Atlantic ocean current unlikely to collapse with climate change – new study

Credit: NASA – GISS

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Can we finally forget about this already much-debunked modelling-based climate scare now? It’s repetition ad nauseam has become tedious over the last few years. Researcher: “Our results imply that, rather than a substantial decline, the AMOC is more likely to experience a limited decline over the 21st century—still some weakening, but less drastic than previous projections suggest.”
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The Atlantic meridional overturning circulation, commonly referred to as the “AMOC,” is a system of ocean currents confined to the Atlantic basin that plays a crucial role in regulating Earth’s climate by transporting heat from the Southern to the Northern Hemisphere, says Caltech @ Eurekalert.

The AMOC also modulates regional weather, from the mild summers in Europe to the monsoon seasons in Africa and India. Climate models have long predicted that global warming will cause the AMOC to weaken, with some projecting substantial weakening amounting to a near-collapse relative to the AMOC’s strength today.

Such a weakening would have far-reaching consequences, including changes in regional sea level rise and major shifts in regional climate, such as colder conditions in northern Europe and drier weather in parts of the Amazon and West Africa.

However, a new study from Caltech finds that although the AMOC will weaken under global warming, it is likely to do so to a much lesser extent than current projections suggest.

The team developed a simplified physical model based on fundamental principles of ocean circulation—specifically, how density differences and the AMOC’s depth are related—that also incorporates real-world measurements of the ocean current’s strength, collected over 20 years through the use of monitoring arrays and other observationally constrained products of the Atlantic basin.

The researchers found that the AMOC will weaken by around 18 to 43 percent at the end of the 21st century. While this does represent some weakening, it does not represent substantial weakening that the more extreme climate model projections [Talkshop comment – we don’t need those] suggest.

This new understanding significantly narrows the range of future AMOC weakening, addressing a long-standing uncertainty in climate science.

The study is described in a paper appearing in the journal Nature Geoscience.
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The study suggests that much of the previous uncertainty and some of the more extreme AMOC weakening projections stemmed from biases in how climate models simulate the ocean’s current state, particularly its density stratification.

“Our results imply that, rather than a substantial decline, the AMOC is more likely to experience a limited decline over the 21st century—still some weakening, but less drastic than previous projections suggest,” [lead researcher] Dave Bonan says.

Full article here.
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Image credit: NASA – GISS