Ocean warming worse than thought

Oceans have warmed as much in the last 20 years as they did in the previous 130 years, according to a new study.

The paper, published in the journal Nature Climate Change, drew on data from as far back as 1865 in its findings about oceanic heat content.

Scientists compared data from two main scientific expeditions: the HMS Challenger in the 1870s and the Argo floats in 2004-10. They estimate that the ocean has absorbed 3.3 x 10²³ joules of energy more than it otherwise would have if capitalist industrialisation had not occurred.

To put that figure in perspective, the excess heat energy in the ocean is equal to perhaps 60 million years’ worth of Melbourne’s current household electricity use.

Thirty-five percent of the heat created by industrial activity is stored at depths below 700m. Just 20 years ago, the deep ocean contained only 20 percent of the warmth created by human release of greenhouse gases.

This rapid increase in ocean warming is worrying scientists, who speculate that it could affect ecosystems that humans have little knowledge about.

The chief author of the study, Peter Gleckler, told the Guardian, “When we discuss global warming, the most familiar way we do that is talk about temperature changes on the surface – but it’s clear that the oceans are doing the bulk of the work in terms of absorbing the heat in the system.

“And if we want to really understand how much heat is being trapped, we can’t just look at the upper ocean any more, we need to look deeper.

“The findings are concerning. It’s clear evidence that the oceans are taking the brunt of the greenhouse gases and are accumulating a lot of heat. As for the ecological implications, that’s hard to say. There is a lot of life in the deep oceans and there’s lots we don’t know about the impact upon that life.”