Perfect storm

Climate scientists think the El Niño effect is behind sudden Atlantic sea temperature rises. But could it be a sign of something much worse?

- Jonathan Watts and Julian Amani

Very unusual", "worrying", "terrifying", and "bonkers" - the reactions of veteran scientists to the sharp increase in north Atlantic surface temperatures over the past three months raise the question of whether the world's climate has entered a more erratic and dangerous phase with the onset of an El Niño on top of human-made global heating.

Since April, the warming appears to be on a new trajectory compared with the past. Meanwhile global sea ice has crashed down by more than 1m sq km below the previous low.

"If a few decades ago, some people might have thought climate change was a relatively slow-moving phenomenon, we are now witnessing our climate changing at a terrifying rate," said Prof Peter Stott, who leads the UK Met Office's climate monitoring and attribution team. "As the El Niño builds through the rest of this year, adding an extra oomph to the damaging effects of human-induced global heating, many millions of people across the planet and many diverse ecosystems are going to face extraordinary challenges and unfortunately suffer great damage."

The immediate impact is on marine life, unused to waters that have warmed by several degrees in some areas. More worrying still is the extra energy in the ocean, the world's biggest heat absorber, may bring fiercer-than-usual storms, more rain and longer, hotter heatwaves.

When the extremes in the north Atlantic started to be registered in April, the hope was this would be a temporary blip. In May, however, the average temperature in the region was the highest since records began in 1850. On 12 June, the climatologist Brian McNoldy calculated that, based on past data, there was a one in 256,000 chance of this happening,