I believe if it is accepted that a carbon diet strategy is unfeasible (and very expensive), then we can proceed to a scheme that is viable. 

There is a very inexpensive simple way to immediately cool the Earth: just put a small amount of aerosol into the air to dim the sun. We won't be able to stop rapid ecosystem collapse without geoengineering. Soon melting permafrost will overwhelm any cuts we make to our emissions.

"The alternative (to geoengineering) is the acceptance of a massive natural cull of humanity and a return to an Earth that freely regulates itself but in the hot state." --Dr James Lovelock, August 2008