Ancient fossilised clams that lived off the coast of Antarctica have linked current climate change to similar change from around 50 million years ago.

“Clams, like trees, respond to changes in climate by growing faster or slower. Therefore, the width of the annual growth rings correlates with environmental variables like temperature or precipitation,” Syracuse University researcher Linda Ivany said.

The evidence from the clams suggests that as the planet warms up there will still be an oscillation between normal and El Niño years.