Sunday, January 10, 2010

The resurgence of El Niño means that 2010 could yet be the hottest year on record

Robin McKie in the Guardian (UK): …Britain may be shivering, the Met Office may have issued emergency weather warnings for the entire country and hundreds of trains and flights may have been cancelled, but our future is destined to be a hot and sticky one. And we are likely to feel the consequences sooner rather than later.

It is a point stressed by Doug Smith, a climate expert at the Met Office. "The hottest year on record was 1998 and some people have argued that if global warming is really taking place, we should have had an even warmer year since then. We haven't, I admit. And yes, the weather is absolutely terrible at present. However, I am sure things will change – and we won't have to wait long either."

Smith and other meteorologists say that for the past few years, temperatures have been prevented from soaring even higher than they did in 1998 thanks to one key factor: the El Niño warming of the Pacific. This phenomenon occurs at irregular intervals of between two and seven years and can last for months, pumping vast amounts of heat into the atmosphere. A strong El Niño occurred in 1998 and played a key role in heating the world to a record-breaking level. (El Niño is Spanish for "the boy", a reference to the birth of Christ, which relates to the fact that this warming period typically begins around Christmas.)

In recent years, however, the Pacific has cooled thanks to a corresponding ocean phenomenon, known as La Niña (Spanish for "the girl"). It depresses sea surface temperatures and has played a key role in limiting global warming since the turn of the century. As a result, global temperatures have been prevented from rising above their 1998 record level. That cooling has now stopped, however, and a new El Niño warming period has just started in the Pacific.

"If that keeps up for the next few months, it will result in a great deal of heat being pumped into the atmosphere," added Smith. "The signs are that it will. If so, our computer models indicate that this year is more likely than not to be the hottest on record. Even if it isn't, I am quite sure a record breaker will still occur in the next few years."….

During warm ENSO episodes the normal patterns of tropical precipitation and atmospheric circulation become disrupted. Image from NOAA

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