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Global sea surface temperatures rose sharply in March and continued to rise during much of April and oceanographers and climate scientists are watching with trepidation.
“There has been a striking increase in sea surface temperatures,” said Robert Rohde, lead scientist for Berkeley Earth. “We have above average temperatures nearly everywhere in the ocean.”
Sea surface temperatures rose to a higher level than ever observed for the same time period in March and stayed there for more than a month, he said.
Record high temperatures in the ocean are further evidence of a warming world where increasing greenhouse gas emissions are forcing an artificial increase in temperatures on top of natural variations in climate, scientists say. Warmer oceans have detrimental impacts on marine life and coastal ecosystems and drive extreme weather patterns, additional ice melt and rising sea levels.
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Meanwhile, global surface temperatures for the first three months of the year were the fourth warmest in 174 years, 1.87 degrees above the last century average, according to the National Oceanic and Atmospheric Administration.
Combined, the land and sea temperatures are especially concerning given the potential for an El Nino to develop this summer, Rohde said. El Nino, a pattern of warmer than normal temperatures in the Pacific Ocean along the equator, has a tendency to heat things up more than average.
If a strong El Nino does develop, there’s “a substantial chance that this could be a record warm year,” he said. “It’s less than 50% but it’s not trivial.”
‘Extremes are the new normal’
The rise in sea surface temperatures this year is particularly unusual because we’re coming off a 3-year La Nina event, which is typically a cooler period, scientists said.
The La Nina dissipated earlier this year and the ocean along the equator in the eastern Pacific is transitioning to a neutral status, and temperatures in the Central Eastern tropical Pacific are increasing, said Boyin Huang, a physical scientist and oceanographer with NOAA’s National Centers for Environmental Information.
The biggest question is what future months will look like if and when the forecast El Nino appears later in the summer. Could it be as strong or stronger than the record-breaking El Nino of 2015?
The highest global sea surface temperatures were recorded during a strong El Nino in 2015 and 2016, Huang said.
While the rise in sea surface temperature anomalies is terrifying, it’s not unexpected, Jens Terhaar, a postdoctoral scholar at Woods Hole Oceanographic Institution, tweeted this week. “This wouldn’t have happened without climate change, we are in a new climate state, extremes are the new normal.”
Will El Nino appear?
There’s not enough confidence yet for anyone to say for certain whether an El Nino will form or how strong it could be if it does form, Huang said. For now, an assessment from the Climate Prediction Center puts the chances of an El Nino at 60%.
“We still have six months to go,” he said.
The warm pool now off the coast of western South America would have to shift westward, Rohde said. “It’s not guaranteed that it will actually spread out and develop into a true El Nino.
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But the current situation feels very much like a transition period on the way to an El Nino, he said.
The surprising bump in global sea surface temperatures came on “suddenly and strongly,” Rohde said. “This level is something we don’t expect to see typically.”
That’s what leads him to expect a “very strong (El Nino) event,” he said. But it’s too soon to say for certain, he said.
“How much warmth are we going to get if we really get a proper El Nino?” he wondered. “We could be heading up from here and here is already very warm conditions.”
Global surface temperatures
Land surface temperatures also saw increases over the winter and early spring, NOAA reported.
- The March average global surface temperature was the second highest for the month since records began in 1850.
- March was the 529th month in a row with temperatures above the 20th century average.
- Global sea ice reached its second-smallest extent since records began in 1979.
- It was the fourth warmest January – March on record.
Sea surface temperatures off the Northeastern US
In recent months, temperature gauges and satellites have shown a high average temperature anomaly in what Huang describes as a small area of the Atlantic Ocean off the Northeastern U.S. coast.
In some areas on March 15, sea surface temperature were 22 degrees Fahrenheit higher than the average between 1970-2000.
Warmer waters in the Gulf of Maine
Here’s what the Gulf of Maine Research Institute reported on the Gulf of Maine sea surface temperatures.
- They were the warmest since satellite records began
- In February, temperatures reached as high as 4.11 degrees above the long-term average.
- All five of the warmest winters on record have occurred since 2015.
- Overall sea surface temperatures have risen at a rate of .81 degrees per decade since 1982.
- Wintertime temperatures in the Gulf are rising at 4 times the rate of the global ocean.
What’s the outlook for the rest of the year?
Conditions are increasing the chances of 2023 being “one of the warmest years,” Rohde said.
If this year isn’t a record warm year, many climate scientists say a continuing El Nino would make it very likely that 2024 will be even warmer than 2023.
Dinah Voyles Pulver covers climate, environment and weather issues for USA TODAY. She can be reached at dpulver@gannett.com or at @dinahvp on Twitter.
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