A gigantic blob has surfaced in the Pacific, a monster of unusually cool water stretching out from South America across the equator. This is La Niña and it could send the world’s weather haywire over the next few months. Its impact could even be felt in Britain. Seven years ago one of the most powerful La Niñas on record led to catastrophic floods in Queensland, Colombia, southern Africa, and Pakistan, as well as drought in east Africa and the Amazon. There were record snowfalls followed by spring floods in the US.
In the UK there was a corresponding savage freeze. November 2010 began mild, then turned unbelievably cold towards the end of the month, with Northern Ireland and Wales breaking their lowest temperature records for November.
The following month was worse, the coldest December for more than 100 years, and one of the coldest of any month on record – Altnaharra in the Scottish Highlands registered a low of -21.3C.
The UK turned into a magical winter wonderland of ice crystals – trees, fences and blades of grass looked as if they had been sprayed with icing sugar, glittering and sparkling in the winter sunshine. This was a thick frost called rime, a classic hallmark of incredibly cold weather.
Basing winter predictions in Europe on the strength of La Niña is a dangerous game to play, of course, as there are often other competing global weather phenomena which can throw a spanner in the works. But there is undoubtedly a link between La Niña and colder than average northern hemisphere winters.
This time around this new phase of La Niña is expected to be much weaker than was the case in 2010-11.
