July was the hottest month for the world's oceans in almost 130 years of record-keeping.

The average water temperature worldwide was 17 Celsius, 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 in the Pacific.

 

July was the hottest month for the world's oceans in almost 130 years of record-keeping.

The average water temperature worldwide was 17 Celsius, 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 in the Pacific.

Meteorologists said there is a combination of forces at work: A natural El Nino weather pattern just getting started on top of worsening manmade global warming, and a dash of random weather variations. Already the resulting ocean heat is harming threatened coral reefs. It also could hasten the melting of Arctic sea ice and help hurricanes strengthen.

The phenomenon is most noticeable near the Arctic, where water temperatures are as much as 5.5C 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 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."

The effects of that warm water already are being seen in coral reefs, said C. Mark Eakin, co-ordinator 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. Typically, bleaching occurs after weeks or months of prolonged high water temperatures. That usually means September or even October in the Caribbean Sea, said Eakin. He found bleaching in Guam on Wednesday. It is too early to know whether the coral will recover or die. Experts are "bracing for another bad year," he said.

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