Worries over sudden ocean warming spike

WASHINGTON

The world’s oceans have suddenly spiked much hotter and well above record levels in the last few weeks, with scientists trying to figure out what it means and whether it forecasts a surge in atmospheric warming.

Some researchers think the jump in sea surface temperatures stems from a brewing and possibly strong natural El Nino warming weather condition plus a rebound from three years of a cooling La Nina, all on top of steady global warming that is heating deeper water below. If that’s the case, they said, record-breaking ocean temperatures this month could be the first in many heat records to shatter.

From early March to this week, the global average ocean sea surface temperature jumped nearly two-tenths of a degree Celsius, according to the University of Maine’s Climate Reanalyzer, which climate scientists use and trust. That may sound small, but for the average of the world’s oceans, which is 71 percent of Earth’s area, to rise so much in that short a time, “that’s huge,” said University of Colorado climate scientist Kris Karnauskas. “That’s an incredible departure from what was already a warm state to begin with.”

Climate scientists have been talking about the warming on social media and amongst themselves. Some, like University of Pennsylvania’s Michael Mann, quickly dismiss concerns by saying it is merely a growing El Nino on top of a steady human-caused warming increase.

It has warmed especially off the coast of Peru and Ecuador, where before the 1980s most El Ninos began. El Nino is the natural warming of parts of the equatorial Pacific that changes weather worldwide and spikes global temperatures. Until last month, the world has been in the flip side, a cooling called La Nina, that has been unusually strong and long, lasting three years and causing extreme weather.

Other climate scientists, including National Oceanic and Atmospheric Administration oceanographer Gregory C. Johnson, say it doesn’t appear to be just El Nino. There are several marine heat waves or ocean warming spots that don’t fit an El Nino pattern, such as those in the northern Pacific near Alaska and off the coast of Spain, he said.

“This is an unusual pattern. This is an extreme event at a global scale” in areas that don’t fit with merely an El Nino, said Princeton University climate scientist Gabe Vecchi. “That is a huge, huge signal. I think it’s going to take some level of effort to understand it.”