423Climate Engineering: Impact Reducer or Suffering Inducer?
issues relating to the potential for and possible approaches to reducing the
concentrations of radiatively active gases and aerosols other than CO
2
.
12.3.1 Expanding the Terrestrial Biosphere
The aboveground terrestrial biosphere (so trees, grasses, etc.) totals ~500 GtC
(Prentice 2001). Expanding or intensifying the extent of forest cover is, thus,
at least conceptually, a way to store additional carbon (Kauppi and Sedjo
2001). However, increasing the uptake of the aboveground biosphere by
1 GtC/year for a century, which would account for only ~10% of present
anthropogenic emissions, would require an expansion of the forest carbon
reservoir by over 15%, which would be a very lar