World's ocean temps are warmest on record

updated 5:47 p.m. ET Aug. 20, 2009

WASHINGTON - 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. June was only slightly cooler, while August could set another record, scientists say. The previous record was set in July 1998 during a powerful El Nino weather pattern.

At a full degree above the 20th century average of 61.5 degrees, "the global ocean surface temperature for July 2009 was the warmest on record," the center said.

Large portions of many continents had substantially warmer-than-average temperatures, the center stated.

"The greatest departures from the long-term average were evident in Europe, northern Africa, and much of western North America," according to the National Oceanic and Atmospheric Administration, which oversees the center. "Broadly, across these regions, temperatures were about 4-7 degrees F above average."

El Nino, emissions as factors
Meteorologists said there's a combination of forces at work: A natural El Nino system just getting started on top of worsening man-made carbon emissions tied to 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.

"Arctic sea ice covered an average of 3.4 million square miles during July," the center said. "This is 12.7 percent below the 1979-2000 average extent and the third lowest July sea ice extent on record, behind 2007 and 2006."

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."

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