As of April 19, 2026, no “AMOC To Collapse–Part 99” has appeared on Paul Homewood’s blog. The most recent entry remains Part 98 (published April 17, 2026), which discussed the new study in Science Advances by Valentin Portmann et al. (published April 15, 2026).

“Critical Atlantic current significantly more likely to collapse than thought”

This headline, which appeared in April 2026 media coverage, refers directly to the Portmann et al. paper.

The study uses statistical observational constraints (real temperature and salinity data) on CMIP6 climate models.

It concludes that the models projecting the largest future slowdown align best with current observations — especially after correcting a South Atlantic surface salinity bias. This narrows the projected weakening to ~51% ± 8% by 2100 under a mid-range emissions scenario (compared with the raw multi-model mean of ~32%).

Grokipedia describes the Atlantic Meridional Overturning Circulation (AMOC) as the density-driven ocean conveyor that transports roughly 15–20 Sv of water and about 1 petawatt of heat northward. Warm, saline surface waters flow north, cool and sink in the subpolar North Atlantic, then return southward at depth.

The Portmann study is viewed as a legitimate statistical refinement that narrows model uncertainty in one direction. However, Grokipedia stresses that it still depends on the same underlying models, which have known limitations: wide inter-model spread, biases in salinity budgets, deep convection, eddy processes, and the frequent need for unrealistic freshwater hosing experiments to simulate shutdowns.

Grokipedia consistently prioritizes sustained monitoring arrays:

The RAPID-MOCHA array (26.5°N, continuous since 2004) recorded a weakening of roughly 1.0 Sv per decade during the 2000s, with a short-term dip in 2009–2010 linked mainly to wind and North Atlantic Oscillation variability. Since the early 2010s the trend has paused or stabilized. The 2022 annual mean transport was 15.2 Sv (after instrumental corrections), remaining within the range of natural variability. Daily-to-decadal fluctuations of up to 5 Sv are common and largely driven by winds and eddies.

The OSNAP arrays (subpolar North Atlantic, since 2014) show significant interannual variability but no sustained long-term decline beyond natural factors.

Proxy reconstructions indicate that recent changes remain within Holocene historical ranges (typically 2–3 Sv fluctuations around a 16–18 Sv baseline). During much of the Holocene — including warmer periods in Greenland under orbital forcing with lower CO₂ levels — the AMOC showed stability without collapse.

The headline reflects a useful update to model projections.

Direct observations from RAPID and OSNAP, however, do not show acceleration toward collapse. Instead, they indicate natural variability with recent stabilization. Past abrupt weakenings in the paleoclimate record required massive natural freshwater pulses far larger than today’s gradual contributions.

Grokipedia assigns low probability (<10%) to a full AMOC collapse before 2100, with gradual weakening driven by a mix of natural variability and anthropogenic forcing being more consistent with current empirical data.

Continued real-time monitoring through arrays like RAPID remains the most reliable guide.

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AMOC To Collapse–Part 98

From NOT A LOT OF PEOPLE KNOW THAT

By Paul Homewood

h/t Ian Magness

The perennial scare story raises its head one more!

The critical Atlantic current system appears significantly more likely to collapse than previously thought after new research found that climate models predicting the biggest slowdown are the most realistic. Scientists called the new finding “very concerning” as a collapse would have catastrophic consequences for Europe, Africa and the Americas.

The Atlantic meridional overturning circulation (Amoc) is a major part of the global climate system and was already known to be at its weakest for 1,600 years as a result of the climate crisis. Scientists spotted warning signs of a tipping point in 2021 and know that the Amoc has collapsed in the Earth’s past.

Climate scientists use dozens of different computer models to assess the future climate. However, for the complex Amoc system, these produce widely varying results, ranging from some that indicate no further slowdown by 2100 to those suggesting a huge deceleration of about 65%, even when carbon emissions from fossil fuel burning are gradually cut to net zero.

The research combined real-world ocean observations with the models to determine the most reliable, and this hugely reduced the spread of uncertainty. They found an estimated slowdown of 42% to 58% in 2100, a level almost certain to end in collapse.

The Amoc is a major part of the global climate system and brings sun-warmed tropical water to Europe and the Arctic, where it cools and sinks to form a deep return current. A collapse would shift the tropical rainfall belt on which many millions of people rely to grow their food, plunge western Europe into extreme cold winters and summer droughts, and add 50-100cm to already rising sea levels around the Atlantic.

Dr Valentin Portmann, at the Inria Centre de recherche Bordeaux Sud-Ouest in France and who led the new research, said: “We found that the Amoc is going to decline more than expected compared to the average of all climate models. This means we have an Amoc that is closer to a tipping point.

Full story here, if you want a good laugh.

Meanwhile, back on Planet Earth, the Met Office say nothing unusual is happening at all to the AMOC:

But crooked scientists has grant money to earn and far left Guardian hacks have headlines to write. It’s a marriage made in heaven!