Fast forward 25 years, and Trenberth still sees changes in ocean temperature as key to understanding the ups and downs of global climate. That includes the current plateau in global temperature.
Trenberth says, in fact, the planet has continued to warm during this time — but the heat has been flowing into the oceans, which have a vast capacity to absorb it.
So will the oceans come to our rescue?
“That’s a good question, and the answer is maybe partly yes, but maybe partly no,” [Kevin Trenberth] says.
The oceans can at times soak up a lot of heat. Some goes into the deep oceans where it can stay for centuries. But heat absorbed closer to the surface can easily flow back into the air. That happened in 1998, which made it one of the hottest years on record.
Trenberth says since then, the ocean has mostly been back in one of its soaking-up modes.
“They probably can’t go on much for much longer than maybe 20 years, and what happens at the end of these hiatus periods, is suddenly there’s a big jump [in temperature] up to a whole new level and you never go back to that previous level again,” he says.