Signs have been detected that a periodic warming of the tropical Pacific known as El Nino is imminent, presaging changes to global weather patterns in the months ahead, the World Meteorological Organization said.
Water temperatures below the surface of the Pacific’s equatorial waters have warmed to levels similar to the onset of El Nino, and about two-thirds of climate models indicate thresholds for the phenomenon may be reached from June to August, the United Nations’ WMO said today in an e-mailed statement.
El Ninos occur irregularly every two to seven years and are associated with warmer than average years. They tend to lead to abnormally dry conditions over parts of Australia, the Philippines and Brazil, and to more intense storms in the Gulf of Mexico. Their counterpart, La Ninas, are associated with cooler years.
“El Nino and La Nina are major drivers of the natural variability of our climate,” WMO Secretary-General Michel Jarraud said in the statement. “If an El Nino event develops, and it is still too early to be certain, it will influence temperatures and precipitation and contribute to droughts or heavy rainfall in different regions of the world.”
The last El Nino was from 2009 to 2010. The strongest El Nino measured to date ran from 1997 to 1998 and contributed to 1998 being the third-warmest year on record.
“El Nino has an important warming effect on global average temperatures, as we saw during the strong El Nino in 1998,” Jarraud said. “The combination of natural warming from any El Nino event and human-induced warming from greenhouse gases has the potential to cause a dramatic rise in global mean temperature.”
El Nino events tend to lead to dry conditions in northern Australia, the Philippines and Indonesia, as well as drier periods in southeastern Africa and northern Brazil during the southern hemisphere’s summer, according to the WMO, a UN agency.
During the northern summer, Indian monsoon rains tend to diminish, harming crops, while the west coast of tropical South America gets wetter. Western Canada and Alaska usually get warmer winters, and the Gulf of Mexico gets more vigorous storms, it said.