Elevator trouble

Simon Donner at Maribo rushed into the elevator and started to show everyone pictures of his kids. Eli noticed another one that Simon had posted on his web site the implications of which will limit your kids and your futures soon. Go read it. Simon thinks that scientists don't know how to communicate danger. Eli thinks Simon and the coral scientists stepped on their lede. Simon noted that

"Scientists, alas, are not great marketers. The plight of the world's coral reefs is a tough sell at a time when most North Americans are "holiday" shopping and powering all manner of coloured lights, inflatable Santas and animatronic reindeer (though the review did garner some front page and radio attention the week of publication).The figure to the right is the first half"

But maybe it is much worse. The figure to the right is the second part of the one at Maribo. As you can when you increase atmospheric CO2 this has the effect of increasing the acidity of the ocean [H+] which in turn decreases the carbonate [CO3 2-] concentration. Carbonate is what sea life builds shells from, and in the end coral reefs. If carbonate decreases that means fewer shells on the beach, no huge deal, no coral reefs, bad, but worse it means that the biological pump could be weakened.

The biological pump is one of the major mechanisms through which excess CO2 in the atmosphere moves into the deep ocean where it is substantially diluted. Without the biological pump, carbon in the three shallow reservoirs, soils and veg, upper ocean and atmosphere pretty much would stay there for a much longer time which means that beyond 480 ppm and a couple of degrees C, we are could be stuck until Milankovitch cycles cool things off enough to drop below the line for forming carbonate shells.

Now this is an exaggeration, because if you go to Maribo and look at the other half of the figure, you will see that even at high CO2 concentrations, if the ocean temperature is low enough (think high latitudes), then carbonate shells can still form, and much of the biological pump is due to phytoplanckton at high latitudes and there are many other issues, but what is true for coral reefs must to some degree should also at some level be true for the biological pump

UPDATE: In the comments Hank Roberts points to work indicating that the biological pump may indeed be slowed down in northern waters such as the Bering Sea.

The scientists found that greenhouse conditions favored smaller types of phytoplankton over diatoms. Such a shift would ripple up the food chain: as diatoms become scarce, animals that eat diatoms would become scarce, and so forth.

“The food chain seems to be changing in a way that is not supporting these top predators, of which, of course, we’re the biggest,” Hutchins said.

A shift away from diatoms towards smaller phytoplankton could also undermine a key climate regulator called the “biological pump.”

When diatoms die, their heavier carbon-based remains sink to the seafloor. This creates a “pump” whereby diatoms transport carbon from the atmosphere into deep-sea storage, where it remains for at least 1,000 years.

While they discovered that increasing CO2 significantly increased the amount of photosynthesis in the smallest phytoplankton, this made little difference as the larger diatoms that feed off the nanoplankton formed much more slowly cutting the food chain and slowing the biological pump.