The Gulf Stream at its weakest in 1,600 years: European climate at risk
Environment — di Andrea Barolini
Two studies published by Nature confirm the slowing of the Gulf Stream, which ensures a temperate climate in the North Atlantic.
The Gulf Stream at its weakest in 1,600 years: European climate at risk
Two studies published by Nature confirm the slowing of the Gulf Stream, which ensures a temperate climate in the North Atlantic.
The circulation of ocean currents in the Atlantic, which is fundamental to regulating the climate at a planetary level, has undergone a historic deceleration. It is in fact at its lowest levels in the past 1,600 years: a phenomenon due, at least in part, to global warming and climate change. This is explained by two studies published in the scientific journal Nature, which confirm the theory of a slowdown that began a very long time ago.
The slowing of the Gulf Stream driven by ice melt
In particular, the results indicate that the currents were relatively stable between the year 400 and 1850. Then, precisely when the industrial era began, the flow started to diminish in intensity. This reduction in the speed of the currents known by the acronym Amoc (Atlantic meridional overturning circulation) is in fact a consequence of the melting of the Arctic ice cap and glaciers in mountains around the world, which in turn cause fresh water to pour into the seas, especially in the North Atlantic. In this way – David Thornalley of University College London explained to the Afp agency – "the Amoc current weakens because mixing prevents the water from becoming dense enough to sink to the ocean floor."
New research led by UC London and WHOI provides evidence that a key cog in the global #ocean circulation system hasn’t been running at peak strength since the mid-1800s and is currently at its weakest point in the past 1,600 years. @NSF_GEO #NSFfunded bit.ly/2qps2bm
"Climate from the United States to the Sahel at risk"
The permanent ocean circulation consists in a rise of warm waters in the tropical zones of the Atlantic towards the north, carried by the Gulf Stream. This ensures a temperate climate for the whole of western Europe (and beyond). Once the water reaches the more northerly parts of the ocean, it progressively cools, becomes denser and heavier, sinks to the ocean floor and heads back southwards.
According to the Woods Hole Oceanographic Institution, which contributed to the studies on the phenomenon, "if the mechanism continues to slow down, this could disrupt weather conditions from the United States to Europe, as far as the Sahel, as well as accelerating the process of sea level rise, especially along the eastern coast of America." But this is not the only consequence of the change in pace of the Amoc: there is also a risk that the capacity of the oceans to store CO2 will be affected — the main gas responsible for global warming. The concentration of which in the atmosphere could thus increase further.