One of the biggest issues we have with CO2 is that it is making our oceans more acidic. Injecting it into the water would be devastating to whatever ocean life is near by.

With vast quantities of electricity we could filter the air of CO2 and find a better way to utilize it. Possibly by making hydro carbons with it. The only thing that seems certain to me is that we need some form of carbon free energy production on a massive scale. I always propose nuclear power as the solution.