A major ocean current could be shut down by 2050 due to the surge in global warming over the last 15 years, according to new research by an international team of climate scientists.

The potential shutdown of a critical ocean current due to the rapid melting of polar ice by 2050 poses significant risks, including severe sea level rise along the U.S. East Coast and disruptive climate changes in northwestern Europe.

The new study,“Global Warming Has Accelerated: Are the United Nations and the Public Well-Informed?”, highlights the potential shutdown of a critical ocean current by 2050. The Atlantic Meridional Overturning Current (AMOC), influenced by the rapid melting of polar ice, poses significant risks to slow or shutdown, including severe sea level rise along the U.S. East Coast and disruptive climate changes in northwestern Europe.

The study’s authors stated that the rate of global warming since 2010 has risen by more than 50% compared to the rate of warming in the previous forty years, rising by more than 0.7 degrees Fahrenheit (0.4 degrees Celsius) in the last two years alone.

According to James Hansen, a former NASA climate scientist who led the team and whose 1988 testimony to Congress was one of the first public warnings about the risks of greenhouse gas emissions, the Paris Agreement goal of keeping global warming to between 2.7 and 3.6 degrees Fahrenheit (1.5-2 degrees Celsius) is essentially dead at the current rate.

What follows?

The rate of warming will accelerate the spread of deadly diseases linked to warmer temperatures, exacerbate drought and flooding extremes, and intensify already deadly heatwaves.

According to a 2024 study, the closure of the Atlantic Meridional Overturning Current (AMOC), which is the subject of the new paper, would cause a sharp increase in sea level along the East Coast and bring climate extremes that could threaten crops in Europe.

Because parts of the tropical Pacific Ocean are experiencing La Niña conditions, which are a cool phase of a cycle that can lower the annual global average temperature by up to 0.36 degrees Fahrenheit, scientists predicted that the global average temperature would begin to decline this winter.

Warmest January on Record

With the warmest January on record—3.13 degrees Fahrenheit (1.74 degrees Celsius) above the pre-industrial baseline—temperatures instead continued to rise into 2025. Scientists have observed that the prolonged warmth is surprising.

The new findings, confirm that the decrease in sulfate aerosol pollution over the oceans of the Northern Hemisphere is a major cause of the warming, Hansen said. This shift, brought about by more stringent shipping fuel laws, has the effect of reducing cloud reflectivity and increasing the amount of heat that reaches the Earth’s surface.

Other studies examining the astounding 0.7-degree Fahrenheit increase over the last two years concluded that, in addition to aerosol reductions, a Pacific Ocean warm phase and decadal shifts of large-scale pressure patterns could be responsible for the spike.

AMOC Shutdown?

The Arctic is experiencing the most severe effects of global warming, which is melting far more ice and releasing more freshwater into the North Atlantic than most climate models currently predict. There could be disastrous effects from that water inflow, especially for the Atlantic Meridional Overturning Circulation (AMOC) ocean current that warms a large portion of Western Europe, especially the United Kingdom.

According to the researchers, “unless steps are taken to reduce global warming, a shutdown of the AMOC is likely within the next 20-30 years.” They added that their caution regarding AMOC runs counter to the findings of the Intergovernmental Panel on Climate Change (IPCC).

Though its most recent global assessment, conducted in 2021, concluded that the AMOC will slow in a warming climate, the IPCC, the United Nations body tasked with evaluating climate science and investigating policy options, did not find it likely that the current would shut down this century.

Hansen noted,”the ocean conveyor that carries a huge amount of heat into the Northern Hemisphere, if it shuts down, the heat stays in the Southern Hemisphere and will lock in many meters of sea level rise.”

“We can adapt to more extreme heat waves, droughts, storms and floods, and minimize their impact, but the main issue is the sleeping giant, the point of no return, the danger of an AMOC shutdown and large sea level rise.”

Hansen said that by concluding that an AMOC shutdown is unlikely this century, the IPCC failed to sufficiently warn the public about this “point of no return.” He pointed out that a 2015 paper that included an AMOC shutdown warning was rejected by the panel because it demonstrated an excessive amount of freshwater entering the Atlantic from melted Arctic ice.

“But now, surely, ice melt will accelerate, warmer Pacific water is beginning to flow over the Aleutian shelf into the Arctic Ocean surface layer. And in the North Atlantic, warmer water is invading under the sea ice and under Greenland ice shelves.”

“Earth history demonstrates that such ocean warming can result in rapid sea ice loss at both poles, and during periods of rapid warming, sea level can rise several meters within a century.”

“We must understand this situation better, models used by the IPCC are not realistic.”

Bob Kopp, a climate and sea level researcher at Rutgers University, posted Tuesday on Bluesky that Hansen is “just flat wrong” to make sea level rise projections based on the assumption that we’re already in an era of exponentially rising polar ice loss. The most current calculations of ice mass loss don’t support those projections, he said.

