Fossilized plankton is the first evidence that the 20th century Northeast Atlantic circulation was out of the ordinary.
A dramatic decrease in cold-water plankton during the 20th century was discovered. A sudden change happened after thousands of years of stability, according to a study funded by the National Science Foundation that was conducted at the Woods Hole Oceanographic Institution and other organizations.
The research was made public in the journal Geophysical Research Letters.
Some fossilized remains of plankton sampled from the Northeast Atlantic Ocean south of Iceland were analyzed, and the outcome was truly dramatic. A sudden change in the species that live in that area was observed.
The Northeast Atlantic is critical for Earth’s climate system and marine ecosystems.
The researchers noticed proof that Northeast Atlantic in the 20th century was abnormal in comparison to the previous 10,000 years.
That change provoked the cold, subpolar waters to be replaced by warm, subtropical waters around Iceland. That change drastically affected the evolution and distribution of marine life, particularly plankton.
The research is derived from earlier work that analyzed how the circulation in the North Atlantic was altered since the industrial era. The study was conducted on over 150,000 specimens of planktonic foraminifera, tiny single-celled creatures that inhabit ocean waters.
They compared how certain species of plankton behaved over a ten thousand year span. Sediment from the bottom of the ocean was used to reconstruct how the region evolved.
The region in the cause was full of plankton that preferred cold waters between 6,000 B.C. and A.D. 1750.
However, during the 20th century, the population of cold-water plankton declined and was slowly replaced by transitional, warmer-water plankton.
Steve Hovan, a program director in NSF’s Division of Ocean Sciences, said:
“Changes in one part of the system result in changes elsewhere. What’s significant about this study is that it shows just how rapid these responses can be.”