Atlantic current at its weakest in 1,600 years

Global warming may be responsible for the Atlantic Ocean’s northward current reaching its weakest strength for approximately 1,600 years, multiple studies suggest.

Research led by University College London (UCL) found that the global ocean circulation system hasn’t been running at its peak since the mid-1800s, including the Gulf Stream, which warms Western Europe.

A separate study from the Potsdam Institute for Climate Impact Research found that this has worsened rapidly since 1950 in conjunction with rising temperatures. It is thought that melting ice sheets and glaciers caused fresh water to begin the circulation slowdown at the end of the Little Ice Age in 1850, which has been exacerbated over the past 70 years. If this trend continues, it could result in a more rapid increase in sea levels on the east coast of North America, far more extreme winters in Europe, and also disrupt weather patterns in the African Sahel.

“What is common to the two periods of weakening – the end of the Little Ice Age and recent decades – is that both were times of warming and melting,” said UCL senior lecturer Dr David Thornalley.

“Warming and melting are predicted to continue in the future due to continued carbon dioxide emissions,” he added.

To investigate previous Atlantic Ocean circulation, the researchers examined the size of sediment grains deposited by deep-sea currents – the larger the grains, the stronger the current.

They found that its current has weakened by approximately 15%-20% in the past 150 years. This is thought to suggest a gap in current climate models, possibly because they do not consider active ice sheets or because more of the Arctic is melting than thought.