Geoscience Reference
In-Depth Information
Geoengineering or technofixes
Geoengineering is the general term used for technologies that could be used to either re-
move GHGs from the atmosphere or to change the climate of the Earth (see
Figure 37
).
Ideas considered under geoengineering range from the very sensible to the completely mad.
At the moment we currently release over 8.5 GtC per year, so any interventions must oper-
ate on a very large scale.
Carbon dioxide removal
. There are three main approaches to the removal and disposal of
atmospheric carbon dioxide: biological, physical, and chemical.
1. Biological approaches on land include the use of biofuels, which were discussed above, and reforestation. Reforestation
or afforestation and avoidance of deforestation are sensible win-win solutions. By maintaining our forest we can retain
biodiversity, stabilize soils and local rainfall, and provide livelihoods for local people via carbon credits. An excellent
example of this in action is in China. By 1990 the Loess Plateau, the bread-basket for the China for at least the last
3,000 years, was turning into a dust bowl. Deforestation and over working of the soils had started to reduce fertility, so
farmers were cutting down more trees to open up more land to produce enough food to survive. The Chinese govern-
ment became aware of this problem and over the next ten years instigated a radical tree-planting programme with
severe punishments for anyone caught chopping down trees. The effects were amazing: the trees stabilized the soils,
greatly reducing soil erosion. The trees through transpiration added moisture to the atmosphere, reducing evaporation
and water loss. Once the trees reached a critical size and area they also started to stabilize the rainfall. The land bio-
sphere is already absorbing about 2 GtC per year of our pollution, and Steve Pacala and Robert Socolow estimate that
if we completely stopped global deforestation and doubled our current rate of planting we could produce another one
of their 1 GtC per year wedges along with all the win-win benefits that go with reforestation. Other estimates by Dr
Yude Pan (US Forestry Service) and colleagues in
Science
suggest this could be much higher if we completely ceased
deforestation and other land use changes (see
Figure 38
)
. In the UK, the Forestry Commission proposed an increase in
the forested land in the UK from 12 per cent to 16 per cent by 2050. This would mean the government's target of 80
per cent reduction in carbon dioxide emissions by 2050 would only be 70 per cent due to the absorption and storage of
carbon by our forests. The one area of the UNFCCC negotiations which are moving forward are the REDD+ discus-
sion (see
Chapter 7
)
whereby tropical developing countries will obtain payments for protecting existing forest which is
under threat or for reforesting areas. REDD+ could make a significant contribution to reducing atmospheric carbon di-
oxide, as well as supporting ecosystem services and providing local and regional environmental security.
