For the past 12 months, the world's sea surface temperatures have broken records every day.
Ocean scientists are increasingly concerned.
"It's not just an entire year of record-breaking ocean temperatures, but the margin by which they are exceeded - which is not even close to the previous record," said Brian McNoldy, senior research associate at the University's Rosenstiel School from Miami. of marine, atmospheric and earth sciences. "That's what raises many people's eyebrows."
According to the University of Maine's Climate Reanalyzer, average sea surface temperatures today are about 1.25 degrees Fahrenheit higher than they were between 1982 and 2011. It's a huge anomaly that could have significant impacts on weather and ecosystems.
Human-induced climate change likely plays a role, researchers said, but is unlikely to be the only factor. Climate models predict a steady rise in sea surface temperatures, but not so quickly. The surface temperature of the oceans also fluctuates and can be affected by natural climate variability, including patterns such as El Niño and La Niña.
Scientists do not yet know exactly why the sea surface temperature has risen so high.
"I pray that we will have a once-in-a-lifetime year of hot sea surface temperatures, but I worry that something else may be going on that is causing a long-term change in sea surface temperatures that we did not predict. " says John Abraham, a professor at the University of St. Thomas who studies ocean temperatures. "All bets are off now, this is something so unusual that it challenges our past expectations."
If ocean temperatures continue to break records, it could bleach corals, generate more intense and rapidly developing hurricanes, increase coastal temperatures and make extreme precipitation more likely - events that scientists have observed as early as 2023.
Temperatures rose to record levels for the first time in mid-March last year, according to the Climate Reanalyzer, which tracks average measurements of sea surface temperature data from around the world. The data used to measure these trends dates back more than forty years and comes from networks of monitoring buoys and robotic equipment designed to help meteorologists make weather forecasts.
Abraham suspects that the main cause of this trend is climate change, which also involves some natural ocean processes that are not yet well understood.
Average air temperatures today are roughly 1.8 F higher than they were between 1979 and 2000, but water has a greater ability to absorb and store heat; the ocean has absorbed about 90% of the heat created by global warming. So the seas were not expected to warm up that much.
"It takes a lot of heat to raise the temperature of the water," Abraham said.
However, he and McNoldy both acknowledged that it is possible that an ocean system has crossed a critical threshold due to global warming.
Last year, some scientists also pointed to El Niño, a natural pattern involving warm ocean waters in the tropical Pacific, as a factor driving up average sea surface temperatures.
But now that El Niño is disappearing, they suspect something else is going on.
"What we are seeing now as a result of high temperatures is something that goes beyond El Niño and cannot be explained by the arguments made six months or 12 months ago," Abraham said. "Sea surface temperatures are higher elsewhere and very far from El Niño locations."
McNoldy listed other dynamics that may play a small role, including the weakening of the North Atlantic trade winds, which has reduced the amount of dust blowing into North America from the African Sahara. Dust absorbs the sun's energy over the Atlantic Ocean, so it's possible that more radiation will be absorbed into the ocean.
"That could be a factor, but I don't have a good feeling about being able to quantify it," McNoldy said.
Some researchers have also suggested that changes in maritime shipping regulations may have reduced sulfur pollution in ship exhaust, ultimately reducing cloud cover and allowing the oceans to absorb more energy.
"All these little ingredients on their own don't explain what we're seeing, but maybe in a combined sense they do," McNoldy said, although he added that he's skeptical of the theory but can't rule it out.
Whatever the reason, higher sea surface temperatures can pose serious threats. Warmer water provides more energy for storms to feed on, so "the storms that form tend to get stronger," Abraham said.
Warmer waters also increase the risk of rapid intensification - when hurricane winds suddenly intensify as they approach the coast. Last year, Hurricane Idalia went from Category 1 to Category 4 in 24 hours.
Some of the largest sea surface temperature anomalies are in the Atlantic Ocean and off the Horn of Africa, where the hurricanes that batter the east coast of the United States often begin. Additionally, the National Weather Service's Climate Prediction Center says there is a 62% chance of a La Niña - which is associated with active and damaging hurricane seasons - developing in late spring.
"Not ideal for a quiet hurricane season," McNoldy said, noting that the extra warmth from the ocean could also extend the season.
High sea surface temperatures can also contribute to more intense rainfall on the coast, Abraham said, by helping build a moister and hotter atmosphere.
McNoldy said he's also concerned about corals, which took a hit last year.
Warm waters caused some of the worst bleaching events ever observed in Florida and the Caribbean Sea, turning stressed corals white and expelling the photosynthetic algae that live in their tissues.
"If the anomalies we are seeing now occur during the hot months, the oceans will be warmer than in 2023 and we will see even worse coral bleaching events," said McNoldy.
Among ocean scientists, he added, "We're all actually observing something strange. At some point someone will come up with an answer, but I haven't seen that answer yet."
This article was originally published on NBCNews.com