Portuguese 
English 
Spanish 
6 min of reading 
0 comments 
AMOC, the Atlantic Meridional Overturning Circulation, Is at Its Weakest Level in 1,000 Years and May Collapse in the Coming Decades, Affecting Rain in Brazil, Winters in Europe, and Global Climate.
There is an ocean current that no Brazilian learned about in school, but that determines how much it will rain in the Northeast, when drought will hit the North, and whether European winters will continue to be cold or turn into ice nightmares. It is called AMOC — Atlantic Meridional Overturning Circulation. And it is failing. In October 2024, 44 of the world’s leading experts in physical oceanography, climate modeling, and deep ocean circulation signed an open letter presented at the Arctic Circle Conference in Iceland.
The document stated, in a straightforward and technical manner, that the risk of AMOC collapse had been “vastly underestimated” by the IPCC, the Intergovernmental Panel on Climate Change of the UN. The warning indicated that the current could reach a tipping point in the coming decades, with potentially devastating and irreversible consequences for the global climate system. It was not environmental activism. It was a warning based on historical series, advanced numerical modeling, and observable physical evidence.
What Is AMOC and Why Does the North Atlantic Circulation Influence Brazil’s Climate
The AMOC is a central component of the planetary climate system. It is a large-scale ocean circulation that transports heat from the Southern Hemisphere and tropical regions to the North Atlantic. This mechanism works like a thermal conveyor belt.
-
100 times less energy consumption: the innovation that could solve the huge energy crisis of AI.
-
Scientists reveal a new method using solar light that transforms plastic into vinegar and could change the game against pollution, converting waste into a sustainable solution with future global impact.
-
3,500-year-old tear discovered reveals a textile technique much more advanced than previously thought in the Bronze Age.
-
One of the largest manufacturers of military ammunition in the world is Brazilian and has just signed an agreement with the Navy to develop national ammunition for the frigates built in Santa Catarina that will protect the Blue Amazon.
Warm, salty waters from the Tropical Atlantic move northward at the surface. When they reach latitudes near Greenland and Iceland, they release heat to the European atmosphere. This process is responsible for making the climate of Western Europe much milder than it would be at equivalent latitudes in Canada.
After losing heat, the water becomes colder and denser. At the same time, intense evaporation in the North Atlantic increases its salinity, making it even heavier.
This combination causes the water to sink to the deep layers of the ocean, forming what is known as Deep Water of the North Atlantic. This mass then returns southward through the depths, completing the cycle.
This system transports approximately 1 petawatt of energy per second, about 50 times the global human energy consumption. Without the AMOC, estimates indicate that Europe could be between 5°C and 10°C colder on average.
But the impact is not restricted to the Northern Hemisphere.
The position of the Intertropical Convergence Zone (ITCZ), the planet’s main belt of tropical rain, depends on the thermal balance between the North Atlantic and the South Atlantic. When the AMOC weakens, the North Atlantic cools relatively, displacing the ITCZ southward. This alters the rainfall regime in the Amazon and the Northeast of Brazil.
The potential outcome is:
- Reduced precipitation in the Amazon during critical seasons
- Alteration of the hydrological cycle in Northern Brazil
- More intense and concentrated rain in the Northeast
- Increased risk of out-of-season floods
In other words, a current in the North Atlantic directly influences Brazil’s water regime.
AMOC Weakening: Scientific Evidence Points to Its Weakest Level in More Than 1,000 Years
The direct measurement of AMOC only began in 2004 with the RAPID-MOCHA project, which installed a network of permanent sensors at a latitude of 26°N. Prior to that, scientists relied on climate proxies such as:
- Marine sediments
- Isotopes in ice cores
- Tree-ring growth
- Surface temperature reconstructions
In 2021, a study published in Nature Geoscience gathered 11 independent indicators covering 1,600 years of indirect records. The conclusion was clear: AMOC is at its weakest state in more than a millennium.
The slowdown began after the Little Ice Age, around 1850. However, the acceleration of the weakening coincides with the exponential increase in greenhouse gas emissions from the second half of the 20th century.
The main physical mechanism is the dilution of salinity in the North Atlantic.
The Greenland is losing approximately 250 billion tons of ice per year. This freshwater dumped into the ocean reduces surface density and hinders the sinking of water, a crucial step for maintaining active circulation.
In December 2025, researchers from the University of California, Riverside analyzed historical records of temperature and salinity and confirmed that the so-called “cold blob” — the persistent cold patch south of Greenland — can only be reproduced in models that include progressive weakening of the AMOC.
This “cold blob” is considered a physical signature of the ongoing collapse.
AMOC Tipping Point: When the Collapse May Happen According to Climate Models
In 2023, researchers from the University of Copenhagen applied statistical methods of complex systems to estimate the likely timing of the AMOC collapse.
The estimated window was between 2025 and 2095, with the most likely year being 2057. The study generated controversy for using simplified models.
However, in 2024, researchers from the University of Utrecht published in Science Advances a high-resolution simulation that explicitly resolves oceanic vortices. The model identified a consistent physical tipping point — a rupture point beyond which the circulation collapses irreversibly.
In 2025, Copenhagen updated its estimate to 2065 as the most likely year, while maintaining the risk window between 2037 and 2109.
It is not an exact prediction. It is a risk range that includes the current generation.
Climatic Impacts of AMOC Collapse in Europe and the Northern Hemisphere
Modeling published by van Westen and team shows that, after the collapse:
- London could record winter extremes close to -20°C
- Oslo could reach -48°C
- Expansion of sea ice in the North Atlantic
- Drastic reduction in average temperature in Northern Europe
This would occur simultaneously with ongoing global warming.
Professor Tim Lenton, from the University of Exeter, describes the scenario as an amplification of seasonality: much colder winters and hotter summers, increasing stress on energy infrastructure, transport networks, and agriculture.
Consequences of AMOC Weakening for Brazil and the Amazon
Models published in npj Climate and Atmospheric Science indicate that the weakening of the AMOC:
- Heats the Tropical Atlantic
- Displaces the ITCZ
- Alters atmospheric circulation over the Amazon
The International Institute for Applied Systems Analysis (IIASA), in 2025, estimated that each 1 Sv (million m³ per second) of weakening increases rainfall by 4.8% in the dry season of Southern Amazon.
But this increase does not compensate for the combined impacts of:
- Deforestation
- Regional warming
- Land use change
The structural risk remains high.
AMOC as a National Security Issue: Iceland’s Reaction
In November 2025, Iceland declared the risk of AMOC collapse as a national security issue. The government started strategic planning involving:
- Energy security
- Food stocks
- Port infrastructure
- Urban planning
The country adopted the precautionary principle: even a 25% chance is considered unacceptable for a systemic irreversible risk.
Climatologist Stefan Rahmstorf from the Potsdam Institute emphasizes that the problem is not absolute certainty, but the impossibility of ruling out a collapse within a still reversible timeframe.
Global Climate System and Irreversibility of Oceanic Circulation
AMOC is a nonlinear system with multiple equilibrium states. Paleoclimatic records show that during the last glacial period, circulation has already collapsed abruptly in less than a decade. Recovery took centuries.
Once crossed the tipping point, reversal may require radically different climatic conditions from the current ones. The conveyor belt of the Atlantic took about a thousand years to reach its current state. It may take centuries to return and if it returns.
And all of it depends on a delicate density difference that is being altered by 250 billion tons of annual meltwater from Greenland.
An invisible process to the Brazilian eye, but decisive for the rainfall regime of the Amazon, for agriculture in the Northeast, and for Europe’s climate stability.
-
Uma pessoa reagiu a isso.