While El Nino warms the planet when it happens, La Nina cools it. This year, the Pacific is in the grip of a powerful La Nina. It has contributed to torrential rains in Australia and to some of the coldest temperatures in memory in snow-bound parts of China. Increased sea temperatures on the western side of the Pacific means the atmosphere has more energy and frequency of heavy rain and thunderstorms is increased.
The World Meteorological Organisation's secretary-general, Michel Jarraud, told the BBC that the effect was likely to continue into the summer, depressing temperatures globally by a fraction of a degree. This would mean that temperatures have not risen globally since 1998 when El Nino warmed the world.
A minority of scientists question whether this means global warming has peaked and the earth has proved more resilient to greenhouse gases than predicted. But according to Jarraud, this was not the case and noted that 1998 temperatures would still be well above average for the century.
"When you look at climate change, you should not look at any particular year," he said. "You should look at trends over a pretty long period and the trend of temperature globally is still very much indicative of warming," added Jarraud.
"La Nina is part of what we call 'variability'. There has always been and there will always be cooler and warmer years, but what is important for climate change is that the trend is up," said Jarraud.