Land Use, Land-Use Change and Forestry

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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).

Time Scale
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 requirements.

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.

Associated Impacts
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 natural forests.

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