A blob of cold water appeared in the North Atlantic Ocean following a summer marked by warmer-than-normal temperatures and this has scientists concerned.

Although the world seems to be heating up, data from the National Oceanic and Atmospheric Administration (NOAA) show that sea water in a region south of Greenland and Iceland is seeing historically low temperature. The cold temperature is in contrast with high temperatures observed in most parts of the world.

Researchers assured that there is no mistake in the data because the colder area is highly populated with buoys and is along an observable shipping line.

Although there is no definitive answer that could explain the existence of this blob, scientists think it is associated with the slowing of circulation in the Atlantic Ocean.

In a paper published in Nature Climate Change in March, a team of scientists argued that a massive ocean current, the Atlantic Meridional Overturning Circulation (AMOC), is weakening.

The water's salinity and temperature differences power AMOC, but the sudden infusion of a layer of cold water can weaken the circulation. Cold freshwater is likely to remain on the surface since it is less dense and thus, floats on the denser water of the ocean.

Researchers speculate that the cold water comes from glacial melt water from Greenland, which currently loses over a hundred billion tons of ice per year, a phenomenon largely blamed on global warming.

Researchers said that the amount of fresh water that flowed from Greenland into the Atlantic increased significantly from 1970 to 2000.

Research conducted by Leon Hermanson, from the Met Office Hadley Center in Exeter, and colleagues suggests that the northward flow of warm water and the southward flow of deep and cold water have slowed down by up to 20 percent during the 20th century.  

Study researcher Michael Mann said he was initially skeptical about the idea that a "conveyor belt" circulation pattern of the ocean could be abruptly weakened due to global warming.

"Yet this now appears to be underway, as we showed in a recent article, and as we now appear to be witnessing before our very eyes in the form of an anomalous blob of cold water in the sup-polar North Atlantic," Mann said.

Hermanson said that strong winds over the Atlantic also likely contributed to the current blob.

"The current 'blob' was caused partly by strong winds over the Atlantic during the winter 2013-14 taking a lot of heat out of the ocean," Hermanson said. "I think there are longer-term changes going on in the Atlantic that would give a similar temperature pattern."

Photo: Lt. Cmdr. Ken Wasson/Released | Flickr