March 26, 2015
Scientists are warning that the gradual but surely-increasing Greenland ice sheet melt, caused by greenhouse gases, is causing the Gulf Stream to circulate at a slower rate.
Man-made global warming is seen as the link between the thinning and disappearance of ice around the world, writes The Guardian.
Scientists warn that further weakening in the Earth's ozone layer from chlorofluorocarbons, refrigerants, and carbon pollution will cause worldwide ice melts - and more water in our oceans.
Effectively - further melting Greenland ice sheet would advance the desalinization of currents - having a dire effect on the already changing weather systems.
Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research released a study on oscillations of the North Atlantic Current, published in the latest issue of the journal Nature Climate Change.
According to Rahmstorf, areas in the North Atlantic have been decreasing in temperature during the last 100 years, while regions in other parts of the world have recorded temperatures rising at an exponential rate.
He stated previous research has indicated that the slowness of the North Atlantic oscillation and circulation could be the reason behind this finding.
Rahmstorf explained he has found evidence that the global current has most definitely been weakening since the beginning of the 20th century, increasing its impact since 1970.
Scientists have only taken measurements of ocean temperatures from the surface, therefore, the long-term measurements of direct ocean currents are lacking.
However, by using only sea surface temperature readings and atmospheric changes to surmise the rate of Gulf Streamchanges, scientists have been led to believe that the cause was solely to blame on temperature variations in the North Atlantic - below the polar ice cap.
Rahmstorf used data collected from ice cores and lake and ocean sediments in order to figure out what these temperatures would have been millennia ago.
He and his team found that since the year 900 A.D., the changes in temperatures had been extraordinary, leading the team to determine that the change in the Gulf Stream is undoubtedly caused by man-made global warming.
According to Jason Box, a researcher at the Geological Survey of Denmark and Greenland, freshwater making its way into the North Atlantic Current is disturbing the normal ocean circulation.
And this is causing differences in water density.
From the south - warm, lighter water flows toward the north, where colder, heavier water sinks towards the lower depths of the ocean and flows back south.
Salinity levels in the water can also effect these factors.
Ice melts releasing large quantities of fresh water into the ocean affect equilibrium levels of salt and fresh water in the ocean - and this is what is causing a slow-down effect in the world's ocean oscillation cycles - like the Gulf Stream, which is slowing down in conjunction with these fluctuations.
Michael Mann, a researcher at Penn State University, stated common climate models are grossly underestimating the changes in the Gulf Stream, which he attributes to insufficient sea surface temperature data.
"They do not properly account for Greenland ice sheet melt," he said.
Rahmstorf believes that if the Atlantic overturning continues to slow, the Gulf Stream will also become weaker, negatively affecting marine ecosystems.
This will largely affect coastal settlements reliant on fisheries as their main source of income.
Large coastal metropolises like New York City will be victim to massive flooding from the stark rise in sea levels from more water being put into the ocean from the Greenland ice sheet.
It is possible that the Gulf Stream could be destroyed altogether - a tipping point that could mean the end for the well-being of Earth.
Courtesy to
http://www.designntrend.com/articles/45443/20150326/gulf-stream-weakening-as-greenland-ice-sheet-thins.htm