There is a tipping point in there, somewhere, that could be good for some plants, but may be associated with past mass extinctions. The scenario is: CO2 spike triggers massive algae bloom, which carpets the sea floor, destroying ecosystems; then absorbs huge amounts of CO2, and drives Earth into an ice-age. I’m not trying to scare anyone, i would just like to understand these complex, nonlinear feedback mechanisms better.
The “tipping point” rhetoric is pretty much nonsense. There have been wide excursions (many times anything we could possibly cause, even with maximum effort to do so) of temp and CO2 in the last few hundred million years without any positive feedback runaways. This is because the postulated mechanisms are actually “unphysical” (meaning contrary to scientific law) in part, and in part because if such mechanisms existed we wouldn’t be here to worry about them (the ‘anthropic principle’).
The one actual climate danger is the implementation (at ruinous cost, naturally) of some hare-brained geo-forming project which actually works and we discover that you must be VERY careful what you ask for, lest you get it!