Met Éireann has warned of significant potential climate changes to come in the future, resulting from the cooling of Atlantic temperatures caused by the collapse of the gulf stream tidal network.
The Atlantic Meridional Overturning Circulation (AMOC) is a large-scale system of ocean currents that circulates warm, salty water from the South Atlantic and the tropics, to the colder North Atlantic, via the Gulf Stream.
When these currents reach the north, the salt water cools and descends, migrating back down south to complete its cycle which can occur over a 1,000-year period.
According to Met Éireann, recent studies projected that the AMOC could decline by 30-40% by 2100, resulting in cooler North Atlantic sea surface temperatures, which will have a profound effect on the global ecosystem.
“AMOC weakening is expected to lead to additional sea level rise around Ireland,” Met Éireann added.
The stream also carries important nutrients critical to sustaining ocean life in the Atlantic and is a crucial factor in determining global temperatures.
Furthermore, experts at the Royal Meteorological Society said:
“This conveyor belt is essential for heat exchange between the ocean and the atmosphere – it releases heat into the atmosphere above the North Atlantic Ocean, then travels through the ocean, resurfacing in other areas of the world.”
Early warning signals from oceanographers indicate that the marine conveyor belt currently stands at a tipping point, with experts warning of a potential total collapse, or at the very least, a substantial deceleration of currents.
This would have far reaching effects on global weather systems, particularly for Ireland, given that our temperate climate is largely dependent on AMOC, which prevents extreme seasonal weather changes.
Studies by researchers in Europe and the U.S published in the science journal, Nature in January 2024 and July 2023, have used computer models to reconstruct AMOC over the years to illustrate the changes that have taken place, and have found that the currents have slowed by 15% since the 1950s.
“Our findings show that in recent years, the AMOC appears to have reached a new record low, consistent with the record low annual sea surface temperature in the subpolar North Atlantic since observations began in 1870,” the researchers reported.
“The AMOC decline since the mid-20th century is a feature projected by climate models in response to rising carbon dioxide levels,” researchers said.
One study points to global warming and the rise in greenhouse gas (GHG) emissions to account for the change in AMOC whereas, the other attributes it to the input of freshwater during the little ice age, which occurred between the fourteenth and nineteenth century.
“An AMOC shutdown would cause cooling of the northern hemisphere, sea level rise in the Atlantic, an overall decrease in precipitation over Europe and North America, and a southwards shift in monsoons in South America and Africa,” the UK’s Met Office also reported.
Tidal currents originate close to shores and are influenced by the phase of the moon, while surface currents are shaped by wind patterns.
Other, slower currents, like the gulf stream, form between the surface and the seafloor and are driven by changes in the ocean’s salt content and temperature, through a process known as thermohaline circulation.