Countries could save countless lives and greatly reduce health costs if forewarned about climate-sensitive infectious disease outbreaks months in advance: and that is becoming a possibility, according to the Atlas of Health and Climate, a report mapping the links between climate and diseases like cholera, malaria, dengue fever and diarrhoea.
These diseases take the heaviest toll, according to the Atlas, a collaborative effort between the UN's World Health Organization (WHO) and World Meteorological Organization (WMO), and real-time maps showing possible spread could help prevention and treatment efforts. Diarrhoea kills over two million people every year, for example, and malaria kills nearly a million; both are influenced by climate variability.
But the Atlas authors say they still have a long way to go to make such warnings global and reliable.
“We have good real-time weather data, but that is not the case with health data,” said Geoff Love, WMO’s director of weather and disaster risk reduction. Disease outbreak data in most developing countries is typically collected by hand and often updated weekly. “There are also issues of respecting the privacy of individuals,” Love said.
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Yet with improvements in computer access, internet connectivity and digital media, health data collectors in deep rural interiors could contribute to regional and global datasets.
The agencies are currently focusing on the health impact of short-term changes in the climate, but the Atlas opens the door to long-term forecasts linked to climate change.
Modest global warming, starting in the 1970s, was causing over 150,000 excess deaths every year by 2000, according to a WHO study looking at the impact of climate-sensitive illnesses like diarrhoeal disease.
Countries, mostly in the developing world, could spend from US$6 million to $18 billion a year by 2030 managing the additional health costs resulting from climate change, a study based on the WHO assessment noted.
The Intergovernmental Panel on Climate Change, an international scientific body, said rising temperatures and the increasing frequency of extreme events could exacerbate malaria, cholera, Rift Valley fever and dengue fever in developing countries.
Diarmid Campbell-Lendrum, who leads the climate change and health team at WHO and is an author of the Atlas said, “One of the functions that we illustrate through the Atlas is that we can correlate climate and health information in places where we have both, and use the climate data to make health predictions, either for places where we have climate but not health information, or for the future."
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Much of the information in the Atlas is not new, says Campbell-Lendrum, but “what we are doing is to connect it together, and make it as accessible and clear as possible to decision-makers, from heads of health and meteorological agencies to field staff in disease-control programmes.
“This also includes the general public, who we hope will become increasingly 'climate-aware' in regards to their health. This is going to become more important as issues such as heat waves become more frequent through climate change, and vulnerability to health impacts increases through ageing, chronic disease rates, etc.”
For example, according to the Atlas, heat extremes currently expected to occur only once every 20 years may, by the middle of this century, occur on average every 2 to 5 years. At the same time, the number of older people living in cities - one of the groups most vulnerable to heat stress - will nearly quadruple globally, from 380 million in 2010 to 1.4 billion in 2050. The Atlas also shows seasonal linkages between diseases like meningitis and an increase in dust concentration and reduction in humidity levels in sub-Saharan Africa.
These and other findings make the case for more computer-generated climate models for tropical and waterborne disease outbreaks, says Campbell-Lendrum. There are very few, if any regional or country-level climate-change projections of possible diseases in developing countries.
“We already have many research studies in this area, but very few are converted into early warning systems or risk maps that are actually used for health decision-making,” he added.
WMO's Love said, "The Atlas is more of an advocacy document at this stage."