When a 43-foot gray whale was sighted off the Israeli town of Herzliya last year, scientists came to a concluded that It must have crossed the normally icebound route above Canada, where warm weather briefly opened a clear channel three years earlier. Below the ocean's surface, scientists have found plankton in the North Atlantic where it had not existed for at least 800,000 years.
The whale's odyssey and the surprising appearance of the plankton indicate a migration of species through the Northwest Passage, a clear sign of how global warming is affecting animals and plants in the oceans as well as on land.
"The implications are enormous. It's a threshold that has been crossed," said Philip Reid of the Alister Hardy Foundation for Ocean Science in Plymouth, England. "It's an indication of the speed of change that is taking place in our world in the present day because of climate change," he added in a telephone interview Friday.
Reid said the last time the world witnessed such a major incursion from the Pacific was 2 million years ago, which had "a huge impact on the North Atlantic," driving some species to extinction as the newcomers dominated the competition for food.
Changes in the oceans' chemistry and temperature could have implications for fisheries, as species migrate northward to cooler waters, said Katja Philippart of the Royal Netherlands Institute of Sea Research, who is coordinating the project funded by the European Union.
"We don't say whether it's bad or good. We say there is a high potential for change," she said.
The Northwest Passage, the route through the frigid archipelago from Alaska across northern Canada, has been ice-free from one end to the other only twice in recorded history, in 1998 and 2007. But the ice pack is retreating farther and more frequently in summer.
Plankton that previously had been found only in Atlantic seabed cores from 800,000 years ago appeared in the Labrador Sea in 1999 -- and then in massive numbers in the Gulf of St. Lawrence two years later. Now it has established itself as far south as the New York coast, Reid said.
The endangered gray whale sighted off the Israeli coast in May 2010 belonged to a species that was hunted to extinction in the Atlantic by the mid-1700s.