And climate scientist Michael Mann, director of the Center for Science, Sustainability & the Media at the University of Pennsylvania, responded to previous research by Hansen about the reduction of aerosol pollution accelerating warming of the oceans by noting that the recent two-year global temperature increase is within the range of warming projected by models.

A fundamental problem

The research was discussed in a webinar hosted by Jeffrey Sachs, president of the Sustainable Development Solutions Network of the United Nations. He pointed out that Hansen has been more consistently accurate than any other in his long-term climate projections.

“Jim, you’ve scared the wits out of me for 25 years as your colleague, because you’ve told me consistently, ‘It’s worse than we think, and it’s accelerating more rapidly,’” he said during the discussion. “You warned us what was coming. This new paper is dramatic. Its implications are global. It must be heard by everybody.”

According to Sachs, the world is facing political issues in addition to the climate crisis, “with leaders in the United States and other countries for whom ‘drill, baby drill’ is the predominant ethos and policy.”

“It’s an absolutely immoral reality we’re facing … an utter political disaster of the whole Earth being in the hands of a few greedy interests, they happen to buy politics. They happen to buy leaders, they happen to own states.”

The world is not governed by even the most basic ethical standards of survival, decency, and respect for young people and for future generations, he continued, adding that different approaches to combating global warming, such as carbon taxes or geoengineering, “don’t solve the fundamental problem.”

Blasting through 1.5C

The importance of examining the science in the context of politics was also underlined by Kevin Anderson, a professor of energy and climate change at the University of Manchester in the United Kingdom who was not involved in the new paper.

“Otherwise it’s just an interesting academic discussion,” he said.

“Whether we align with the more conservative forecasts of the IPCC or the more challenging warnings of Jim Hansen, the policy implications are strikingly similar,” he said. “We are rapidly blasting through the 1.5-degree Celsius commitment.”

Starting now, he said, global emissions must be reduced by 7% annually, which would be an even greater decrease than that which happened during COVID lockdowns, in order to meet the IPCC’s goal of staying well below 2 degrees Celsius of warming.

“In this context, the policy process has abdicated its responsibilities, opting instead for short-term acquiescence with business as usual, rather than offering strong, transparent and cogent leadership,” Anderson said. “After decades of half-truths, delusion and outright lies from those in positions of power, and often from their advisers as well, we now find ourselves facing severe risks of disastrous outcomes.”

“And a lot of climate damage has already been done, primarily to those who weren’t responsible.”

“We are not sleepwalking into the apocalypse, we’re charging toward it with full awareness of what’s at stake, even more damning, we can already see the devastating effects of our actions tearing apart the livelihoods, and even the lives, of vulnerable, often poor, low-emitting communities far from the high-emitting areas where we live, and frequently comprised of people of color.”

Not Just Aerosols

According to Kevin Trenberth, a distinguished scholar with the National Center for Atmospheric Research and an honorary academic with the University of Auckland’s physics department in New Zealand, the new study may have found that the decrease of aerosols and related cloud changes was a significant factor in the recent warming spike in the Northern Hemisphere, but the Southern Hemisphere has also warmed, so aerosols are not likely to be to blame.

“Hansen has never not been political and has his own, often unproven views,” Trenberth said. “Changes in the Northern Hemisphere may well be enhanced by fewer pollutants … but the biggest changes are in the Southern Hemisphere and guaranteed not from that cause.”

He noted new research is in the works focusing on big changes in atmospheric circulation and ocean currents.

“My impression is that the ocean has warmed to a point where it matters,” he said. “The ocean stores most of the excess heat from global warming.”

Although he agrees with recent assessments that the recent warming falls within the range of modeled projections, scientists are still unsure of exactly what happened between 2023 and January 2025.

Jonathan Overpeck, a climate scientist and environmental education professor at the University of Michigan’s School for Environment and Sustainability, stated that he does not find the acceleration of warming surprising.

“There are many amplifying positive feedbacks in the climate system that could come into play, and there have been changes in forcing that likely increased the rate of the climate change as well,” he said, adding that air pollution from ships acted “against the warming to a small degree.”

He said that although there is uncertainty in how global temperatures are measured, the significant increase in record-warm global temperatures in 2023 and an even warmer year in 2024 clearly indicates that the rate of climate change is accelerating.

“If we don’t start phasing out the use of fossil fuels, climate change, and not just the warming, will get much more costly,” he said. “Weather and climate disasters of the type we’re already seeing more of will continue to get a lot worse.”

See also

This article is based on Bob Berwyn’s article published at InsideClimateNews.

Related

• Global Warming will now Accelerate (2023)
• Ice Melt, Sea Level Rise and Superstorms (2016)