(CN) — The Arctic Ocean began getting warmer more than a century ago, according to new research showing that the polar ecosystem began experiencing the effects of climate change much earlier than existing records suggest.
The study, published Wednesday in the journal Science Advances, suggests that the warmer and saltier waters of the Atlantic Ocean began encroaching into the Arctic at the beginning of the 20th century, triggering the rapid warming that melts sea ice and raises sea levels. Researchers call this process Atlantification. The study’s authors say methods of tracking this process through instruments like satellite measurements have not captured the full scope of this Atlantification.
“We used deep sea marine records to get a longer geological context of Atlantification in the gateway of the Arctic Ocean,” said Francesco Muschitiello, the study’s co-lead author and a lecturer in physical geography at University of Cambridge, in an interview.
Muschitiello noted that in roughly half a century of using methodologies like satellite data, scientists have firmly established significant warming in recent decades. He said his research was aimed at painting a broader picture of the changing Arctic waters across decades and centuries.
“We talk a lot about variability extremes in climate weather events, talking about annual, inter-annual timescales,” said Muschitiello. “We don’t really have the records that allow us to get a good understanding of how the climate varies over long timescales.”
According to a statement accompanying the study, the results “provide the first historical perspective on Atlantification of the Arctic Ocean.” Muschitiello and his colleagues used geochemical and ecological data from ocean sediment to reconstruct 800 years of estimated changes in water temperature and salinity. They uncovered a connection between the North Atlantic and the Arctic that is much stronger than previously thought.
“When we looked at the whole 800-year timescale, our temperature and salinity records look pretty constant,” Tommaso Tesi, the study’s co-lead author from the Institute of Polar Sciences of the National Research Council in Bologna, said in the statement. “But all of a sudden at the start of the 20th century, you get this marked change in temperature and salinity — it really sticks out.”
Muschitiello said a “growing body of evidence” shows that rapid warming began shortly after anthropogenic, or human-related, forces like greenhouse gas and pollution levels skyrocketed towards the end of the 1800s.
“We always want to talk about climate and say the temperatures have been going through the roof in the last few decades and that’s when climate warming has kicked in, but that’s not true,” Muschitiello said. “The onset of Atlantification in the Arctic [that we found] lines up fairly well, a few decades after the onset of the Industrial era.”
The Arctic Ocean, the world’s smallest and shallowest ocean, is already warming at a rate double the rest of the globe, Muschitiello said. The polar region is especially vulnerable to the worst effects of climate change. He said the findings raise interesting questions about how climate change is affected by the past, present and future.
With the onset of Atlantification occurring much earlier than initially understood, Muschitiello said the wider lens on the progress of Atlantification could help researchers pinpoint the causes of Arctic Ocean warming even more definitively by allowing them parse through natural and anthropogenic factors.
“Is the climate system more sensitive to greenhouse gases than we previously thought? If you start looking at these geological records, then you get a bigger picture and you change your understanding of the driving forces behind it,” Muschitiello said.
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