Slowing Atlantic current a global security threat

Summary

• Greenland's location and resources are vital for US/Europe defence, especially as melting Arctic ice opens new shipping routes, boosting its security and trade importance.
• Greenland's melting ice sheet contributes to sea level rise (7m if fully melted) and disrupts the Atlantic Meridional Overturning Circulation (AMOC).
• AMOC's potential collapse by 2100, labelled a security threat, could cause European cooling, monsoon shifts, and accelerated Antarctic melting.

SINGAPORE – Greenland’s location in the North Atlantic and its mineral riches make it increasingly vital for the defence and security of the US and Europe.

At the same time, warming in the Arctic is melting sea ice and opening northern shipping routes that cut travel times between East Asia and Northern Europe.

This makes Greenland and the Arctic even more important to security and global trade.

But there is another side to the story. A melting Arctic – where temperatures are increasing three to four times the global average – could create risks that become major security threats globally, scientists say.

Greenland’s vast ice sheet is melting quickly, contributing to global sea-level rise.

The influx of freshwater into the North Atlantic is also contributing to a slowdown of a key Atlantic Ocean current that brings warmth to Europe and influences monsoon rains in Asia and elsewhere.

If this ocean current collapses, the consequences will be felt around the globe.

Here is a look at the risks and their implications.

How fast is Greenland melting?

Since the mid-1990s, the ice sheet has been shrinking each year, losing an average of about 140 billion tonnes of ice annually, the Geological Survey of Denmark and Greenland has said.

In 2024, it estimated that Greenland was losing 2.5 million litres of water a second – the equivalent of about three Olympic pools.

The ice sheet holds enough ice to raise sea levels by 7m, threatening the survival of coastal cities around the globe. At the current rate, it will take centuries to melt, but the worry is that increased warming will speed up ice loss.

What is at risk?

The Atlantic Meridional Overturning Circulation (AMOC) is a slow-moving current that shifts huge amounts of warm water from the South Atlantic to the north.

This warmth gives much of Europe its milder climate.

The AMOC is part of a global network of currents that shift heat and nutrients around the world’s oceans, playing a crucial role in regulating the planet’s climate.

Imagine the Atlantic current as a giant conveyor belt: As it moves past northern Europe, the water cools. As cold water is denser than warm water, it sinks and moves southwards past Greenland.

The sinking water helps propel the current and maintain the flow of heat around the planet.

What might happen?

Scientists say the current is at its slowest in more than 1,000 years. The concern is that global warming will continue to slow the current, possibly causing it to collapse by the end of this century.

Warmer Arctic temperatures are already melting sea ice and warming the far North Atlantic – making the water less dense and less prone to sinking. At the same time, meltwater from Greenland is diluting saltier water in the North Atlantic. This also makes the current less prone to sinking to the depths, disrupting its flow.

Further heating of the Arctic and accelerated melting of Greenland’s ice cap mean drastic changes to the current could occur within decades, scientists warn.

A collapse would cause temperatures to fall in Europe, especially in winter, and trigger more stormy weather. It would also shift global monsoon patterns, triggering widespread droughts in regions, including South Asia and Africa.

It could also hasten the melting of the West Antarctic ice sheet, pushing up global sea levels.

What do scientists say?

A 2025 study published in the journal Environmental Research Letters found that the collapse of the current could no longer be considered a low-likelihood event. The more greenhouse gas emissions are produced in the coming years, the higher the chances of a collapse by 2100, the researchers said.

Separate research published in 2024 specifically pointed to meltwater from Greenland and Canadian glaciers as a major risk to the AMOC. The researchers estimated that at 2 deg C of global warming, the current would likely become a third weaker than it was 70 years ago. The world has already warmed 1.3 deg C on average since pre-industrial times.

In 2025, Iceland officially classified the potential collapse of the AMOC as a national security threat, viewing it as an existential risk to the nation’s climate, economy and resilience.

“The destabilisation of AMOC is no longer a distant scenario – it’s a national and global security risk,” said Professor Johan Rockstrom, director of the Potsdam Institute for Climate Impact Research.

“We are entering a phase of climate change where uncertain but catastrophic risks can no longer be ignored,” he said in a statement in February.

Professor Sybren Drijfhout from the University of Southampton, who is lead author of the 2025 study in the Environmental Research Letters, told The Straits Times that the impacts will take time to be felt. “An AMOC shutdown is a slow process that takes about a hundred years to complete.”

If the current does collapse by 2100, the full effects will not be felt until 2200, he said.

For Europe and the North Atlantic, the extent of any cooling will depend on how hot the world becomes.

A global average temperature increase of around 1.5 deg C above pre-industrial levels will lead to net cooling, while a higher global average warming of 4 to 6 deg C will lead to net warming, driving the continued melting of the Greenland ice sheet.

He said the Asian monsoon will weaken, which will be the main impact on Singapore. But the exact impact on rainfall for the Republic remains unclear.

Professor Laurie Menviel from the University of New South Wales, a co-author of the 2024 study, told ST: “An AMOC shutdown might lead to 1 to 2 deg C cooling over South-east Asia, but most likely smaller (than this) over Singapore.

“AMOC weakening under global warming would thus slow down the warming in that region. However, it should also lead to drier conditions.”