Study Reaches Extremely Worrying Findings
A new study suggests the Gulf Stream could collapse as early as 2025. The collapse of a warm sea current in the Atlantic threatens to have catastrophic consequences for the climate, but scientists disagree on the new analysis.
The Gulf Stream system may collapse as early as 2025 – This is the conclusion of a new study, writes The Guardian. The cessation of vital ocean currents, called the Atlantic Meridional Overturning Circulation (AMOC) by scientists, would have catastrophic consequences for the climate.
AMOC was already known to be at its weakest level in 1,600 years due to global warming, and researchers have noticed warning signs of a tipping point in 2021, notes The Guardian.
A new analysis estimates the time frame for the collapse between 2025 and 2095, with a central estimate in 2050 if global carbon emissions are not reduced. Evidence of past landslides indicates a temperature change of 10°C over several decades, although this occurred during ice ages.
Other scientists have said that the assumptions about how the tipping point will develop and the uncertainties in the input data are too large to reliably estimate the timing of the tipping point. But everyone acknowledges that the prospect of AMOC's collapse is extremely worrisome and should stimulate rapid reductions in carbon emissions.
The Atlantic meridional overturning circulation carries warm ocean water north to the pole, where it cools and sinks, driving the Atlantic currents. But the influx of fresh water from the accelerating melting of the Greenland ice cap and other sources is increasingly suppressing the currents.
The collapse of the Gulf Stream will have catastrophic consequences around the world, severely disrupting the rains on which the food of billions of people in India, South America and West Africa depend. It will increase storms and lower temperatures in Europe, as well as lead to sea level rise on the east coast of North America. It would also endanger the Amazon rainforest and the Antarctic ice sheets even more.
«I think we should be very worried,» said Professor Peter Ditlevsen of the University of Copenhagen in Denmark, who led the new study. – That would be a very, very big change. AMOC has not been switched off for 12,000 years.
AMOC collapsed and restarted repeatedly in a cycle of ice ages that occurred from 115,000 to 12,000 years ago. This is one of the climate tipping points that scientists are most worried about as global temperatures continue to rise, writes The Guardian.
Studies conducted in 2022 showed that five dangerous tipping points may have already passed from -for global warming of 1.1°C to date, including the shutdown of AMOC, the collapse of the Greenland ice cap, and the dramatic melting of carbon-rich permafrost.
A new study, published in the journal Nature Communications, used sea surface temperature data dating back to 1870 as a measure of the change in strength of AMOC currents over time.
Then, according to The Guardian, the researchers compared this data with the trajectory observed in systems that approach a certain type of inflection point, called the «saddle node bifurcation.» According to Ditlevsen, the data matched «surprisingly well.» The researchers were then able to extrapolate from the findings to estimate when the tipping point was likely to occur. Further statistical analysis made it possible to assess the degree of uncertainty in the estimate.
The analysis is based on the growth in greenhouse gas emissions, as it has been to date. If emissions do start to decline, as envisaged by current climate policy, then the world will have more time to try to keep global temperatures below the AMOC critical point.
The most recent assessment by the Intergovernmental Panel on Climate Change has shown that AMOC will not collapse this century. But Professor Ditlevsen said the models used are of coarse resolution and not suitable for analyzing the non-linear processes involved, which could make them overly conservative.
The potential collapse of the AMOC has been intensely debated by scientists who have previously said it should be avoided » ;at any cost».
Professor Niklas Boer of the Potsdam Institute for Climate Impact Research in Germany has identified early signs of a collapse in AMOC in 2021. “The results of the new study sound troubling, but when one considers the uncertainties in the highly simplified [tipping point] model and the underlying [sea temperature] data, it is clear that these uncertainties are too large to make any reliable estimate. fracture time».
Professor David Thornalley of University College London agreed that there were big caveats and unknowns in the study and said more research is needed: «But if the statistics are reliable and can adequately describe how the real AMOC behaves, then it's very worrying.» result.»
Dr. Lewke Caesar of the University of Bremen, Germany, notes that the use of sea surface temperature as a proxy for the strength of the AMOC currents was a key source of uncertainty: «We only have direct AMOC observations from 2004».
According to Professor Tim Lenton of the University of Exeter, the extrapolation in the new analysis was reasonable. He said that the tipping point could lead to a partial collapse of the AMOC, for example, only in the Labrador Sea, but it would still cause serious consequences. Dietlevsen said he hoped the discussion would spark new research: «It's always fruitful when you don't quite agree.» , where the AMOC tipping point is, but a new study adds to the evidence that it's much closer than we thought. One study provides limited evidence, but when multiple approaches lead to similar conclusions, it should be taken very seriously, especially when we're talking about a risk that we really want to rule out with 99.9% certainty. Now we cannot even rule out that we will pass the tipping point in the next decade or two.