If only there were existing storage mechanisms that existed in remote areas like forests or swamps. We could probably protect those areas, maybe even put new storage devices in. Ideally, of course, they'd run off a renewable source of energy like solar and be self-cooling. Of course, we wouldn't want the upfront cost to be prohibitive, so something self-replicating would be great. And to diagnose the health of these systems, maybe something humans have had centuries of experience managing? It'd be even cooler if we could locate a bunch of them dispersed throughout the ocean too.
Plants. The answer is, and always has been, to stop emitting additional carbon from fossil fuels, restoring ecosystems, and letting plants and algae and natural carbon sequestration mechanisms do their thing. It also feels pretty inarguable that making that change would be possible if literally everyone on Earth went "yeah, let's do that."