IPCC Fourth Assessment Report: Climate Change 2007
Climate Change 2007: Working Group III: Mitigation of Climate Change

9.1 Introduction

In the context of global change and sustainable development, forest management activities play a key role through mitigation of climate change. However, forests are also affected by climate change and their contribution to mitigation strategies may be influenced by stresses possibly resulting from it. Socio-economically, global forests are important because many citizens depend on the goods, services, and financial values provided by forests. Within this context, mitigation options have to be sought.

The world’s forests have a substantial role in the global carbon cycle. IPCC (2007a) reports the latest estimates for the terrestrial sink for the decade 1993-2003 at 3,300 MtCO2/yr, ignoring emissions from land-use change (Denman et al., 2007, Table 7.1). The most likely estimate of these emissions for 1990s is 5,800 MtCO2/yr, which is partly being sequestered on land as well (IPCC, 2007a).

The IPCC Third Assessment Report (TAR) (Kauppi et al., 2001) concluded that the forest sector has a biophysical mitigation potential of 5,380 MtCO2/yr on average up until 2050, whereas the SR LULUCF (IPCC, 2000a) presented a biophysical mitigation potential on all lands of 11670 MtCO2/yr in 2010 (copied in IPCC, 2001, p. 110).

Forest mitigation options include reducing emissions from deforestation and forest degradation, enhancing the sequestration rate in existing and new forests, providing wood fuels as a substitute for fossil fuels, and providing wood products for more energy-intensive materials. Properly designed and implemented, forestry mitigation options will have substantial co-benefits in terms of employment and income generation opportunities, biodiversity and watershed conservation, provision of timber and fibre, as well as aesthetic and recreational services.

Many barriers have been identified that preclude the full use of this mitigation potential. This chapter examines the reasons for the discrepancy between a large theoretical potential and substantial co-benefits versus the rather low implementation rate.

Developments since TAR

Since the IPCC Third Assessment Report (TAR), new mitigation estimates have become available from local to global scale (Sathaye et al., 2007) as well as major economic reviews and global assessments (Stern, 2006). There is early research into the integration of mitigation and adaptation options and the linkages to sustainable development (MEA, 2005a). There is increased attention to reducing emissions from deforestation as a low cost mitigation option, and with significant positive side-effects (Stern, 2006). There is some evidence that climate change impacts can also constrain the forest potential. There are very few multiple land-use studies that examine a wider set of

forest functions and economic constraints (Brown et al., 2004). Furthermore, the literature shows a large variation of mitigation estimates, partly due to the natural variability in the system, but partly also due to differences in baseline assumptions and data quality. In addition, Parties to the Convention are improving their estimates through the design of National Systems for Greenhouse Gas (GHG) Inventories.

Basic problems remain. Few major forest-based mitigation analyses have been conducted using new primary data. There is still limited insight regarding impacts on soils, lack of integrated views on the many site-specific studies, hardly any integration with climate impact studies, and limited views in relation to social issues and sustainable development. Little new effort was reported on the development of global baseline scenarios of land-use change and their associated carbon balance, against which mitigation options could be examined. There is limited quantitative information on the cost-benefit ratios of mitigation interventions. Finally, there are still knowledge gaps in how forest mitigation activities may alter, for example, surface hydrology and albedo (IPCC, 2007b: Chapter 4).

This chapter: a) provides an updated estimate of the economic mitigation potential through forests; b) examines the reasons for difference between a large theoretical potential and a low rate of implementation; and c) and integrates the estimates of the economic potential with considerations to both adaptation and mitigation in the context of sustainable development.