ALL AT SEA

Climate change may have taken a back seat this year as countries grapple with Covid-19, but it hasn’t slowed down. Even long periods of lockdown barely made a dent in emissions, and the chain of wildfires, storms and floods is beginning to look like a global relay race in which one extreme weather event hands the baton on to the next.

Since the middle of last century, the world’s oceans have soaked up 93% of the extra heat energy we are generating.

But there is another less perceptible climate transformation under way, happening mostly out of sight below the waves of the ocean. Since the middle of last century, the world’s oceans have soaked up 93% of the extra heat energy we are generating by releasing greenhouse gases into the atmosphere – and they are now at their warmest in recorded history.

“Last year was by far the hottest in the ocean,” says Kevin Trenberth, a New Zealander who spent much of his career studying climate change at the National Center for Atmospheric Research in Boulder, Colorado, but returned home just before New Zealand’s lockdown.

“The past decade was also the warmest. If you look at the ocean heat