The winter of 2014-15 was one of the warmest in recorded history as per National Oceanic and Atmospheric Administration. However there is one region in the North Atlantic which is contrary to the trend seen in other parts of the ocean. The phenomenon is also consistent right since 1970.
The particular spot in the North Atlantic has shown temperatures which are to 3.6 degrees Fahrenheit colder than average. According to a recent study, the cold patch could be one of the indicators of a dramatic slowdown in the Gulf Stream. It is a worrying situation since the Gulf Stream moves huge amounts of heat north from the equator to the pole, passing off the East Coast of the U.S. and into the North Atlantic.
This could add credence to the theory put forth by experts that global warming could trigger so-called “tipping points” in the climate system, which, once started cannot be stopped. Recently the U.N. Intergovernmental Panel on Climate Change has opined that there is a 10% likelihood of a Gulf Stream shutdown before year 2100. Some experts say that the likelihood of such a scenario is still higher.
Co-author Stefan Rahmstorf, a climate scientist at the Potsdam Institute for Climate Impact Research in Germany, in a blog post for RealClimate said, “Evidence is mounting that the long-feared circulation decline is already well underway. Evidence is mounting that the long-feared circulation decline is already well underway.”
The slowdown of the Gulf Stream as the study finds is unprecedented in hundreds perhaps thousands of years. Another tipping point could be the melting of the Greenland ice sheet. The process brings forth a huge influx of freshwater from the ice sheet. It is also one of the main sources of freshwater inflow into the North Atlantic Ocean.
As the fresh water, which lighter and colder than heavier salty water pours into the area, it tends to sit on top of the water column. Accumulating over the years, it interferes with the formation and sinking of dense, cold and salt-enriched waters. This in turn slows the Gulf Stream and affects the ocean circulation downstream as well.
The rapid slowdown of the Gulf Stream can increase sea level rise rates along the highly populated Mid-Atlantic and Northeast coasts of the U.S. It could also precipitate much colder conditions than the normal in the northern parts of Europe and America.