The planet is on course to experience one of its warmest years on record, but scientists have been left baffled by a massive cold patch in the North Atlantic Ocean.
The area, which lies just to the south of Greenland and Iceland, is showing some of the coldest temperatures ever recorded for the region.
It comes at a time large parts of the world are experiencing some of the hottest on record, raising fears the recent ‘pause’ in global warming has come to an end.
Yet researchers fear the Atlantic blob, as it is being called, may be a sign of something more worrying taking place out in the ocean. They believe accelerated melting of the enormous ice sheet covering Greenland is dumping record amounts of cold fresh water into the ocean.
Recent research has also shown that the system of ocean currents which includes the Gulf Stream, known as the Atlantic Meridional Overturning Circulation, may be slowing down at an alarming rate. It found the enormous current, which circulates warm water from the equator north and carries cold water from the Arctic south, has slowed by 15-20 per cent over the past century. Combined this may be leading to abnormally cold temperatures in the northern part of the ocean. The latest data released by the National Oceanic and Atmospheric Administration showed this is occurring at a time when global temeratures are 1.51°F (0.84°C) above average. August itself has been one of the warmest on record.
In a statement the NOAA said: ‘Near record to record warmth engulfed much of the global land and ocean surface throughout the first eight months of 2015, resulting in the highest January–August period on record at 0.84°C (1.51°F) above the 20th century average. ‘This value exceeded the previous record set in 2010 by 0.10°C (0.18°F). ‘The average temperature for South America and Asia was the highest since 1910, with Europe and Africa having a top five warm year-to-date.
THE GULF STREAM SLOWDOWN
The Gulf Stream is a powerful current that forms part of the North Atlantic meridional overturning circulation. This is a system of currents that are driven by the rising and sinking of water in different regions of the Atlantic.
However, research published in March this year showed it is now slowing down at the fastest rate seen in around 1,000 years.
The study shows that the circulation of warm and cold water around the Atlantic Ocean has slowed by 15-20 per cent over the past century.
Scientists say that the increasing flow of fresh water from melting Greenland ice sheets may be driving the slowdown.
The findings suggest that as global temperatures rise due to climate change, areas that are warmed by the Gulf Stream could see temperatures fall, particularly in the winter.
‘Near-average to much-cooler-than-average conditions was present across eastern North America, northern parts of the Atlantic Ocean and parts of the southern oceans.’
Climate scientists are now working in an attempt to better understand the cause of the abnormal cold blob in the North Atlantic and the impact it will have.
This year is expected to experience a particularly strong El Nino which may help to explain some of the high temperatures seen in the Pacific.
Dr Michael Mann, a climatologist and director of the Earth System Science Center at Pennsylvania State University, was part of the team that showed the current circulation in the Atlantic Ocean has been slowing down at a rate not seen in the past 1,000 years.
He told the Washington Post: ‘We now appear to be witnessing before our very eyes in the form of an anomalous blob of cold water in the sub-polar North Atlantic.
Professor Stefan Ramhmstorf, an oceans physicist at the Potsdam Institute for Climate Impact Research, added that if the addition of cold fresh water from the Greenland ice sheet contributed to the slow down of the Gulf Stream system the effects could be ‘substantial’
He said: ‘Disturbing the circulation will likely have a negative effect on the ocean ecosystem, and thereby fisheries and the associated livelihoods of many people in coastal areas.
‘A slowdown also adds to the regional sea-level rise affecting cities like New York and Boston.
‘Finally, temperature changes in that region can also influence weather systems on both sides of the Atlantic, in North America as well as Europe.’