Ocean geoengineering scheme aces its first field test
science.org
science.org
There has been quite a lot of interest in Ocean Alkalinity Enhancement (OAE) in the last few years.
This is kind of an unfortunate title, as "geoengineering" (while not wrong) has a very negative connotation in non-scientific publications. Presenting OAE as ocean acidification remediation would have been a much nicer way to drive adoption.
As a side note, lime can be very problematic under some conditions (parasitic CaCO3 precipitation can cause a net release of CO2). But ultramafic rock is alkaline and everywhere. It tuns out you need approximately one large mountain dissolved into the ocean to reverse climate change (neutralize ocean acidification and causes the ocean to take up any extra CO2 in the atmosphere). Or you can just remove acidity from the ocean using solar power, and pour it on rocks somewhere.
> a very negative connotation in non-scientific publications.
yes, after decades in higher ed, I too find a very negative connotation in the field of "geoengineering"
If you have any links I'd love to learn more. (And if your climate research group is involved in stuff like this, I'd love to check that out.)
(may be missing a few)
There are a lot of terrestrial enhanced weathering folks too, where the alkalinity eventually washes into the ocean after being spread on land.
https://iopscience.iop.org/article/10.1088/1748-9326/ac002d/...
... Oceans equilibriate with the atmosphere after a few months (they absorbs more co2 in response to pH/carbonate shift), so one has to keep injecting alkalinity to keep a local ecological effect. The CDR effect is persistent, though.
This seems eminently doable and a lot cheaper than just moving every city away from the coast, among other things.
I feel like there’s some fineprint I’m missing.
If we can just mine a mountain worth of lime and dump it in the ocean, that seems simpler and cheaper than trying to move all our coastal cities. Even if we decarbonize at the maximum possible speed, we’ll still have to do that.
2) Large means quite large. I ran a back-of-the-envelope estimate some years ago and found that the Hawaiian island [1] of Kauai could reduce atmospheric CO2 roughly back to pre-industrial levels if it were completely pulverized and weathered away down to the seafloor. That's trillions of tons of rock.
3) The benefits of curbing CO2 are shared globally, but the costs are concentrated locally. It's the same kind of prisoner's dilemma that results in e.g. people still burning billions of tons of coal each year.
I think that accelerated silicate weathering is the best geoengineering option and one that's likely to be deployed at scale later this century, but it's not really going to be easy.
[1] AKA "underwater mountain, with the top poking above water"
* pun intended
Ocean acidification is a local near-surface phenomenon caused by the oceans absorbing the higher levels of CO2 and pulling the carbonate equilibrium to the left, so to speak. CO2(atm) <-> (H2CO3) <-> (HCO3)- <-> (CO3)-2 -> CaCO3 precipitate ?
I don't know a whole lot about this, but it seems you'd have to keep doing this steadily and gradually for > 100 years (maybe 1000 years) at global scale to get that effect? ...and that's assuming no more fossil fuel combustion was taking place?
As a mitigation for coral reefs, oyster beds etc. it seems to have more immediate value.
One would want to avoid downwelling regions that get sucked into deep ocean circulation before reaching equilibrium (e.g. the north atlantic), that alkalinity would take a long time to come back up and be useful.
> "Caldeira’s team wrote that its approach would be “infeasible” as a global solution. That’s because it’s difficult to make alkaline additives without emitting CO2, he says. Heating limestone to make lime, for example, releases so much of the gas that it partially offsets the increased uptake by the ocean. Even if low-emission lime could be made, it would probably be too costly to dump into the ocean."
> Caldeira and colleagues added sodium hydroxide—also known as lye and an ingredient in many soaps and detergents—to a part of Australia’s Great Barrier Reef. They found it raised pH levels nearly to preindustrial levels, allowing the natural calcification of the reef to increase.
Even that is a rather optimistic take... My Chemistry knowledge suggests it more than offsets what is taken up by the ocean...
As mentioned, this is still quite costly, but it's likely a hurdle we will need to cross regardless to get to green cement.
This results in large zones of anoxic bottom water, or at least hypoxic, aka 'dead zones' as in the Gulf of Mexico. These zones were much more widespread 100 million years ago when many oil and gas-bearing sediments were being laid down, but turning much of our modern ocean into a sulfurous stinking anoxic zone is not the brightest idea.
This can be used as complimentary fertilizer on agricultural land.
When you don't know exactly how things will be affected, then you shouldn't make changes.
This action was the second case and it was only done for monetary concerns. This wasn't motivated by environmental concerns, it was motivated by profit. And the profit motive is exactly what got this planet in to its climate situation.
That’s an impossible standard to uphold. I don’t disagree with your overall premise, but the world is simply too complex to understand all of the ramifications of anything meaningful.
Are you just being snarky and anti-establishment or do you have a concrete criticism to make? Please make it if you do.
...but trying to reverse some of this is bad now?
From reading the article, it seems hard to say the experiment sounded negative?
I think the commenter’s admonition may have been expressing the the same lesson: its hubristic to “fix” systems with hacks like this; whereas carbon drawdown is not a hack, because it operates within the mechanism of imbalance itself.
For my part, this article had so little reporting of the complexity of ocean ecosystems and the potential dangers, not to mention how it buried the bit about how carbon intensive lye is (the same reason that makes concrete have such a huge carbon footprint) that it read like a puff piece.
click
"Yep."
Never change HN.
We can hold to your standard the moment we hold to that standard for other activities, such as burning fossil fuels in the first place.