Fact Sheet 4.20. Sequestration/Displacement Tradeoff
This Fact Sheet illustrates the sequestration/displacement tradeoff discussed
in Section 4.5.2.
Use and Potential
Most of the projects under the Activities Implemented Jointly (AIJ) phase have
involved sequestration rather than displacement. This situation reflects the
reality that the pattern of response is influenced by the time horizon: Displacement
of fossil fuel emerges as more effective only in the long run (Marland and Schlamadinger,
1997). Projects such as these provide a future opportunity for biofuel and forest
products in the long term. This future potential does not mean that different
(additional) land is needed later. The tradeoff is not a once-for-all choice
but a dynamic process; the pattern will shift from initial long-rotation sequestration
to eventual short rotation-based displacement of fossil fuel (Figure
4-15). In Figure 4-15, Read (1999) has modeled
a 70-year projection of the impact on GHG levels, relative to two reference
scenarios-business-as-usual (IPCC, 1992) and fossil-free (Greenpeace, 1993)-on
two patterns of land-use changes: enhanced biofuel alone and "buffer stock"
sequestration plus enhanced biofuel. The latter leads, by about 2040, to ~4
Gt C annual absorption and a cumulative reduction of ~40 ppm CO2 in the atmosphere.
This effort implies an ambitious program of sustainable development pursued
consistently over several decades and involving a large number of community-scaled
plantations (Read, 1999). It has only a modest effect in 2008-2012.
Figure 4-15: CO2 mitigation with dynamic land-use
policy (FLAMES model). Impact on GHG levels over 70 years comparing
two reference scenarios [business-as-usual (BAU) and fossil-free energy
scenario (FFES)] with two land-use scenarios (enhanced biofuel and enhanced
biofuel plus "buffer stock") (Read, 1999).
Biomass growth absorbs CO2 that is returned to atmosphere after felling-either
immediately when it is used as biofuel or more slowly when it is used in conventional
forest products, from paper to timber. Long-term removals from atmospheric CO2
result from substitution in the commercial energy and forest product system,
with fossil fuel left underground or biodiverse natural forests-which might
otherwise be lost-left standing.
Current Knowledge and Scientific Uncertainties
Modeling of land-use change dynamics is in its infancy and has so far been performed
only in global (one region) simulations. Multi-region simulations are expected
to show improved outcomes when the buffer stock is focused on industrialized
regions, where sunk costs in energy sector infrastructure investments are very
large (and where populations are largely urbanized, with surplus agricultural
land and only minor rural unemployment).
The tradeoff involves a several decade dynamic process of land-use change that
lasts several decades.
Monitoring, Verifiability, and Transparency
Because monitoring processes are required under the CDM, verification in developing
countries would be covered by arrangements for project-related carbon credits.
Verification of these essentially commercial activities in industrialized countries
would also be covered by commercial accounting procedures, subject to disclosure
Although sequestration is of limited duration, the related CO2 mitigation is
not necessarily impermanent because carbon credit creation is a commercial activity
that will not leave mature timber from the sequestration phase to rot on felling.
It will be used either in lieu of timber from biodiverse natural forest or as
biofuel or in lieu of fossil fuel-intensive materials. Thus, permanence resides
in fossil fuel left underground or natural forest left undisturbed.
Investing in "buffer stock" forestry is a low-cost, low-risk option, precautionary
against climate science finding a low threshold GHG level for a dangerous "rapid
non-linear climate change event" (Houghton, 1998). Carbon stored in new forest
provides greater flexibility, enabling possible responses to bad news from lower
CO2 levels and providing raw material for a rapid shift to "back-stop" biofuel
technology, if needed. If no threshold is revealed, the new forests can be left
to grow to maturity to meet demands for timber, avoiding depletion of biodiverse