1. Take carbon out of the ground, where it is not active in any carbon system. Put it in the air, and ultimately the ocean. This releases more carbon into the whole system, and causes problems we all know about. It eventually goes to the water as the parent mentioned, with the acidification problem (s)he brought up. Adding ever more carbon to the system only adds to the total carbon load.

2. Take carbon out of the water, reduce acidification, albeit by transferring it to the air. This doesn't actually put new carbon in the system tho, so it has benefit.

However, the carbon put in the air with #2 is the same as traditional jet fuels from sources in the ground, so those effects cancel out as a consideration in our choice range.

Sure in a perfect world, we would find a way to start actively reducing the amount of carbon in circulation, however, to get there we have to find ways to stop adding new carbon to the system. This helps with that.

[1] I know there are lots of options we could consider, but I highly doubt any option that effectively translates to "have the military be less effective" will fly politically, so I am assuming that short-term achievable options have to have no negative effect from the military POV at minimum.