Among the many posts we’ve made about the AMOC, or Atlantic Meridional Overturning Circulation, whose imminent demise with catastrophic climate consequences is predicted in the MSM weekly, one of our favourites concerns the Florida current, which runs between the Florida mainland and the Bahamas and which serves as one of the main inputs into the Gulf Stream. Its flow rate is cleverly measured by tracking minuscule magnetic fluctuations in a telecommunication cable running along the ocean floor from West Palm Beach to the Bahamas. For many years scientists thought they detected a downward trend in that rate, leading to all the usual hollering about the impending collapse of the Gulf Stream. But then other scientists cleverly detected a problem with the measurements, namely that the slow migration of the magnetic North pole was inducing a false trend in the cable data, and once it was corrected the data no longer showed a weakening AMOC. We were reminded of this story when reading a recent survey article in Science magazine by Paul Voosen about the findings from new data collected by a monitoring array near the Arctic, called the Overturning in the Subpolar North Atlantic Program (OSNAP – a good acronym for once), along with other monitoring data from locations in the tropics. Contrary to expectations, the data show no weakening of the AMOC other than fluctuations attributable to weather, not climate change. Oh snap!
By combining the array series, a team led by Ben Moat were able to generate AMOC flow measurements back 20 years to 2005. And the result looks like this:
The drop from 2005 to 2010 was very exciting for the we’re-all-going-to-die crowd. Even though some scientists at the time pointed out that it was caused by air pressure changes not temperatures. And in any case since 2014 there has been variation but no downward trend. (As we have said many times and will again, the more natural fluctuation there is, the longer the reliable time series you need to detect trends or, in technical terms, to separate “signal” from “noise” instead of just causing more noise with your panicky cries.)
It gets worse, because the patterns in certain locations simply don’t line up with what models project. The northern branch of the AMOC, which will supposedly shut down in a warming world causing the Gulf Stream to shut off and send Europe into a new ice age, cooling being the new warming, doesn’t appear to be confined to one location and may even migrate further into the Arctic as needed to maintain the flow. Referring to scientists working with the data Voosen notes:
“Most agree the media-stoked drama of collapse has outpaced the evidence. ‘People may be inclined to be more inflammatory,’ says Eleanor Frajka-Williams, a physical oceanographer at the University of Hamburg who previously led RAPID. But that risks oversimplifying a system that resists easy narratives. ‘There’s a reason we don’t have a unified simple theory for the AMOC,’ she adds. ‘It doesn’t exist.’”
As we often say, climate is complicated, and while alarmism sells, eventually reality gets the last word, as long as there are scientists out there willing to listen to what it has to say.
