Professor Stephen Schneider, a climate scientist at Stanford University who in the past has resisted geo-engineering has suggested that humanity is being placed in a precarious position of having to choose between "potentially dangerous, uncontrolled climate change or untested fixes involving large-scale geo-engineering projects."
It
is not clear which of these technologies might work, still less what
social and environmental impacts they may have, or if it is prudent
to adopt any of them. The key is to remember that geo-engineering
involves huge risks and that it is not a get-out-of-jail-free card
for the political establishment.
High Reflection
It may be possible
to inject sulphates into the stratosphere from aircrafts to reflect
the sunlight and cool the earth. However, this does not deal with
ocean acidification caused by rising CO2 and might even cause acid
rain.
Low Reflection
It is possible to pump water vapour into
the air to stimulate cloud formations over the sea, thus raising the
earth's albedo. This approach does not deal with ocean acidification
caused by rising CO2 in the atmosphere.
Fertilising the sea
The
limiting factor for growing phytoplankton - tiny marine plants - is
the lack of iron salts. Adding iron to areas of the sea leads to blooms
which absorb CO2. But weather the plants will sink, taking the carbon
out of circulation, or be eaten, returning the absorbed CO2 to the
atmosphere is not clear.
Mixing Layers
A British idea is to build
giant tubes to carry surface waster rich in dissolved CO2 to lower
depths where it will be locked away under the temperature gradient
that keeps deep water layers from surfacing. Critics fear it could
instead bring carbon locked in the deep ocean to the surface.
