Bravo for igniting a global conversation. The story of the Ditlevsen siblings is well told, and I appreciate your sharing it with us.
It's worth noting that the practice of a 'global mobilization of intellect' was prevalent during the Renaissance. Back then, the world's best minds were focused on understanding the universe, even if it meant dismissing Copernicus and Galileo's observations. Science, at that time, was largely based on consensus.
We view the world in two dimensions, with the Irminger Sea on top. So, we think, water that flows up must also come down by swinging Westerly into the Denmark Straits. The world is spherical, and most of the remnants of the Gulf Stream flow north into the Arctic Ocean to circle the pole in a counterclockwise direction. This warm water melts the Arctic Ocean sea ice, and with the loss of ice, the air over this ocean warms. Come September, there is more open ocean that freezes back into ice. When this happens, the water extrudes salt to freeze. The saltier cold water adjacent to ice is very dense and sinks. This drives the thermohaline circulation of the world’s oceans, with more nutrient-rich water coming out of the Arctic and jets into the Denmark Straits between Iceland and Greenland. Here, cold, nutrient-rich Arctic water collides with warm, nutrient-poor Atlantic Ocean water and dives 11,000 feet down to flow south along Greenland before becoming the Labrador Current.
Talk of the AMOC muddies the waters instead of referring to the currents that make up the AMOC by name, such as the Labrador Current or the Gulf Stream. The AMOC does not have a preferred flow rate of 17 Sverdrups. One must observe each current. The Gulf Stream barrels past Scotland at 140 Sverdrups with a seasonal variation of about 16 Sverdrups.
In 2011, the Gulf Stream surfaced in Svalbard, bringing heat that has commenced melting glaciers and flowing more warm water into the Arctic. Less sea ice follows with more circulation, and more Arctic water enters the Atlantic. The Gulf Stream meanders with wider bends to dissipate more energy.
Here’s to the long life of the AMOC. There will be no critical transition anytime soon. The ocean controls the weather and shapes the climate. It will not be slowed by increasing air temperatures or more freshwater from intensifying rainfall and accelerating ice melt. You can trust the mighty ocean.