Floods in Peru from a severe El Ni帽o event 17 years ago have stunted the growth of children born around that time by several centimetres.
鈥淭he children鈥檚 height was permanently marked just like ,鈥� says of Johns Hopkins University in Baltimore, Maryland.
The floods destroyed crops and roads, so the shortfall in growth probably occurred as a result of malnutrition caused by food shortages, diarrhoea due to dirty drinking water, and a lack of access to healthcare, says Checkley.
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The is a cyclical weather event that happens every two to seven years, when warming at the surface of the Pacific Ocean brings extra rainfall to the Americas for an extended period. It also causes drought in Australia and affects many other countries.
Backwards step
The El Ni帽o that spanned 1997 and 1998 was especially severe, causing 16 times more rain than usual in a coastal region of Peru called Tumbes, in the north-west of the country. The resulting floods cut off access to roads, isolating some rural villages for months.
In 2008 and 2009, Checkley鈥檚 team visited 59 villages in the area and measured the heights and weights of more than 2000 children aged between 7 and 17 鈥� the oldest would have been 6 during the event and the youngest would not have been born. The team used historical satellite data and weather records to work out the probability that the family home was hit by the floods.
Before the El Ni帽o, children in that region had been gradually gaining height as a growing economy made more food available and public health improved. Each year 10-year-old children, for instance, were on average 0.6 centimetres taller than children of the same age the year before.
But after 1997 that trend went into reverse. Children born during the El Ni帽o period were on average 0.3 cm shorter than they would have been if the gains in height had continued.
More dramatically, those from the villages most likely to have been affected by floods were 4 cm shorter. 鈥淭he event wreaked havoc in the area,鈥� says Checkley. The flooding caused yields of crops such as bananas and rice to plummet and probably caused the spread of diseases such as diarrhoea and malaria.
Indelible stamp
The effect on height persisted for children born at least three years after the El Ni帽o, the point up to which the heights were surveyed. Checkley鈥檚 team also found that children born after the El Ni帽o had reduced muscle mass, which he says would affect their capacity for physical work later on, important in an agricultural and fishing community such as theirs. Other studies have found that stunting in childhood can have lasting effects on people鈥檚 physical and mental health, including raising the risk of chronic conditions such as heart disease.
He adds that the findings emphasise the need to warn developing countries when a severe El Ni帽o is likely, so they can improve their flood defences and target aid to affected villages.
of the UK Met Office says El Ni帽o forecasting is generally quite accurate. It is possible to predict an event several months in advance and give an idea of its 鈥� while localised predictions cannot be made, countries that are normally affected by the event can at least be warned they will be hit worse than usual. 鈥淓l Ni帽o is the cornerstone of long-range forecasting,鈥� he says.
However, of the University of Giessen in Germany points out that earlier this year he and several other forecasters predicted a severe El Ni帽o for 2014, which has yet to materialise. 鈥淚n three out of four cases our forecasts are correct,鈥� he says. 鈥淏ut right now we are still unable to predict the strength of the next El Ni帽o.鈥�
Journal reference: Climate Change Responses, in press
