Fragments of a melting iceberg in Scoresby Fjord, Greenland, in August 2023. A group of scientists has issued a warning about the possibility that rising temperatures and melting icebergs disrupt to the Atlantic Meridional Overturning Circulation, the dominant heat transport mechanism to North Atlantic. The effects of a severe disruption could potentially threaten the viability of agriculture in northwestern Europe. (Olivier Morin – AFP / Lehtikuva)
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A GROUP of climate scientists and oceanographers have sounded alarm about the risk of a consequential change in the Atlantic Meridional Overturning Circulation (AMOC), the dominant mechanism of heat transport in the North Atlantic.
The Gulf Stream is one tentacle of the circulation, which determines life conditions for all people in the Arctics.
In an open letter submitted to the Nordic Council of Ministers in October, the researchers drew attention to a string of scientific studies that suggest that the risk has been “greatly underestimated” despite what would be a “devastating and irreversible” impact especially on the Nordics.
“Major cooling in the region while surrounding regions warm,” the letter reads.
Powered by the sinking of saltier, denser water and rising of fresher, lighter water, the circulation has already been shown to have slowed down – possibly by what is known as the cold blob, a cold temperature anomaly in surface waters in the North Atlantic. Meltwater from Greenland is feared to expand the blob, stalling the circulation and upending precipitation and temperature patterns in and outside Europe.
“While the impacts on weather patterns, ecosystems and human activities warrant further study, they would potentially threaten the viability of agriculture in northwestern Europe,” the scientists warned.
“The high-risk event would be the circulation stalling,” Petteri Uotila, a physical oceanographer at the University of Helsinki, elaborated in an interview with Helsingin Sanomat on 25 October.
“If it stalls, which to be clear is the most extreme risk, winter temperatures would decrease by dozens of degrees. We’d be in Siberia,” he added. “The risk is substantial, but we don’t yet know whether the worst will happen.”
The impacts would likely be felt across the globe, scientists emphasised. Tropical rainfall belts could shift, oceanic carbon dioxide uptake could be reduced, marine ecosystems and fisheries could be upheaved, and sea-level rise could accelerate especially along the Atlantic coast of the Americas.
The Intergovernmental Panel on Climate Change (IPCC) estimated last year that there is a “medium confidence” that the circulation will not collapse abruptly before 2100, but added that the scenario would “very likely” cause an abrupt shift in regional weather patterns and large-scale impacts on ecosystems and human activities.
The letter warns that in light of recent research the panel “underestimated the risk” as the passing of this tipping point is a “serious possibility” already in the next few decades.
The scientists underscored that adaptation is not a viable response option to such a severe climate catastrophe. The Nordic Council of Ministers should thus assess the regional risks and take steps to minimise them, including by leveraging the region’s international standing to add pressure for greater urgency and priority in the global effort to reduce emissions as quickly as possible to stay close to the 1.5-degree target set forth in the Paris Agreement.
“Tipping point risks are real and can occur within the 1.5–2°C climate range of the Paris Agreement,” they said, reminding that the world is currently on track for over 2.5°C of heating.
“Even with a medium likelihood of occurrence, given that the outcome would be catastrophic and impacting the entire world for centuries to come, we believe more needs to be done to minimise this risk.”
Aleksi Teivainen – HT
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Source: www.helsinkitimes.fi
