Exp

Newman et al., 2001 Volderet al., 2004

this share is expected to increase to 44% by 2020 (FAO, 2000). This section focuses on commercial forestry, including regional, national and global timber supply and demand, and associated changes in land-use, accessibility for harvesting and overall economic impacts. The ecosystem services of forests are reviewed in Chapter 4, while interactions with climate are discussed in IPCC (2007b). Key regional impacts are further detailed in Chapter 10, Section 10.4.4; Chapter 11, Section 11.4.4; Chapter 12, Section 12.4.4; Chapter 13, Section 13.4.1; and Chapter 14, Section 14.4.4. Finally, bioenergy is discussed in IPCC (2007c).

5.4.5.1 New findings since TAR

Confirmation of TAR: Modelling studies predict increased global timber production.

Simulations with yield models show that climate change can increase global timber production through location changes of forests and higher growth rates, especially when positive effects of elevated CO2 concentration are taken into consideration (Irland et al., 2001; Sohngen et al., 2001; Alig et al., 2002; Solberg et al., 2003; Sohngen and Sedjo, 2005). For example, Sohngen et al. (2001) and Sohngen and Sedjo (2005) projected a moderate increase of timber yield due to both rising NPP and a poleward shift of the most productive species due to climate change.

Changing timber supply will affect the market and could impact supply for other uses, e.g., for biomass energy. Global economic impact assessments predict overall demand for timber production to increase only modestly (see Section 5.3.2.2) with a moderate increase or decrease of wood prices in the future in the order of up to ±20% (Irland et al., 2001; Sohngen et al., 2001; Nabuurs et al., 2002; Perez-Garcia et al., 2002; Solberg et al., 2003; Sohngen and Sedjo, 2005), with benefits of higher production mainly going to consumers. For the U.S., Alig et al. (2002) computed that the net impact of climate change on the forestry sector may be small. Similarly, Shugart et al. (2003) concluded that the U.S. timber markets have low susceptibility to climate change, because of the large stock of existing forests, technological change in the timber industry and the ability to adapt. These and other simulation studies are summarised in Table 5.4.

New Knowledge: Increased regional variability; change in non-timber forest products.

Although models suggest that global timber productivity will likely increase with climate change, regional production will exhibit large variability, similar to that discussed for crops. Mendelsohn (2003), analysing production in California, projected that, at first (2020s), climate change increases harvests by

Table 5.4. Examples of simulated climate change impacts on forestry.

Reference; location Scenario and GCM Production impact Economic impact

Table 5.4. Examples of simulated climate change impacts on forestry.

Reference; location Scenario and GCM Production impact Economic impact

Sohngen et al., 2001;

UIUC and

• 2045: production up by 29-38%; reductions

• 2045: prices reduced, high-latitude loss,

Sohngen and

Hamburg T-106 for CO2

in N. America, Russia; increases in S.

low-latitudes gain.

Sedjo, 2005.

topping 550 ppm in

America and Oceania.

• 2145: prices increase up to 80% (no climate

Global

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