We all agree that the wind-driven surface flow of the Atlantic Multidecadal Overturning Circulation (AMOC) brings precious warmth from the tropics towards the Arctic & enables a milder climate in Europe and North America. We all agree it’s the oceans that tremendously effect climate and create temperature changes that cannot be explained by a CO2 greenhouse effect.
The AMOC is unique because 1) it carries tropical heat from the south Atlantic, across the equator into the north Atlantic and Arctic Ocean (red currents, graphic A). 2) it creates a reservoir of warm Atlantic water at 100 to 900 meters depth in the Arctic Ocean capable of melting all sea ice 4 times over (graphic C). 3) Because the Atlantic is saltier than the Pacific, it becomes dense enough to sink to the ocean floor when it cools, creating the pressure that drives a deep return current back to the Antarctic (blue currents, graphic A).
When the AMOC slows down, it delivers less heat to the Arctic. Now a growing ocean cold spot south of Greenland suggests the AMOC is indeed slowing down again. To protect global warming narratives, climate alarmists like Stefan Rahmstorf and Michel Mann push the idea that global warming is causing the cooling and that rising CO2 will soon cause a catastrophic AMOC collapse that freezes Europe and disrupts global climates. But the variations in the AMOC’s heat transport have been happening for millennia and do not correlate with changing CO2 concentrations.
Most scientists believe varying AMOC heat transport causes the global see-saw effect contributing to the Atlantic Multidecadal Variability (AMV) (graphic B). When the AMOC strengthens it also pirates more warmth from the south Atlantic. The north Atlantic then warms while the south Atlantic cools. During the 1930s & 40s, the north Atlantic warmed and Arctic sea-ice retreated similar to what is observed today. During the 1970s and 80s, the AMV cycled to cooling the north Atlantic and Norwegian glaciers grew prompting several scientists to warn we were headed for a new ice age. In the 1990s as the AMV cycled and the Atlantic warmed again, the new fear was global warming. Blinkered scientists blamed rising CO2 for the AMOC’s effects. Most ignored the fact that Arctic sea-ice was melting mostly where warm Atlantic water entered the Arctic and downplayed the AMOC see-saw effect that was redistributing heat and causing Antarctic sea-ice to simultaneously increase (graphic D).
Nonetheless those changes provided the ammunition for drama queens and eco-loons like Roger Hallam to create the Extinction Rebellion and Just Stop Oil movements. Ignorant politicians offered government grants to grifting alarmist scientists to demonize CO2 and blame fossil fuels for the warming that they soon hyped as a crisis. To manipulate our fears, alarmist scientists like Katharine Hayhoe falsely claimed the world is warming faster than ever before, rising 1.1°C (2°F) since 1850. But such claims dishonestly ignored climate history and the effects of the AMOC.
During the last glacial period CO2 concentrations were around 180-200 parts per million (ppm) and temperatures were approximately 11 degrees Fahrenheit (6 degrees Celsius) cooler than today. Yet associated with the AMOC effects, the Arctic experienced 25 Dansgaard-Oeschger (D-O) events, raising Greenland temperatures by 18 to 27 degrees Fahrenheit (10 to 15 degrees Celsius) in just a few decades (graphic E, red numbers mark each D-O event in most recent half of glacial period). Such rapid warming can only be explained by the sudden ventilation of Atlantic heat transported via the AMOC and stored in the Arctic Ocean.
As is the case today, the warm salty Atlantic water is insulated from the surface ice and the atmosphere by a layer of fresh water that prevents the heat of the warm Atlantic water from rising to the surface. As the glaciers grew the air dried and the flow of fresh river water into the Arctic was reduced, enabling the warm Atlantic water to rise closer to the surface. Coupled with an increased AMOC bringing more heat, Arctic sea-ice melted, and its stored heat was released, rapidly raising air temperatures.
The ebb and flow of the AMOC today similarly, but less dramatically than during D-O events, contributed to Arctic sea-ice melt, which enabled stored heat to be released. The Arctic temperatures then rose 2 to 4 times faster than anywhere else. The current slowing of the AMOC is simply part of a natural oscillating dynamic. Its current slowdown will soon increase Arctic sea-ice and lower temperatures naturally without crazy Net Zero mandates or Gate’s sun blocking. The slowdown doesn’t mean we are all going to die like the eco-loons and alarmist scientists push with their catastrophic story telling. Whether we burn more or less fossil fuels, it will not change the AMOC. And perhaps it will then be realized that life-giving CO2 is not our enemy!
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