Some experts are concerned that the destruction of the North Atlantic Current might result in a warming of Europe. In the past, eight thousand years, this has already occurred.
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| The Gulf Stream map |
The North Atlantic Current, a component of the Gulf Stream, may disappear in the course of the 21st century, possibly as early as 2025, according to a scientific article that made it to the front page of the newspapers last week. The article was written by the Danish research couple Peter and Susanne Ditlevsen.
A cold snap throughout Europe might result from such a collapse, with unpredictable effects. Actually, since the 1950s, the Gulf Stream has been deteriorating.
Warm, salty water from the Gulf of Mexico is pumped northeastward by the Atlantic Meridional Overturning Circulation (AMOC) into the Barents Sea, where it descends owing to the creation of sea ice, becomes heavier, and then flows back several thousand meters into the Caribbean Sea. The thermohaline cycle, which generates warmer precipitation than low-salinity water and subsequently rains down over the continent, is responsible for Europe's mild temperature.
The power used by the AMOC, which is equivalent to nearly one million nuclear power plant blocks, is 1.5 trillion watts per second. The thermohaline cycle, named from the Greek words for "warm" and "salt" Low-salt water does not create warmer precipitation, which subsequently falls down over the mainland.
Now, this temperate European environment is in danger if the flow of warm, salty water from the south is obstructed. This is the situation, for instance, when fresher water—such as meltwater—keeps entering the North Atlantic. The polar ice and the Greenland mainland ice have been melting more quickly for years due to man-made climate change.
By reducing the salt content of the water coming in from the south, the meltwater discharged in this way makes it less able to sink. In turn, this slows down the undersea reflux, allowing for a decrease in the amount of salt water that enters the Caribbean while increasing the amount of lower-salinity, colder meltwater that accumulates in the North Atlantic and produces cooler precipitation.
The climate of Berlin would ultimately resemble that of Newfoundland, while Naples would eventually have a climate similar to that of New York, if this evolution were to proceed linearly.
Exact same thing occurred roughly 8,200 years ago. The northern hemisphere dropped by 2 to 3 degrees Celsius in just a few decades, according to sediment and fossil analyses. The 8.2k event or the Misox fluctuation—based on related pollen analyses in the same-named valley in Switzerland—are terms used in study.
How did that come about? The late-glacial Lake Agassiz and Lake Ojibway were jolted into Hudson Bay by the disintegration of the Laurentide Ice Sheet, which had covered much of North America during the Weichselian-Würm Ice Age and released 100,000 cubic miles (164,000 cubic kilometers) of water into the North Atlantic.
The North Atlantic's salinity dropped, the temperature dropped, and a massive meltwater pulse abruptly raised the sea level. The 8.2k event, which is the fifth according to the official count, is referred to as the Bond event after the US geologist Gerard Bond because it was the result of warming and glacier melt during the Holocene.
The warm Atlantic era came to an end with the 8.2k race. This "meltwater pulse 1C" may have nonetheless played a role in the Holocene temperature Optimum (HCO) ending two to three thousand years later, even though the temperature warmed up again after around 100 years. According to studies, the global average temperature was 0.7 degrees Celsius higher during the HCO than it was from then on until the 19th century.
The sixth report from the Intergovernmental Panel on Climate Change (IPCC), whose final paper was released this March, makes the assumption that temperatures were warmer in the recent past than they are today with a moderate degree of certainty, though sometimes always for the northern hemisphere. It's conceivable that we are "only" now moving past the 8.2k cold relapse.
Colleagues including Niklas Boers from the Potsdam Institute for Climate Impact Research and Jochem Marotzke, Director at the Max Planck Institute for Meteorology in Hamburg, criticized the Ditlevsens' prognosis. The issue: The two Danes' estimates are based on modeling, which also takes into account the current situation and both the suspected repercussions, such as when and how severe a recurrence of the North Atlantic cold would occur.