SRM could help prevent that by directly lowering temperature, which means less CO2 released and less ocean acidification. And it buys us time to decarbonize before things all fall apart.
However, as other have pointed out, this might be able to buy us some time to develop negative emissions technology (which is ultimately the only way out). Hopefully we would use that time wisely.
There is a moral threat of "with climate management tools, we don't need to act on carbon reduction." I think that is less dangerous than the threat of "we have no validated climate management tools to deal with rapidly accelerated climate change." Ideally, we would research and develop the science and technology of weather control and climate management now so we don't feel compelled to do anything drastic in the near future. For instance, we know that dumping sulfur in the upper atmosphere can cool the earth for <$10b/year. But we don't want to be in that position. Instead, maybe we mandate that all container ships loft saltwater droplets to support cloud formation.
Also, keep in mind that some approaches might be applied locally to protect certain ecosystems rather than aiming for a global effect. E.g., cloud brightening R&D to cool areas with lots of melting permafrost. We should be spending billions on this r&d.
We need time to transition, it's happening. In 20-30 years, we will have a much cleaner global economy, with no coal and minimal oil. But we don't want to have the permafrost melt in the meantime!
Question, what do we know about the ocean as a carbon sink? Is it's capture rate variable with anthing? Is it easier to capture carbon from the ocean than in the air? Could we try to increase the capture rate into the ocean and then extract rapidly from the same area?
Also yes, ocean acidification is likely to be the bigger immediate problem. People depend heavily on fish protein and other sealife. That plus poor farming yields will be bad.
But can you think of any forms of life on the bottom of the food chain that depend on carbon inputs as part of its own metabolic processes in order to reproduce itself? Because if you want a self-sustaining ocean-based carbon capture solution, that’s where I would look.
e.g, instigate some large bloom of plant matter or algae, and engineer/find the right conditions for the matter to sink to the bottom of the ocean without decomposing.
The second part, if you can find a profit motive to compost the ocean floor and actually do it in a profitable way, then it will get done. Else we’re stuck relying on natural processes.
CO2 is easier to chemically react when dissolved into water, and its mobility is about the same as on air. So the decision is about engineering something that can survive being immersed on the ocean vs. engineering something that can use atmospheric CO2. I believe there's no general answer, we can only answer that question for specific designs.
[0] https://www.whoi.edu/oceanus/feature/fertilizing-the-ocean-w...
Someone else pointed out that we can cause blooms. That's basically what you want, because plankton or algae sequester it. I don't know that we can "hack" that without risking damaging the oceans though. They're pretty good at what they do as is.
It is a gas exchange though, so heat and pressure have an impact. They're not great for marine life though. Surface area does as well, though it'd be hard to meaningfully change the ocean's surface area.
The bigger issue would be containment. The ocean is huge, and a very good CO2 sink. Anything that's going to make a significant dent in the total CO2 absorption of the ocean is going to have to happen over a very large area. Things aren't going to be much better if we sterilize the ocean in the process.