Ireland could face more severe winter storms, more rapid sea level rises and cooler year-round temperatures if the Gulf Stream collapses.
The dip in temperatures would most likely be reversed by longer-term global warming, but the combined effect of the two processes leaves much uncertainty ahead.
That is according to Dr Levke Caesar, a geographer at Maynooth University, responding to the latest study on the Gulf Stream, more properly called the Atlantic Meridional Overturning Circulation (AMOC), which found it is experiencing an almost complete loss of stability.
The AMOC is the system of Atlantic Ocean currents that carries warm waters from the tropics to the north and returns colder waters southward.
It influences weather globally because of how it helps regulate temperatures in the air masses above it and how they in turn distribute rains.
A study from the Potsdam Institute for Climate Impact Science in Germany shows the circulation has lost so much strength that it could stop working completely.
The problem is attributed to human-caused climate change, with global temperature rise warming seas in some parts while glacier melt dumps vast amounts of extra cold water in other parts.
Dr Caesar was lead author on another study earlier this year that showed the AMOC was slowing and weakening but she said she was surprised how disrupted and unstable the Potsdam study found it.
I didnt expect that. The author confirmed that we are getting closer to the tipping point, I already knew that, but he suggests we are closer than we thought, she said.
The scientific community expected that the AMOC would most likely not tip if we stay below two degrees of warming, but this study doesnt confirm that.
It doesnt say it will tip below two degrees, but it really shows there is already a lot of instability going on, so we are less reassured than before.
Dr Caesar said she did not anticipate any major short-term impact.
Because the system is an ocean system, its slow to react, so even if we pass the tipping point, it would take a few decades to collapse, she added.
She said the combined impact of an AMOC collapse and global warming made the outcome harder to predict.
But if the collapse would happen within the near future, then we would very likely get a net cooling in the North Atlantic and definitely in Ireland.
Then, depending on how much carbon dioxide we continue to emit to the atmosphere, some time, probably, the influence of global warming will win.
Theres one study which suggests that the storminess over the North Atlantic, especially the storm tracks coming towards Western Europe, so Ireland and Great Britain especially, would be more enhanced so we would have more severe winter storms.
But we need more research because theres not that much known about the effects, especially in combination with global warming.
Also, Ireland has kind of a special position. The AMOC is this large-scale ocean circulation in the North Atlantic and, for Ireland, there are more local currents like the European slope current which flows along it and we need to understand more how these currents influence each other.
The Potsdam study, by Dr Niklas Boers, which was published in the journal Nature Climate Change, draws on more than a century of ocean temperature and salinity data to show significant changes in eight indirect measures of the AMOCs strength.
These indicators suggested that the AMOC was running out of steam, making it more susceptible to disruptions that might knock it out of equilibrium, Dr Boers, said.
If the circulation shuts down, it could bring extreme cold to Europe and parts of North America, raise sea levels and disrupt seasonal monsoons that provide water to much of the world.
Ireland could face more severe winter storms, more rapid sea level rises and cooler year-round temperatures if the Gulf Stream collapses.
