But maybe we could beat the plants in efficiency per square meter. There's nothing saying we couldn't improve on density of matter that photosynthesizes, by e.g. packing the plant matter more tightly in artificial conditions. Nature tries to produce organisms that survive and reproduce. We now have a different set of constraints: we need something that can pull out carbon as efficiently as possible. If it can't self-reproduce, we can reproduce it in labs or factories. I feel (hope) there's plausible biology and engineering work to be done here.
- Stop destroying forests (such as Amazon) which are a huge carbon sink for cows which are a carbon source.
- Build more buildings out of wood (wood buildings are carbon sinks) instead of concrete (carbon source)
- All building lumber should be self-sustaining (i.e. replant trees you used to build)
- Stop over fishing and allow oceans to grow unchecked (all living things sequester carbon while they are alive... the ocean is potentially the biggest carbon sink of all and could have several magnitudes more fish and plankton life sequestering billions of tons of carbon)
- Supplement all of the above with man-made carbon sequestration tech
