5 Mar 2015

El Nino arrives – finally…

In April last year, the World Meteorological Organization issued a press release saying that an El Nino event was possible in the following months.

However, despite many weather computer models generally pointing to such an event happening by summer 2014, the meteorological community waited and waited.

Summer came and yet there was still no sign of El Nino, with the ocean and atmosphere not exhibiting the synchronicity that allows El Nino to be declared.


Finally, it was announced today, by NOAA’s Climate Prediction Center, that El Nino has officially arrived – more than six months after originally expected and much weaker in strength.

What is El Nino and why is it important?

El Nino is a naturally occurring ocean-atmosphere phenomenon that is characterised by unusually warm surface water temperatures in the central and eastern Pacific.

It is important because it has a significant impact on the climate in many parts of the world.


El Nino’s influence on temperature

The most notable effect that El Nino has on the climate is a warming influence on global average temperatures – something that was observed during a strong El Nino in 1998.

However, it should be noted that no two El Nino events are ever the same and its effects will work with other drivers that influence the world’s climate system.

Nevertheless, historical data shows that the effects of El Nino can be felt far and wide – much like dropping a pebble in a pond and the ripples extending outwards.


El Nino’s influence on precipitation

Given that this current El Nino event is weak, NOAA says that widespread or significant global impacts are not anticipated.

However, certain impacts often associated with El Nino may appear in some locations during the Northern Hemisphere spring 2015.

The perils of seasonal forecasting

As time progressed last year, each subsequent El Nino update from NOAA not only reduced the percentage chance of an El Nino event occurring, but also weakened its projected strength.

There is no doubt that many of the world’s experts will be left scratching their heads as to why El Nino didn’t happen when and to the strength that many climate models were predicting.

This highlights the questionable reliability of seasonal forecasts and also offers a reminder that despite the significant progress made with improvements to both modelling and supercomputers, there are still some things that are not fully understood.

I’ll be keeping a close eye on El Nino and its possible influences on weather around the world in the coming months, posting updates in this blog and on Twitter – @liamdutton

Images: NOAA, Met Office

Tweets by @liamdutton