A key measure of El Nino weather patterns eased in June, suggesting the potentially damaging condition may be developing slowly, although India's monsoon will remain weak, Australia's weather bureau said.
An El Nino, which means "little boy" in Spanish, is driven by an abnormal warming of the eastern Pacific Ocean, and creates havoc in weather patterns across the Asia-Pacific region.
The Southern Oscillation Index (SOI), a key factor in identifying an El Nino that is calculated from monthly and seasonal fluctuations in air pressure between Tahiti and Darwin, eased in June to negative 2 from a negative 5 in May, the bureau said on Tuesday.
A sustained negative SOI often indicates El Nino, a condition that can bring drought conditions to Australia's farmlands, weaken the Asian monsoon critical for Indian crops, stir up storms in the Gulf of Mexico and cause flooding in Latin America.
"Minus 10 is an often used threshold level and it just got to there a few times, but it hasn't been sustained at that level," Sam Cleland, author of the Bureau of Meterology's weekly Tropical Climate Note, said on Tuesday.
"I don't think we'd make the call just yet that we have an El Nino event in place," he said ahead of the bureau's El Nino update on Wednesday.
Its last report said an El Nino was very likely in 2009 and may be declared in coming weeks. The last El Nino was in 2006....MORE
Across the globe an emerging El Nino weather pattern threatens to cause droughts and floods and trigger a spike in planet-warming greenhouse gas emissions from burning forests.
El Nino is a warming of tropical Pacific waters that affects wind circulation patterns. Its effects on the global climate vary from one event to the next.
Trying to predict how El Nino will be affected by global warming is a major challenge, scientists say, although data shows El Ninos have become more frequent and more intense over the past three decades. The last event was in 2006.
"I don't think there are any studies that are saying El Nino will become less severe but there is disagreement among the climate models on whether they will become more severe or stay steady," said Matthew England of the Climate Change Research Center in Sydney.
Getting the forecasting right is crucial for farmers in planning their crops, and even for the oil industry in assessing storm risks in the Gulf of Mexico.
"Certainly we know from past climates that El Nino intensity has varied. As climate changes, we know that the intensity of El Nino can wax and wane over long time scales," he said.
Australia's Bureau of Meteorology said last week an El Nino was almost certain this year and the signs point to one already well underway. A formal declaration could be within days.
(For more details see the bureau's website at: www.bom.gov.au/climate/enso/)
One of the biggest threats from El Nino comes from the release of vast amounts of greenhouse gases through the burning of dried out forests.
Scientists say there is very strong correlation between El Nino and drought in Southeast Asia, which has large areas of carbon-rich peat forests....MORE