The shutdown of the North Atlantic Current could occur within one or two decades, potentially leading to summer heatwaves of 50°C and winter frosts of -30°C in Hungary. Freezing temperatures could appear anytime during summer, while we may also experience peak temperatures of 25°C during winter. Moreover, the current significant, temporary slowdowns are already having a serious impact on Hungary’s weather and our wallets.
The current weakens, and with the disappearance of its heating and cooling effects, it is a physical inevitability that our region will be dominated by the most extreme – and often chaotic – continental climate. If we are curious regarding the future weather of Budapest, it is worth taking a look at the climate of Kazan, the capital of Tatarstan. We discussed the reasons and details with meteorologist László Molnár, an expert at Kiderül.hu, who believes that the shutdown is becoming increasingly certain, with only its timing in question.
What is this current?
The AMOC (Atlantic Meridional Overturning Circulation) is a global aquatic conveyor belt, so to speak, the northern hemisphere’s gigantic “heat exchange system” in the Atlantic Ocean. Acting as a vast oceanic river, it transports warm water from the equatorial coasts of Africa to the Gulf of Mexico, then follows the American coastline northward. Its longest branch reaches as far as northern Scandinavia and southern Greenland. It is truly immense — the combined discharge of all the world’s rivers would make up only 1-2% of this current.
The entire system is driven by the laws of physics, specifically the balancing of thermal energy between the warm south and the cold north. As the water moves northward, it gradually releases its thermal energy into the atmosphere, cools down, sinks, and then flows back southward beneath the surface. Without getting lost in the details, it is the northernmost branch of the AMOC, known as the North Atlantic Current, that ensures that a west-to-east, so-called zonal flow remains dominant in Western and Central Europe. It does so by carrying water still warmer than its surroundings.
By maintaining this westerly flow, the AMOC warms the region in winter and cools it in summer, while also preventing extreme weather conditions caused by north-to-south, so-called meridional waves. These waves bring Arctic cold far south and push southern warmth far north
– explains the meteorologist to 24.hu.
Nowadays, it is almost impossible to define “average weather”, so let’s put it this way: before climate change turned everything upside down, Europe’s weather was influenced by zonality about 80% of the time, while meridional patterns accounted for the remaining 20%. In recent years and decades, however, this ratio has shifted significantly towards the latter, also apparent in the frequency of weather extremities.
The reason for this is the continuously fluctuating but trend-wise weakening flow of the North Atlantic Current. László Molnár has examined the details and consequences of this phenomenon.
Have we passed the tipping point?
One of the effects of rising average temperatures and frequent heat extremes is that the Greenland ice sheet is melting at an accelerating rate. In the island’s southern regions, large quantities of cold meltwater are flowing into the ocean, creating the phenomenon known as the “North Atlantic cold blob”, also clearly visible from satellite images. Meanwhile, the laws of physics remain unchanged: the AMOC’s warm, salty water sinks beneath the cold freshwater, cools down and consequentially slows, reducing the volume of water it transports. Overall, the current weakens and can no longer reach as far north.
As mentioned earlier, the AMOC’s flow rate is highly variable, averaging between 15 and 20 million cubic metres per second. However, over the past two decades, a measurable trend of decline has emerged, with a reduction of 17–18%. The real danger lies in the fact that beyond a certain loss of volume, the system reaches what is known as the tipping point, where its stable equilibrium is disrupted, shifting into another, unpredictable state — from which point a full shutdown could occur within a short period.
Some researchers believe that the tipping point could be triggered by a slowdown of just one million cubic metres per second. A 2023 study projects the complete collapse of the AMOC to occur sometime between 2025 and 2095, with the most likely timeframe being the 2050s.
Strangely, in recent years, there has been no publicly available information on the current flow rate of the AMOC. However, the accessible data suggests that the long-term slowdown has already exceeded two million cubic metres per second. In other words, we may have already crossed the tipping point, and from now on, total collapse may only be a matter of time. It is important to note that the exact moment of passing the tipping point can only be confirmed retrospectively, once the consequences become evident. Based on a comparison of the latest publications on the subject and his own research findings, meteorologist László Molnár believes:
No clouds, warming oceans
There is yet another crucial human factor that remains difficult to quantify precisely today but is certainly playing a significant role in slowing down the AMOC. As is widely known, mitigating the effects of climate change requires a radical reduction in the amount of carbon dioxide released into the atmosphere, the vast majority of which comes from burning fossil fuels. However, combustion — specifically the burning of coal and oil used as fuel — also releases aerosols into the air, such as soot and sulphur dioxide.
Sulphur dioxide, in particular, is highly harmful to both the environment and human health. However, these substances also have a cooling effect on the Earth’s surface. Firstly, they reflect some of the Sun’s energy, and secondly, by attracting moisture, they contribute to cloud formation — essentially acting as a form of “shading”. We previously covered this topic in detail.
For our discussion, it is sulphur dioxide (SO₂) that is of particular interest, especially in light of a regulation introduced at the beginning of 2020 that drastically reduced the sulphur content in marine fuel. As a result, emissions dropped to one-seventh of their previous levels. The North Atlantic, particularly the busy shipping routes between the United States and Europe, sees a constant flow of massive container and passenger ships. The pollutants these vessels emitted — most notably sulphur dioxide — previously aided significantly in limiting the warming of the oceans’ surface.
