(AP) Steve Kramer spent an hour and a half swimming in the ocean Sunday — in Maine. The water temperature was 72 degrees — more like Ocean City, Md., this time of year. And Ocean City's water temp hit 88 degrees this week, toasty even by Miami Beach standards.
Kramer, 26, who lives in the seaside town of Scarborough, said it was the first time he's ever swam so long in Maine's coastal waters. "Usually, you're in five minutes and you're out," he said.
It's not just the ocean off the Northeast coast that is super-warm this summer. July was the hottest the world's oceans have been in almost 130 years of record-keeping.
The average water temperature worldwide was 62.6 degrees, according to the National Climatic Data Center, the branch of the U.S. government that keeps world weather records. That was 1.1 degree higher than the 20th century average, and beat the previous high set in 1998 by a couple hundredths of a degree. The coolest recorded ocean temperature was 59.3 degrees in December 1909.
Meteorologists said there's a combination of forces at work this year: A natural El Nino system just getting started on top of worsening man-made global warming, and a dash of random weather variations. The resulting ocean heat is already harming threatened coral reefs. It could also hasten the melting of Arctic sea ice and help hurricanes strengthen.
The Gulf of Mexico, where warm water fuels hurricanes, has temperatures dancing around 90. Most of the water in the Northern Hemisphere has been considerably warmer than normal. The Mediterranean is about three degrees warmer than normal. Higher temperatures rule in the Pacific and Indian Oceans.
The heat is most noticeable near the Arctic, where water temperatures are as much as 10 degrees above average. The tongues of warm water could help melt sea ice from below and even cause thawing of ice sheets on Greenland, said Waleed Abdalati, director of the Earth Science and Observation Center at the University of Colorado.
Breaking heat records in water is more ominous as a sign of global warming than breaking temperature marks on land, because water takes longer to heat up and does not cool off as easily as land.
"This warm water we're seeing doesn't just disappear next year; it'll be around for a long time," said climate scientist Andrew Weaver of the University of Victoria in British Columbia. It takes five times more energy to warm water than land.
The warmer water "affects weather on the land," Weaver said. "This is another yet really important indicator of the change that's occurring."
Georgia Institute of Technology atmospheric science professor Judith Curry said water is warming in more places than usual, something that has not been seen in more than 50 years.
Add to that an unusual weather pattern this summer where the warmest temperatures seem to be just over oceans, while slightly cooler air is concentrated over land, said Deke Arndt, head of climate monitoring at the climate data center.
The pattern is so unusual that he suggested meteorologists may want to study that pattern to see what's behind it.
The effects of that warm water are already being seen in coral reefs, said C. Mark Eakin, coordinator of the National Oceanic and Atmospheric Administration's coral reef watch. Long-term excessive heat bleaches colorful coral reefs white and sometimes kills them.
Bleaching has started to crop up in the Florida Keys, Puerto Rico and the Virgin Islands — much earlier than usual. Typically, bleaching occurs after weeks or months of prolonged high water temperatures. That usually means September or October in the Caribbean, said Eakin. He found bleaching in Guam Wednesday. It's too early to know if the coral will recover or die.
Experts are "bracing for another bad year," he said.