That is actually work-in-process. Biological engineers are trying to upgrade C3 plants to C4, improve rubisco efficiency, and other such performance enhancers

That is actually work-in-process. Biological engineers are trying to upgrade C3 plants to C4, improve rubisco efficiency, and other such performance enhancers for photosynthesis. It's not so much driven by climate changes as by potential agricultural profits, though. If it were the former, they'd make an algae 2.0 and drop it in the ocean. But as C3 to C4 modification could make a hotter, drier rice with 20%-50% higher yield, that's worth a whole lot of money. Of course, that work has been underway for decades--even before CRISPR/Cas9--and golden rice got stomped for no good reason, so even if someone made a super-Sitka-pine exclusively for carbon fixation, it could still get blocked by politics.