Swordfish and jellyfish thrive in warm N. Atlantic

Parts of the North Atlantic are setting winter heat records, allowing species ranging from swordfish to jellyfish to thrive beyond their normal ranges in a shift linked by many scientists to global warming.

Temperatures in Arctic waters off northern Europe at the tail end of the Gulf Stream, for example, are about 6.7 Celsius (44.06 Fahrenheit), the highest for early January since records began in the 1930s, according to Norway's Institute of Marine Research.

The world's oceans are already in a warming trend that could alter fish stocks, perhaps damaging coral reefs that are vital nurseries for tropical species while boosting northern stocks of cod or herring.

"The global oceans have been warming since the middle 1970s and several studies have shown that the warming can be attributed to a human-produced signal," said James Hurrell of the U.S. National Center for Atmospheric Research.

Off New York this week, rescuers guided eight dolphins into open water after they became stranded in a shallow cove, apparently because unusually warm waters meant fish on which they feed were staying closer to the coast.

A type of Black Sea jellyfish seems to have become established off Scandinavia, perhaps flushed out of the ballast tanks of visiting ships and now able to survive because of less chilly waters in winter.