How can modelling be applied to human health?
The challenge is to understand how the key factors affecting health will be altered by climate change
One approach is to sift through historical data to look for correlations between a past change in climate and human health. So a change in rainfall might have been linked to an increase in the spread of cholera, or a rise in sun exposure to additional skin cancers.
A related approach is to look for climate variables that show correlations with the incidence of disease – typically infectious disease. A good example is the spread of dengue fever, caused by the world’s most common mosquito-borne virus.
Numbers of dengue-carrying mosquitoes are strongly dependent on temperature, moisture levels and sunshine. Indeed, a computer simulation used to predict mosquito numbers on the basis of these variables provided a good match for the yearly incidence of dengue disease in a range of countries, from Honduras to Thailand.
The most significant short-term ‘natural’ climate variation is the El Niño. Rainfall and temperature changes seen in El Niño events have been linked to epidemics of several tropical diseases. The 1997–98 El Niño event raised winter temperatures to 5°C above average in Lima, Peru, more than doubling the number of daily hospital admissions for diarrhoea.
Knowing when El Niño is due can enable countries to prepare for its impact. People can protect themselves from its direct effects, such as storms. In addition, countries such as Botswana now know that as simple a measure as sea surface temperature, through its effects on rainfall, will have a major impact on the spread of malaria, giving them several months’ advance warning of a possible epidemic.Lead image:
Sanofi Pasteur/Patrick de Noirmont/Flickr CC BY NC ND
- Climate’s strong fingerprint in global cholera outbreaks
- World Health Organization: Dengue
- Distribution, seasonal variation and dengue transmission prediction in Sisaket, Thailand (2013) [PDF]
- Effect of El Niño and ambient temperature on hospital admissions for diarrhoeal diseases in Peruvian children (2000)
- Use of rainfall and sea surface temperature monitoring for malaria early warning in Botswana (2005)