Ireland is infamous for its mild and wet climate. The main reason for this is the Gulf Stream which is part of a world-wide network of ocean currents. This particular current originates in the middle of the Atlantic Ocean near the equator at the Gulf of Mexico and transports warm water in a north-east direction across the Atlantic where it is known as the Gulf Stream or the North Atlantic Current. Further north, after losing much of its heat, it is called the Norwegian Current and North Cape Current.
Ireland is the first land mass it encounters after its journey. Ireland is also the first and main beneficiary of the Gulf Stream effect. The heat that is carried by the current is released into the air which raises the average temperature way above what would be normal for this latitude. This becomes especially evident if winter temperatures are being compared: The average temperatures for November and December in Labrador, Newfoundland and Quebec on the other side of the Atlantic are between -10 degree and -20 degree Celsius. In Ireland any kind of frost is a rarity and most of the time the temperature is even in the positive double figures. In summer the difference is less extreme but still noticeable.
Over the past decades however questions have been raised on how climate change will influence the global network of ocean currents including the Gulf Stream. In order to work properly the sea water needs a certain salinity and temperature. Now that ocean temperatures are rising and melting ice sheets adding fresh water to the oceans the status quo is rapidly changing. According to the latest studies the Gulf Stream has already slowed down some 15% and is now at its slowest in 1000 years.
Because much of how these currents work is still a mystery the future is uncertain. Many scientists however believe that the gulf stream and other currents will not just slow down over time but that there will be a complete shutdown once a tipping point has been reached. In theory the consequences for Ireland could be extreme. The best-case scenario would be a change in seasonal weather patterns, cool summers and extremely cold winters. Some scientists believe that glaciers could develop and even that northern Europe could experience another ice age.
From earth history we know that it is possible. A break in the current 950.000 years ago triggered a series of ice ages. Some 13.000 years ago a weakening of the current caused a 2000 yearlong cold spell known as the Younger Dryas. Those cooling events are all linked to a preceding rise in global temperatures and glacial freshwater entering the oceans. It seems like it is history repeating itself only this time we know the reason for the global warming trend.
Carsten Krieger, December 2019