Climate change and the dangers in water

Julia Spierings

It goes without saying that in the future catastrophic weather events will affect people’s health globally more and more. Within the next ten years, surface temperatures will rise 1.4 to 5.8°C. An increase of this kind is the highest man has experienced in the last 10 000 years.  Approximately 600 000 deaths already occurred worldwide as a result of climate change related natural disasters, of which 95% in developing countries. On the long term, food and water scarcity and vector-borne diseases will endanger health. Areas with weak health infrastructure will be the least able to cope with the effects of climate change.

Natural disasters

Between 1992 and 2002, the weather event with the greatest impact was flooding, causing 100 000 deaths and affected over 1.2 billion people. Increased rainfall, rising sea levels and storms, which are strongly related to climate change will aggravate flooding in the future. The majority of the world population lives near water bodies, which makes them vulnerable for flooding. In low-income countries it will cause a loss of land and home, leading to social problems and breakdown of economies. Besides the direct damage of flooding, long-term effects might have more impact on our health. These effects of climate change on water mainly concern limiting resources and water-borne diseases.

Limiting resources

In some parts of the world, too much rainfall can devastate cultivation, fishery and cattle breeding. Higher sea levels will cause replacement of species, affect fishery, and elevation of the water temperature will cause plants to rampant. This endangers the sea life and the quality of water.  In other parts of the world, drought will challenge resources. Total harvests will decrease parallel to the rising temperature and increasing drought, thereby leading to malnutrition and a higher risk of infectious diseases. Water scarcity also leads to the contamination of water, which compromises hygiene and increases the risk of diseases. Furthermore, the growing population stresses the demand for resources. When scarcity develops, migration of people from the inlands to the coast or larger cities will enhance. Here, the increasing growth rates will also wear out supplies of ecosystem goods on the long term. Besides, these porous edges also provide refuge for the vectors of zoonotic disease transmission, and the risk of outbreaks of disease is therefore high. Could we be more trapped, considering that these areas are often located within 60 km of the sea where water will form another danger in floods or tsunamis?

Vector borne-diseases 

Climate change will increase the occurrence and distribution of vector borne-diseases. In these diseases pathogens are transmitted by an intermediary host, which often lives in water. Water scarcity encourages people to transport water on long distances and to store supplies in their homes. This increases the risk of contamination in the areas where there is no population immunity. Behavioural responses to the changing climate, such as variations in agricultural practices and demographic movements, will also influence transmission of diseases. Higher temperatures make vectors such as mosquitoes and snails bloom. Their geographic range will be altered and duration prolonged, seasonal variation will thereby decrease. These changes will concern the most fatal diseases, such as Vibrio cholerae. Studies show that every continent will be affected by these changes. In Australia for example, Liehne et al. described that alterations in water will trigger outbreaks of malaria, vector-born Murray Valley encephalitis and dengue, diseases that have not affected these regions in decades. Similarly, ticks, which are the vectors for Lyme disease, increasingly colonize cities in Canada due to the warmer climate. Experts say that more diseases such as malaria might be re-established in northern Europe and the US. 

 

 

 

Our contribution

In the future the impacts of climate on human health will increase. The vulnerable populations will be affected the most, while developed countries are the main contributors to the greenhouse effect. Where the slight emission reduction has no substantial effect and international agreements are insufficient, medical professionals can contribute. Some health risks can be avoided using existing prevention programmes, which should be promoted and supported. More studies concerning climate-health in developing countries are needed, as most available information comes from the developed world. And finally, we must prepare for the tropical diseases that are not that far away from us anymore. And perhaps, we could inform the pharmaceutical industry that the neglected market on medicines and vaccines for these diseases will interestingly grow in the more wealthy places in the near future. Potential changes in distribution of vector-borne diseases: malaria, lymphatic filariasis, onchocerciasis, schistosomiasis, African trypanosomiasis, leishmaniasis, dracunculiasis, rabies, dengue, yellow fever and arboviral diseases.

 

About the author

Julia Spierings is a sixth year medical student from Maastricht.

 

Further reading

• WHO report, Protecting health from climate change, Global research priorities 2009.
• GRIDA-Arendal, a collaborating centre of the United Nations Environment Programme.
• McMichael AJ, et al. Climate change and human health: present and future risks. Lancet. 2006

References

1. http://www.ciesin.columbia.edu/TG/HH/vb1.gif
2. Epstein, PR. Climate and health. Science, (1999).