed by the deleterious impacts.
Although this overall picture is reasonably clear, the details are not; they depend not only on the detailed effects of climate change, which are themselves uncertain, but also on factors such as social and political circumstances and responses to change. As an example, the prevalence and severity of vector-borne diseases - infectious diseases transmitted by living organisms such as insects - depend on complex transmission cycles involving vectors, other intermediate hosts and humans. The factors influencing these cycles include climate factors, as well as how pathogens adapt and change, the availability of hosts, changing ecosystems and land use, demographics, socioeconomic and sociocultural factors, and prioritisation of vector control.
The impacts on health are further affected by factors such as access to healthcare and human behavioural responses to perception of disease risk. On top of all this, some of the effects are highly non-linear - small temperature differences can have large effects under some circumstances.
Aspects of health that can be directly affected by climate change include:
- Temperature-related illness and death
- Injuries
- Mental health
- Cardiovascular, respiratory, skin and neurological diseases
- Vector-borne diseases
- Gastro-intestinal illnesses
- Undernutrition
- Skin cancer
- Cataracts.
In addition, there are likely to be substantial indirect effects. The health impacts from possible large-scale alterations to earth's natural systems may well outweigh the direct effects of climate change, especially in poorer countries. Both water and food security are likely to be affected, and there may be major population displacements and civil unrest. For example, it is thought that the 2007-2010 drought contributed to the Syrian uprising that began in 2011.
In richer countries, the risks to health infrastructure from climate change may be significant: in the UK, for example, many health facilities are vulnerable to flooding, and severe weather events may prevent health professionals getting to work. The operational risks to healthcare from severe weather events may be highly significant, making healthcare simply unavailable just when it is most needed.
In addition, there may be reduced funding available for healthcare in many countries owing to adverse economic impacts of climate change.
As well as varying widely by country, the impacts will also vary between population groups within individual countries. In general, those most affected include the elderly, the poor, and those with chronic conditions. This may mean, for example, that people in long-term care are more affected than the population at large.
The complexity of the interactions between climate change and other factors mean that projections of future mortality and morbidity rates will inevitably rely on many assumptions.
For instance, they may implicitly assume that factors such as the availability of healthcare, the prevalence of various diseases, and the nutritional status of the population remain constant, if these are not the specific effects that are being analysed. Actuaries using such projections will need to consider the assumptions that have been made in the context of the situation in which they are applying the projections.
This article is a summary of a paper presented at the recent IFoA Health and Care Hot Topics sessional meeting: bit.ly/2fJJ0jz
Louise Pryor is an actuary at Callund Consulting