There is a real upper limit to CO2 in the atmosphere, I think like 5000 ppm, where people will notice it. It eventually becomes deadly. Assuming plants and the ocean don't absorb the extra CO2, and that's a big if, we could hypothetically hit that in a few thousand years or so if we keep burning hydrocarbons at today's levels. It makes sense to develop a backup energy source. There really isn't any urgency though.
There is a real upper limit to CO2 in the atmosphere, I think like 5000 ppm, where people will notice it. It eventually becomes deadly. Assuming plants and the ocean don't absorb the extra CO2, and that's a big if, we could hypothetically hit that in a few thousand years or so if we keep burning hydrocarbons at today's levels. It makes sense to develop a backup energy source. There really isn't any urgency though.
CO2 has been much higher before and the plant life brought down to today's levels. The system is self-correcting if you don't interfere with it. In a few thousand years we'll be off this rock anyway so I don't see any reason to panic about this at all.