‘Surprise’ Ocean Heat Waves Are Becoming More Common
Environmental News

‘Surprise’ Ocean Heat Waves Are Becoming More Common

Illustration for article titled 'Surprise' Ocean Heat Waves Are Becoming More Common

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There are two flavors of surprise: good and bad. Winning the lottery? Good. Extreme heat waves cooking the oceans with more regularity, ruining fisheries that millions of people rely on? Decidedly bad.

Yet that’s our present predicament, one that’s likely to get worse as the oceans heat up even further. A new study released in the Proceedings of the National Academy of Sciences on Monday shows that climate change is already pushing large portions of the oceans outside their normal bounds, resulting in what the authors call “surprise” conditions that can wreak havoc on fisheries and the livelihoods associated with them. Climate change could further push ecosystems outside their limits, forcing the people who rely on them to adapt or suffer the consequences.

To undertake their study, researchers dug into annual temperature data for 65 large marine ecosystems collected since 1900. They then compared a given year to the 30 years preceding it, basically making a running average of “normal” conditions. Years where the temperature was two standard deviations warmer (or colder) than the preceding 30 years was dubbed a “surprise.” The two standard deviation mark is also dubbed a “significant” threshold in science, but surprise is a much more common way to think about it.

“I wondered what would happen if you allow the reference points to shift as new information comes in,” Andrew Pershing, the chief science officer at the Gulf of Maine Research Institute who led the study, told Earther. “This led us down a path toward thinking about how ecosystems and people will adjust to warmer conditions, and what rate of change will be really stressful.”

The results show a dramatic upswing in surprising years since the 1980s, particularly in the Arctic and Atlantic. Those surprises are largely of the hotter-than-normal variety. Only four cold surprises have occurred since 2000. The pace of hot surprises appears to have accelerated since 2010 in the Pacific and Indian oceans as well. T

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