A pair of companies in Arizona are about to build a system to
pull CO2 out of the atmosphere, attempting to prove that the
"wind-scrubber" concept works. The scrubber will employ sodium
hydroxide, which reacts with carbon dioxide, to remove CO2 from
air drawn through the system. In principle, such systems could
help to reduce carbon dioxide levels already in the atmosphere,
thereby complementing attempts to reduce the amount of
additional carbon being emitted. There are a few problems with
the system under consideration: it may not work; sodium
hydroxide is caustic and toxic; and, according to the article,
"the stored CO2 could be supplied to the oil industry for use in
the process of enhanced oil recovery" -- which seems rather
self-defeating, in the long-run. All that said, the notion of
figuring out ways to actively reduce existing carbon levels
alongside reducing the amount of new carbon added to the
atmosphere is a good idea. If, as some recent reports suggest,
we may be already too late to prevent massi