Cold 'blob' on Atlantic surface may be disturbing sea currents
Published 27/09/2015 | 02:30
A giant 'blob' of cold water has appeared in the North Atlantic over the summer months, bucking the global trend of warmer-than-normal sea surface temperatures around the world, scientists have declared.
Sea temperatures off the Irish coast have been lower than in recent years, with a summer high of no more that 14.9C at best - perhaps a degree lower than usual.
Temperatures of the sea surface in a vast region south of Greenland are near to, or below their lowest recorded levels, leading some scientists to speculate that it may be a sign that the vast ocean currents of the North Atlantic are slowing down due to large volumes of glacial melt-water running into the sea.
Since the start of the year, scientists at the US National Oceanic and Atmospheric Administration have recorded much lower sea-surface temperatures than usual in the region south of Greenland and Iceland, with some areas recording the lowest eight-month period on record.
This contrasts with the noticeably higher-than-average temperatures seen in almost every other part of the world, which has coincided with a strong El Nino event in the Pacific Ocean - the warm sea current that is associated with a disturbance in normal weather patterns.
A spokeswoman for the Met Office said: "North Atlantic sea surface temperatures are well below average, they have been all summer."
One suggestion is that the freshwater run-off from the melting Greenland glaciers are disturbing the ocean "engine" that drives the North Atlantic meridional overturning circulation - the giant "conveyor belt" of sea currents that includes the Gulf Stream.
The engine that drives ocean currents is powered by the sinking of cold, salty water from the sea surface to the seabed in a part of the North Atlantic south of Iceland.
However, some scientists fear that it is being disturbed by a layer of cold freshwater, which tends to remain on the sea surface, because the less-dense freshwater floats on the denser, salty water.
Earlier this year, scientists published a study suggesting that the North Atlantic circulation - the northward flow of warm, surface water and the southward flow of deep, cold water - had slowed by 15pc-20pc during the 20th Century.