Climate Change: from the heart of the Ocean a new (and unexpected) answer

Her waters are also getting saltier. The smallest of the oceans began warming in the early 1900s, and its rate of warming is more than twice the global average.

The Arctic Ocean began warming decades earlier than previously thought - as early as the early 1900s. A research team led by the National Research Council (CNR) and the University of Cambridge has reconstructed the last 800 years of changes in this sea that play a key role in the study of global climate change. The analysis was published in the journal Science Advances. The Arctic is the smallest of the world's oceans and the shallowest, but it is also the one that is warming more than any other. "The rate of warming is more than twice the global average," said Francesco Muschitiello, of Cambridge University.

The Arctic Ocean Warming Process

Thanks to satellite observations, it has been identified that the Arctic Ocean is transforming for two reasons: not only are its waters warming, but they are also becoming saltier, in a phenomenon called "atlantification." This mechanism consists of a progressive intrusion of Atlantic waters, which are warm and salty, into the Arctic domain, which is instead cold and fresh.

"Arctic atlantification is progressively accelerating, however, prior to our study we did not have a historical view of this process, as satellite observations are limited to roughly the last 40 years. Instead, this water change preceded the warming documented by satellites and observational sites," explained Tommaso Tesi, first author of the study and researcher at CNR-Isp.

Research on Arctic Ocean Warming

For the study, the research team examined a region at the entrance to the Arctic Ocean, along the eastern part of the Fram Strait, between Greenland and Svalbard. Thesis pointed out that a sedimentary record was analyzed for signs of atlantification, such as changing temperature and salinity. From observations of "molecular signatures" on fossil sediments of marine microorganisms in the ocean depths, it was found that by the early 20th century, Arctic temperature had already increased by about 2°C, sea ice began to retreat, and salinity began to increase.

"When we examined the entire 800-year period our data on temperature and salinity were quite constant - said Tommaso Tesi - but suddenly, at the beginning of the 20th century, we observe a marked change in temperature and salinity". Although the causes that led to the anticipation of the atlantification phenomenon in the Arctic are still unclear, the results of the new research are fundamental for future simulation models of global climate change.

Recently, moreover, a huge hole was observed in the Arctic that formed suddenly, while on the top of Greenland rain fell for the first time since 1950.

Stefania Bernardini