El Nino Triples Cases of Diarrheal Disease
A study which has revealed the huge impact of El Nino on human diseases may provide clues as to what to expect in future with global warming.
The Lancet reports that a study of 57,000 children in Lima found diarrheal disease vastly increased during the 1997-98 El Nino season. El Nino is a warming of the Pacific Ocean every two to seven years which leads to extreme climate changes. It leads to warmer temperatures in Lima, and has previously been linked to outbreaks of dengue fever, malaria and cholera.
The study, by researchers from the US John Hopkins School of Public Health and the Instituto Nacional de Salud shows a direct link between El Nino and disease. They estimated that diarrhoea-related diseases, such as those caused by E. coli and salmonella, increased more than eight per cent with every one degree C rise in temperature.
The researchers said that future El Ninos will be able to be predicted several months in advance. This will allow preventative actions, such as oral rehydration and water chlorination, to be taken to reduce fatalities. The findings suggested a possible link between diarrhoeal disease and global warming, but more studies would be needed to confirm this.
Meanwhile Norwegian researchers published in Science have found a possible benefit from global warming in helping to boost songbird populations.
Using population models, researchers from the Norwegian University of Science and Technology have found that populations of the dipper Cinclus cinclus would jump by almost 50 per cent with global warming.
The dipper is a small bird which lives and feeds next to running water, and its population size is strongly affected by the amount of ice, and therefore the amount of feed available in winter. This in turn depends on temperature and rainfall. Studying fluctuations in the bird's population over 20 years, the researchers found that when winters were colder and there was more ice around, populations were smaller because birds couldn't find food.
Using models of temperature change developed by the Intergovernmental Panel on Climate Change, the researchers calculated that in one global warming scenario, the carrying capacity of the environment where the birds lived would increase by 58 per cent, and the local population would jump from 117 to 184.
Other climate change studies have shown that some birds will lay eggs earlier in the year because of warmer springs, and spawning rates of some amphibians will increase. The researchers comment that relatively small changes in temperature could in future have a major impact on bird populations around the world.