New researched published in the most recent edition of the scientific journal PNAS has shown that there have been significant and drastic changes to oceanic currents in the western North Atlantic Ocean since the 1970s.
The research found that the influence of the cold water Labrador Current has been decreasing continually since the 1970s, minimizing the impact made by a cold water current interacting with a warm water current. This change has taken place at approximately the same time as the global warming phenomenon and is entirely unique in the past two millennia.
The international team of researchers used geochemical methods to prove that a drastic change in the western North Atlantic Ocean took place in the early 1970s, coinciding with changes laid at the feet of global warming.
The researchers examined deep sea corals that live hundreds of metres below the sea’s surface. The corals record in their own biomass the different nitrogen isotopic signatures which are carried by water currents, and in partnership with their growth rings, provide scientists a detailed and accurate reconstruction of the oceanic current ratios over the last few decades.
The coral showed that there had been a clear reduction of the stable nitrogen isotopes 15N und 14N since 1970 which indicates that the cold Labrador Current is becoming less important in the western North Atlantic Ocean.
Any possible alternative to the reason for this chance were able to be excluded thanks again to the nitrogen isotopes within the coral. The nitrogen isotope signatures of the amino acids showed that the food chain played no significant role since the 1970s.
Isotopic analysis of fossilized deep sea coral from the same region allowed the researchers to identify a longer timeline, which showed that there had been no significant change up until the 1970s in the previous 2000 years.
The researchers suspect a correlation between the changes in the ocean currents and anthropogenic climate change.
Source: Swiss Federal Institute of Acquatic Sciences and Technology
Image Source: Copyright: O.A. Sherwood, Memorial University of Newfoundland, Canada