July 29, 2012

A variant of El Niño?

Just when I discovered "derecho," the word for the super wind storm and thought I was beginning to understand the difference between El Nino and La Nina, ScienceDaily adds another new word to my environmental vocabulary.

El Nino emerges once every two to seven years in the equatorial Pacific, causing weather changes globally. But in the past ten years, it has changed its face. It is increasingly taking the form of Modoki, 'similar but different' as it was baptised by the Japanese team who first discovered this less tumultuous cousin that provokes droughts in India and Australia.

This El Niño variant is centred in the central pacific, unlike its eastern relative. In Modoki episodes, scientists have observed low levels of chlorophyll in the center of the Pacific basin. Why is this important? Less aquatic nutrients for sealife for one thing.

Another is a a factor in climate change. Under 'normal' conditions above the Pacific, the trade winds blow strongly from east to west. When a classic El Niño episode occurs, the trade winds experience a huge drop in force.

But when Modoki occurs, the trade winds hardly drop in force. This could affect our hurricane season. Another result scientists found was colder, richer waters to the east, along the South-American coastline. This cold water rising from the deep is rich in the nutrients that support new life in the region's seas. That's good news for the fishing industry.