Apart from photosynthesis, is there no way of breaking down CO2 into C and
O2?
I don't suppose that using the increased amount of water from rising sea
levels (minus the salt) to irrigate the Sahara and plant an additional
forest there is a viable option.

--
Gianna Stefani

The biggest 'biomass' (and the one we know least about) that takes CO2 out
of the atmosphere is the plankton. Dead plankton sinks to the seabed and is
incorporated into sedimentary carbonate rocks (shales, limestones & chalk
etc.). Not sure how the CO2 uptake per square Km compares to the forested
areas of the globe - but the ocean is indeed a huge surface area and
effectivley a CO2 sponge- locking away CO2 in rock form for milenia. Carbon
in 'forest' form might be re-released as CO2 in a few short months by forest
fires, natural decay etc. What we really need is a 'Super Plankton Bloom' to
suck out all that nasty CO2!! The geological past proof of such activity is
the chalk and limestone layers which are hundreds of feet thick. Coal layers
from past forests (though much compressed) are rarely more than a few tens
of feet thick. It's highly probable that extra CO2 in the atmosphere may
largely be absorbed by the oceans.

Nevillef