THC Shutdown, We All Fall Down
The interaction of warm and cold areas within a single fluid body creates a natural churning movement known as convection. The most notable example of this being major weather events like tornadoes and hurricanes, when the combination of cold and warm fronts press against each other. When cold and warm areas in the ocean interact, a natural current called the thermohaline circulation (THC) is formed, scaling the size of the oceans.
Cold from the poles and heat from the equator stirs our planet’s oceans like a lazy spoon in a cup of coffee. This movement allows aerated waters from the surface to mix with water in the deep ocean, providing the O2 necessary for aquatic aerobic life to exist.
As salinity and temperature in the oceans are disturbed the stability of the THC is threatened. If the THC fails, the oceans enter a phase called a THC Shutdown event. If you’ve seen a sad goldfish desperately puffing at the surface of a bowl with no pump, this is an example of a hypoxic aquatic environment.
The map below outlines persistent marine hypoxic areas (Dead Zones) that currently exist. You’ll note that they are mostly on coastal areas. This phenomenon is due to temperature fluctuations as well as nutrient overloads, such as those from fertilizers.
Not all the world is aerobic. Not everything breathes oxygen. In the places where there is no oxygen, there are sulfate reducing bacteria and archaea that create hydrogen sulfide H2S as their waste product. They stay tucked into areas with no oxygen, like the bottom of the ocean. The oxygen rich surface waters creates a buffer, while the sulfate reducing bacteria maintain an H2S rich environments deeper in the water column.
H2S is currently used in emergency medicine to induce coma for extreme trauma patients. By adding controlled amounts of H2S to a respirator, patients can be rapidly put into a state of reduced metabolism. An H2S induced coma slows mitochondrial function delaying death, allowing more time for life-saving treatment, though extended exposure can cause serious chronic health effects, organ failure and death.
Putting the pieces together.
During a THC Shutdown event, dissolved oxygen throughout the ocean is reduced. As the oxygen reduces, the buffer protecting the rest of the ocean from anaerobic bacteria reduces. As the buffer zone decreases the bubble of anaerobic bacteria is allowed to expand. Slowly they move closer to the surface, until the anaerobic zone meets the atmosphere.
As anaerobic bacterial waste dominates the oceans, marine ecosystem collapse is accelerated as everything that breathed O2 suffocates. In what could be a matter of days oceanic hypoxia is complete, atmospheric H2S rises to toxic levels and potentially all animal life on earth goes to sleep and never gets back up.
A simplistic even fantastic sounding theory, yet the scientific community believes it has played out twice in geological history (Anoxic Event) and is backed up by historical precedent. You can see the evidence for global THC shutdown extinction events in the fossil record, or take a walk along the coastal areas of dead zones and smell the sulfur.