Oceanographers have said that there are signs the Gulf Stream is warming and shifting its path closer to the North American coast, and that this is proof of climate change.
A new paper published in the popular science journal Nature Climate Change, collated some 25,000 temperature and salinity readings over 22 years from the ocean current, which flows from the Gulf of Mexico and Caribbean northeast past the US, Canada and Greenland to the Norwegian ea.
The study was led by physical oceanographers Robert Todd and Alice Ren from the Woods Hole Oceanographic Institution (WHOI).
"The warming we see near the Gulf Stream is due to two combined effects," Todd argued. "One is that the ocean is absorbing excess heat from the atmosphere as the climate warms. The second is that the Gulf Stream itself is gradually shifting towards the coast."
The scientist noted that the greatest temperature increase was seen in the ocean layer nearest the surface, which warmed by around 1° centigrade over the past two decades.
"One of the triumphs of this paper is that it provides observational confirmation of something that numerical simulations have predicted in a warming climate," Todd stressed.
The study took data from the Argo program, a network of 4,000 sensor floats that drift across the ocean while descending to up to 2,000 meters before rising to the surface, along with autonomous Spray underwater "glider" craft which the team launched from the Florida coats every two months.
"It can be difficult to make predictions about a current like the Gulf Stream using numerical modeling," said Ren, the other lead author. "Our paper is important in that it provides observational details about our changing weather and changing climate."
The Gulf Stream significantly influences temperatures in the far North Atlantic, keeping Britain and Ireland much warmer in winter than continental climates at similar latitudes in Canada or Russia.
Some climatologists have warned that global warming could weaken the current, ironically leading to colder weather in the North Atlantic region. But one study has found that the Gulf Stream was actually getting stronger and warmer, heating the Arctic in the process.