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A new study warns that weakening ocean currents in the North Atlantic could trigger colder, harsher winters across Europe, echoing conditions last seen during the Little Ice Age. Scientists say the subpolar gyre’s instability since the 1950s could reshape Europe’s climate, though not all experts agree.
Europe, future with a freezing winter? The study and the scenario
Europe grappling with extreme cold in the future? The hypothesis of a kind of ‘ice age’ is put forward by a study that analyzes the evolution of ocean currents in the North Atlantic. The North Atlantic subpolar gyre, highlights the study published in Science Advances, plays a decisive role in ensuring the passage of heat towards the northern hemisphere.
The gyre interacts with a more extensive network of ocean currents within the Atlantic Meridional Overturning Circulation (AMOC) system. According to the research, which analyzed oxygen and carbon isotopes present in the shells (Arctica islandica and Glycymeris glycymeris) of the North Atlantic Ocean, the polar gyre has been progressively losing stability since the 1950s and it cannot be ruled out that this trend will continue in the coming decades, with consequences for the climate.
The picture is defined as “very worrying” by researcher Beatriz Arellano Nava, from the University of Exeter in the United Kingdom, to Live Science. “The subpolar gyre has recently been recognized as a determining element; we still need to better understand the impacts of its sudden weakening. But what we know so far, thanks to the few published studies, is that” a further weakening “would lead to more extreme weather events, particularly in Europe.”
The most extreme scenario is linked to a possible collapse of the entire AMOC system, which however – according to the study – is not a plausible hypothesis. The eventual collapse of the subpolar gyre would have a lesser impact but “even if the consequences would not be as catastrophic as those of an AMOC collapse, the weakening could have substantial climatic consequences. The subpolar gyre can weaken abruptly without the AMOC collapsing: this is what happened during the transition to the Little Ice Age between the 13th and 14th centuries.”
The scenario presents elements attributable to one of the coldest periods ever recorded in the Northern Hemisphere, with an average temperature drop of 2 degrees and extremely harsh winters in Europe and North America. Researchers recall that in the past, the phenomenon would not have been triggered solely by the subpolar gyre, which would nonetheless have played a significant role in the overall picture. The data collected through the analysis of shells allowed for the reconstruction of the gyre’s evolution over the last 150 years, identifying two main phases of instability: the first can be placed before the 1920s, the second is ongoing. According to the researchers, in essence, a loss of stability in the gyre would trigger climate changes.
In the scientific community, however, there are dissenting opinions. “The data sets are very useful because they are very well dated and allow for understanding year-by-year climate changes,” says David Thornalley, professor of oceanography and climatology at University College London, not involved in the study, to Live Science.
“However, the analysis did not directly link the patterns observed in the shell data to the physical characteristics of the ocean, nor did it provide a solid basis for a change in the way the subpolar gyre operates. I am skeptical of this interpretation.”
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