The return of El Nino

The spectre of flooding and drought in different parts of the world appears to be looming large as an increasing number of climate scientists predict the return of El Nino.

In its strictest sense, El Nino is the warming of the seas in the Pacific. Its counterpart is La Nina, a cooling of the same region.

They arise as a result of the Southern Oscillation, a see-sawing of pressure and wind between high pressure over the eastern South Pacific and low pressure centred near Indonesia.

Although the direct result of El Nino-La Nina is a change in ocean temperatures which have a dramatic effect on fish and bird life, the knock-on effect on weather patterns has a great impact on human activities around the globe. (Click on El Nino to find out more.)

The latest organization to predict its return is Australia’s Bureau of Meteorology. On Tuesday the Bureau said that there was a 70 percent chance of an El Nino, with its emergence predicted to be as early as July.

Meanwhile, Dr Wenju Cai, a climate expert at Australia’s Commonwealth Scientific and Industrial Research Organisation claims that a 6 deg C rise in Pacific Ocean temperatures in recent months, well in excess of previous El Nino years, and the rapid eastward movement of water in the Pacific, point towards a significant event.

“A strong El Nino appears early and we have seen this event over the last couple of months, which is unusual; the wind that has caused the warming is quite large and there is what we call the pre-conditioned effects, where you must have a lot of heat already in the system to have a big El Nino event.”

His conclusions are based on data released by the US National Oceanic and Atmospheric Administration.

The last major El Nino was in 1997-8. It was blamed for the flooding along the Yangtze River in China, which killed more than 1,500 people.

Globally, the economic cost of this event was calculated at $35 to $45 billion, largely as a result of its impact on the agriculture and fishing industries.