Did the Atlantic circulation collapse as early as 2025? Will the "day after tomorrow" of humanity come| Global Ecosystem | AMOC Collapse

The 100 meter tsunami swept through New York, and the world entered a period of glaciers... If you are a movie fan, you must have been deeply impressed by the scenes in the American disaster film "The Day After Tomorrow". The cause of these abnormal climates in the film is the complete collapse of a global ocean current system called the Atlantic Meridional Overturning Circulation. Although the plot of the movie is a bit exaggerated, the risk of AMOC collapse is by no means sensational, and the latest research suggests that this time may even come early.

On the 25th, the journal Nature published the latest findings from a research team at the University of Copenhagen in Denmark. Research shows that AMOC may collapse by the middle of this century, or even as early as 2025. This conclusion is more pessimistic than the United Nations assessment. Once AMOC collapses, it will have a huge impact on the global ecosystem and affect every villager on Earth.

"Heating Stove" and "Heat Storage Tank"

If given an analogy, AMOC is like a huge global conveyor belt. It transports warm tropical and southern hemisphere ocean surface waters to high latitude regions, causing these waters to cool, sink, and flow southward in the cold North Atlantic.

This circulation process is crucial for many aspects of the Earth's climate system, especially for heating Northwest Europe. It is therefore also known as the world's most important natural heating system.

In addition to "sending warmth" to high latitudes, studies in recent years have also found that AMOC can transport ocean surface heat to the deep sea for storage, which can buffer surface warming. It can be described as a natural "heat storage".

It can be seen that AMOC has a powerful function in regulating the global ecosystem. But it is also fragile because with global warming, this "conveyor belt" is at risk of being shut down.

Scientists have found through multiple observations that this circulation system has been slowing down over the past 100 years, especially since 1970. The current circulation is weaker than at any time in the last century or even the previous millennium.

One of the main causes of conveyor belt failure may be the accelerated melting of Greenland's ice sheet caused by global warming. The melting of ice caps dilutes nearby seawater, and a decrease in seawater salinity slows down sinking, thereby disrupting normal circulation. Some people believe that AMOC is becoming the Achilles heel of the global climate system.

Warning of the Achilles Heel

In fact, the world is not indifferent to this Achilles heel, and many professional institutions have issued warnings.

An international team of scholars from universities in countries such as the UK, Switzerland, and the US released a report in 2016, which identified the AMOC anomaly as one of the five climate "critical points" that could be triggered by sustained carbon emissions.

A 2019 report by the United Nations Intergovernmental Panel on Climate Change predicts that AMOC will weaken in this century, but it is unlikely to completely collapse before 2100.

And this time, the Danish research team has clearly come to a more worrying conclusion than the United Nations. The team analyzed North Atlantic sea surface temperature from 1870 to 2020 and used it as an indicator of AMOC. These records trace back much longer than directly measuring AMOC and can provide more reliable information on temperature trends.

The team has identified early warning signals for the critical transformation of AMOC, indicating that the earliest possible point of its end or collapse could be 2025, and no later than 2095. The most likely point of collapse is between 2039 and 2070.

Will the day after tomorrow come?

What will the world face if AMOC really closes?

CNN reported that the collapse of the Atlantic meridional flipping circulation has occurred. As early as more than 12000 years ago, the rapid melting of glaciers caused the circulation to malfunction, and the temperature in the northern hemisphere experienced huge fluctuations of 10 to 15 degrees Celsius within 10 years.

The Daily Mail of the UK wrote that after the end of the so-called "Little Ice Age" in 1850, the flow of AMOC decreased, leading to a cooling in Europe. At that time, the Thames River was completely frozen, and records showed that Londoners walked across the river. If AMOC collapses again, not only will winter in Europe become colder, but summer droughts, storms, and heatwaves will also become more common.

The USA Today newspaper reported that this collapse could trigger rapid weather and climate changes in the United States, Europe, and other regions. Cities such as Boston and New York in the United States are expected to experience rising sea levels, and more severe hurricanes will appear along the east coast of the United States.

In addition, as ocean currents weaken and heat storage functions decline, the global greenhouse effect may become more pronounced and trigger other ecological "critical points".

Many scientists have stated that the exact critical point of AMOC collapse is not clear, and measurements of circulation have only shown minor evolutionary trends to date. But they unanimously believe that the new research results are worrying and call for effective measures to save energy and reduce emissions, and to slow down the destructive effects of Arctic glacier melting on AMOC.