Is it completely ridiculous to imagine that ocean acidification could be countered? I'm imagining something like having cargo ships sprinkle sodium hydroxide in their wakes. Could any such plan be workable?
The most straight-forward way to counter ocean acidification is to reduce the amount of atmospheric CO2. If the atmospheric concentration shifts, the ocean will release the CO2 it's absorbed and its pH will go up.
Granted, that's a pretty tall order. Ideally, we would reduce the atmospheric CO2 from ~400ppm (where it's out now) to 200ppm (where it was before the whole industrial revolution began). At the very least, we probably want to reverse the current trend of +2.0ppm / year to (say) -2.0ppm / year, so hopefully we skim under whatever the wire is.
Some researches claim that the Little Ice Age was caused by the reforestation of the Americas after Europeans accidentally killed all of the Americans who were keeping the content pretty clear of trees. [1] It is estimated that reforesting the Americas sucked about 6ppm to 10ppm of CO2 out of the atmosphere.
So one way to suck CO2 out of the atmosphere is to grow a lot of trees (or other plant life). And then do that every year for about a century; it's not enough to simply reforest even the entire world once, because that would probably only suck (say) 20ppm of CO2 out of the atmosphere, a mere tenth of the target. So after you grow your primordial forest, you need to chop it all down, bury it (or do anything else with the wood that doesn't release its carbon back into the atmosphere), and then plant a new forest, and keep doing it over and over again for however long it takes to get the atmospheric CO2 levels to where you want them to be.
So it's possible to counter ocean acidification, and maybe not even that hard (hell, you're even creating a bit of a "wood rush", since you're going to have lumber coming out of your ears by the time you've regrown enough trees to cover the world ten times over), but I don't really see it happening.
ETA: Based on the figures for tree productivity [2] it looks like you'd need to add about 90 million square km (5% of the Earth's land area) of forests operating at peak productivity to go from +2ppm to -2ppm atmospheric CO2.
1) The temperature effect doesn't really matter. Trees remove CO2 from the atmosphere which raises the pH of the oceans.
2) You're confusing the end of the Medieval Warm Period with the beginning of the Little Ice Age. The Medieval Warm Period ended in approximately 1250 AD; the Little Ice Age began in approximately 1550 AD. While it is possible that the two events are related, there is no reason to assume they are.
As a result of doing that, you'd be transferring the CO2 from the oceans back into the atmosphere.
I'm still unsure about the appropriate process of dealing with all the CO2 released over the last ~200 years - it originally came from somewhere, I'd imagine likely the atmosphere - then over millions of years it was sequestered into the earth through coal and oil. And we've undone that sequestering in a very rapid manner, over approx 200 years, an instant in geological terms.
I'd say the hammer stroke hasn't even started ringing yet, and we haven't even begun to see the changes that we've unleashed - and who knows what they might be? So many unknown unknowns there... and we're attempting to throw our best minds at it, yet we're also still very much continuing with our current trajectory.
Not really. The core issue is that Co2 creates an acidic environment and lowers pH levels. It would be like trying to clear a room filled with poison gas by blowing bubbles filled with oxygen...
Yes, I understand that. But there's something to be said for tackling the easiest problem first. If a relatively straightforward geoengineering solution is available, I think we should go ahead and apply it, and then turn our attentions to the more politically and economically difficult problems of overfishing and pollution.
There are so many second, third, and fourth order effects to any change that you make of any meaningful scale. Humans just don't understand the reef well enough.
We're already changing the applicable conditions. Not changing them is not an option at this point.
I understand there are always risks to sticking our fingers into something we don't understand well. But those risks have to be weighed against the risks of inaction, which seem in this situation to be quite substantial.
I suggested sodium hydroxide because adding sodium ions to the ocean is obviously benign. Seems to me the greatest risk from doing this is that the concentrated alkalinity will kill marine life before it disperses. I don't know whether that's a show-stopper.
I also haven't penciled out the numbers to see how much NaOH would be required, and how that compares to current world production. I have no idea whether this is practical. But I think we should be asking these kinds of questions.
I actually have some experience with this on a very small scale. To raise the pH of my 30 gallon reef tank, I add a tiny amount of a product that is mostly NaHCO and Na2CO3.
Still, it is complex and scary, and I have had better success by increasing flow and surface agitation for better oxygen exchange. Just like I would prefer to have less CO2 in our atmosphere.
