“Conveyor” slows down. Will Europe and North America be covered with ice?
The German climatologist published a study, during which he came to the conclusion that in the near future the network of global ocean currents will slow down to critical levels. This will inevitably affect the climate in Europe and America, but it can respond to weather disasters and crop failures in any corner of the Earth.
“The system can collapse”
As you know, the weather in Europe is “made” by cyclones coming from the North Atlantic: they bring air heated by the Gulf Stream, whose thermal power is comparable to the power of one million nuclear power plants. That is why the climate of the Old World is so mild. The remnants of this heat also reach Russia: thanks to the North Atlantic Current, which is a continuation of the Gulf Stream, Murmansk remains an ice-free port.
And the Gulf Stream itself is part of the Atlantic Meridional Reversible Circulation (AMOC) – a system of currents that carries tropical heat to the north and Arctic cool to the south. True, cold water moves in depth, closer to the seabed, because it is heavier than warm water. Thus, the system of currents resembles a conveyor belt, which is still twisted into a figure eight. Its role in the formation of the climate is enormous: AMOC not only “warms” Europe, but is also responsible for the redistribution of heat energy throughout the World Ocean and the Earth's atmosphere. Figuratively speaking, this is the kitchen of the weather for the entire planet, but especially for the Northern Hemisphere.
Scientists have been talking for a long time that the “conveyor” slows down and that not everything is in order in the “kitchen”. So, in 2018, a study was published in the journal Nature – it showed that the speed of the Gulf Stream has decreased for 150 years and now the current has become 15% weaker than it was in the middle of the twentieth century.
And now a new scientific work. Climatologist Niklas Boers of the Postdam Institute for Climate Impact Research argues that the Atlantic meridional reversible circulation has suffered “an almost complete loss of stability.” The current system has become as weak as it has not been for the last thousand years, and this trend is unlikely to stop. After analyzing how the temperature and salinity of ocean surface waters have changed since the end of the 19th century, the scientist comes to the conclusion that the slowdown in AMOC is not a natural decline, but a sign of global changes. His work is published in the journal Nature Climate Change.
“The data obtained confirms that the decrease in the circulation of the Atlantic currents, most likely, means approaching a critical threshold, beyond which this system can collapse, – says Niklas Boers. “And it will happen earlier than we originally thought. Stopping circulation will inevitably lead to serious consequences and catastrophic changes in the weather around the world. “
What are these consequences? The researcher lists: rising sea levels, cooling and powerful storms in the Northern Hemisphere, as well as anomalies associated with rainfall. They threaten Africa, South America and India with crop failures. Given the low standard of living and the high population in these regions of the planet, it is possible to predict with 100% accuracy a series of social explosions and humanitarian disasters.
The consequences for the ecology and biosphere of the Atlantic Ocean will also be sad. They may not strike our eyes, but they will affect, for example, fish catches.
Two-level junction turns into a traffic jam
The Earth's climate is complex and full of paradoxes. The planet is warming, but sometimes at the height of summer we have to put on autumn twists (as was the case in July 2019, which became the coldest for Moscow in 70 years of meteorological observations). Ice is melting in the Arctic (its area has decreased by more than 25% since 1970), and there are more and more ice around Antarctica. From time to time, ice blocks the size of European cities break off from the same Antarctica, but the mass of its cap as a whole is growing.
Stopping the circulation of ocean currents is from the same series of climatic paradoxes, because it turns out that warming should lead to a cooling. Let's explain this mechanism on the fingers.
Because of warming, the Arctic ice is melting, first of all – the giant Greenland glacier, which is the second largest after the Antarctic one. Since melt water is always fresh, it dilutes sea water and makes it less salty. Siberian rivers make their contribution, and considerable, to the desalination of the Arctic waters. Over the past decades, their flow into the Arctic Ocean has increased (this is also a consequence of global warming), and river water, as we remember, is also fresh.
What happens? As already mentioned, cold water in the Atlantic “conveyor” moves in depth, because it is heavier than warm water. But if you dilute it with melt and river water before that, it will no longer strive to the depths, since (let's recall physics again) fresh water is lighter than salt water! As a result, the warm Gulf Stream flowing to the north collides with cold masses of water moving to the south, and they no longer “dive” under it, as before. The two-level interchange turns into a traffic jam – all traffic slows down.
This model was analyzed in the early 1990s by Aleksey Karnaukhov, Candidate of Physical and Mathematical Sciences. He calculated that the stop of the Atlantic currents threatens the onset of another ice age, which will make life in Europe impossible.
“There have been such stops in the past. Temperatures in Europe dropped by 20 ° C, and the glacier reached the territory of what is now eastern Ukraine. It happened that the Gulf Stream stopped for a year, – says the scientist. – We see that now the climate is hot and cold. I compare it with a car – when it starts to stall, it also does not stop immediately, but goes jerkily. I believe that all these oddities of the weather are harbingers of the coming cataclysm. A new ice age awaits us. It will hit Canada and the countries of Northern and Central Europe hardest of all – there, due to a severe cold snap, the population will have to be evacuated. Russia and Southern Europe will not suffer so much, although the situation will be critical in some regions too.
While the Gulf Stream warms Europe, the warm Kuroshio Current performs a similar function in the North Pacific. It goes around three of the four largest islands in Japan, warming them, and then turns east and moves towards North America, turning into the North Pacific Current. There is even an opinion that California owes its mild favorable climate to Kuroshio. At the same time, like the Gulf Stream, in the north this current meets the colder one, which “dives” under it – the Kuril.
Several years ago, Professor Talgat Kilmatov, Professor of the Pacific Oceanological Institute of the Far Eastern Branch of the Russian Academy of Sciences, Doctor of Physics and Mathematics, applied a mathematical model to two occurring currents and came to similar conclusions: the melting of Arctic ice can lead to the fact that the cold stream of the Kuril Current will become more fresh and less dense. In this case, it will slow down the Kuroshio and disrupt the circulation of currents in the Pacific Ocean. Surely this will cause a cold snap in Japan, and possibly in North America.
I must say that not all scientists share the disastrous forecasts regarding the stopping of the Gulf Stream and the coming glaciation of Europe. In their opinion, the reason for the apocalyptic versions and scenarios (including, by the way, for the Hollywood blockbuster “The Day After Tomorrow”) was the use of an idealized, simplified mathematical model. In the 1990s, when this hypothesis arose, climatology did not rely on as much data as it does now. In fact, everything is much more complicated: too many parameters need to be taken into account when studying the Earth's climatic system, there are too many nonlinear relationships between them.
But this only suggests that further research is needed. Scientists are not Hollywood scriptwriters. The simplistic approach does not suit them.