In recent years, however, this effect has disappeared, leading to a sudden spike in sea surface temperatures. This has reduced the temperature contrast between equatorial and polar waters — in other words, the energy that drives the AMOC. Ultimately, this has contributed to a decline in the current’s flow rate
– explains the expert.
Even colder winters
The impact of AMOC’s slowdown or shutdown on weather is generally understood to unfold over decades. Assuming that all processes occur gradually, forming a new system over time – which indeed takes a long while – this seems to be true. However, when László Molnár juxtaposed past episodes of extreme slowdowns and brief shutdowns with Europe’s weather patterns, he noticed temporary, yet immediately occurring effects.
The first significant slowdown — at a rate of ten million cubic metres per second — occurred in December 2010, causing an 8°C negative temperature anomaly across much of Europe. In Hungary, this led to a massive Christmas snowstorm, with the national average temperature dropping by more than 15°C in just two days. A similar event happened in March 2013, with a deviation of -10°C from the average, leading to a sudden, severe snowstorm in Hungary — one that many may still remember. Near-repeats of this occurred in March 2018, January 2021, and January 2022, and the list goes on. The most recent slowdown triggered the coldest period of this winter in mid-February, and there are even cases where a temporary weakening of the AMOC led to heatwaves in summer. These effects can also be observed in daily weather data for Budapest.
During critical AMOC slowdowns — within a few days — Budapest consistently experiences colder-than-average temperatures
– the expert emphasises. He adds that while other factors (such as the sudden weakening of the polar vortex) can also cause temperature drops, there has never been an instance where the current significantly slowed without a corresponding temperature decrease in Budapest. This means that much of the cooling effect from AMOC’s slowdown appears not over decades but within days, directly influencing domestic temperature records — and, consequently, heating and cooling costs.
If AMOC data is analysed separately based on its tempering effects — distinguishing between its winter cooling and summer heating impact, rather than averaging them out over the entire year—the figures show a 30% consistent slowdown during the October–April period, while in summer (May–September), the slowdown remains below 15%.
Precise calculations for Budapest show that when AMOC’s flow rate drops below 15 million cubic metres per second, the average winter temperature begins a consistent downward trend. If it falls below ten million cubic metres per second, it effectively cancels out the warming effect of global climate change during winter. In this scenario, AMOC’s influence on temperatures surpasses that of all other global weather factors combined.
Even hotter summers
In summer, the slowdown is more modest, not exceeding 15 per cent during the examined period. The reason for this is logical: Greenland’s ice melts gradually from May to September, with the melting reaching its peak at the end of summer. The meltwater trickles down to the seas slowly, meaning it takes time to accumulate and appear as a replenishment of the aforementioned cold blob. In other words, the melting process that occurs in summer exerts a stronger effect in winter.
In summer, the AMOC’s slowdown means that the westerly flow weakens, the ocean’s cooling effect is less pronounced, and moist oceanic air masses find it harder to reach our country. Due to the weaker slowdown in summer, temperature anomalies are also smaller, and the whole situation is more erratic. Nevertheless, a key figure can still be observed:
Not an ice age, but extremes
A widely held belief suggests that a total shutdown of the AMOC would trigger a new ice age in Europe despite rising global temperatures. However, this would, at most, affect Scandinavian countries, the United Kingdom, and the northwestern third of Russia. Even there, it would not necessarily mean the return of permafrost, just significantly colder conditions. As we can see from the figures above, however, the current has no need to stop entirely for its effects to be felt — both physically and financially.
The slowdown is already impacting our daily lives. Over the past 15 years, significant slowdowns of the current have led to numerous extreme weather events across Europe, including Hungary. Every Hungarian household has already had to pay tens – if not hundreds – of thousands of forints in the form of higher heating bills or increased prices for vegetables and fruit due to extreme weather conditions caused by the weakening of the AMOC.
In the Carpathian Basin, the shift has been much more towards extremes — freezing winters and scorching summers. Without the ocean’s cooling and heating effects, the region will experience a purely continental climate, similar to Kazakhstan or the already mentioned Tatarstan, located at the geographical border between Europe and Asia. It will take decades for the North Atlantic to cool completely, but when that happens,
Hungary will face winter temperatures below -30 degrees Celsius and summer highs reaching 50 degrees Celsius. At the same time, weather extremes will intensify: winter days (sub-zero temperatures) could occur in summer, while summer days (with highs above 25 degrees Celsius) could appear in winter
– the meteorologist explains.
All of this will happen because, first, the ocean will no longer be able to exert its warming and cooling effects, and second, the western airflow will disappear, allowing more frequent and stronger meridional waves to penetrate our region. Without the westerly flow, we must also prepare for severe droughts, as we will no longer benefit from the familiar “moisture-rich oceanic air masses”.
To conclude: how can we act to counter the process? Unless we can stop Greenland’s ice cap from melting, the ocean from warming, and put an end to excessive greenhouse gas emissions — there is nothing we can do. The only option left is adaptation, and the sooner we start, the better.
