Rising sea surface temperatures across the central and eastern Pacific Ocean herald El Niño, which could disrupt the rains in major cereal producing regions, the World Meteorological Organization (WMO) has warned.
"Typically, an El Niño has the potential to disrupt the rainy seasons and cause lower rainfall in India, Australia, Southeast Asia - Philippines and Indonesia - southern Africa and Central America," said Robert Stefanski, a WMO scientific officer who works on agriculture-related weather and climate issues. "In past El Niño events, droughts have occurred and lowered food production in many of these regions."
In contrast, La Niña is the cooling of sea surface temperatures; both El Niño and La Niña are part of the normal climate cycle in the Pacific Ocean and occur once every four to seven years. According to WMO, "Recent changes are consistent with the early stages of a developing El Niño event in the second half of 2009."
A coming El Niño should be taken as an "early warning to potential problems related to food security, and this information is useful for agricultural decision-makers to plan for the upcoming season," said Stefanski.
The Australian Bureau of Meteorology's National Climate Centre warned in early June that "the odds of an El Niño are now thought to be above 50 percent, which is more than double the normal risk of an El Niño in any year."
|A coming El Niño should be taken as an early warning to potential problems related to food security, and this information is useful for agricultural decision-makers to plan for the upcoming season|
The main impact of El Niño events usually occur in the second half of the year, when eastern, northern, and parts of southern Australia would face an increased risk of below-average rainfall and above-average daytime temperatures, the Bureau said. Australia is the world's fourth largest exporter of wheat.
"Any impact [of El Niño] on food production will be noticed after December 2009," said Liliana Balbi, a senior economist at the UN Food and Agriculture Organization (FAO) Global Information and Early Warning System.
In Australia, "planting of the 2009 main winter cereal crops has been completed successfully, with reports until late June indicating favourable prospects," she said.
The monsoons are late in India, the world's third largest wheat producer. "Historically, there has been a link between El Niño and the Indian monsoons," said Stefanski. Studies have shown that sea surface temperatures also affect this critical rainy season.
The tardy monsoon in parts of Southeast Asia has raised alarms of "potential food emergency problems, for example, in India," said Balbi. "In Pakistan, rains for the secondary rice season are also delayed." However, Sri Lanka has had a good harvest.
In Ethiopia, Sudan and Eritrea the main seasonal rains are out-of-step, and insufficient in parts of Kenya. Eastern Africa is already facing one of the worst food crises in recent times. "We are closely monitoring the relation of these developments with El Niño." In southern Africa, "the 2009 main maize season harvest has just been concluded, so we do not expect any immediate effects," said Balbi.
Not the last word
Stefanski noted that "There are many additional factors besides El Niño that determine the climate for the next three to six months in each region of the world."
Timely rain could limit the worst effects of El Niño to relatively small areas, as happened in 1997, when the event was intense. "We were anticipating one of the worst droughts for southern Africa, but it did not happen," he said.
The focus of the upcoming World Climate Conference Three (WCC-3) in Geneva, being organized by WMO from 31 August to 4 September 2009, is the use of climate information as an early warning tool - "climate prediction for decision-making".