Impacts of unmitigated emissions [a]

Impacts of stabilisation of CO2 concentrations [b]

Impacts of SRES emissions scenarios [c]

Emissions scenarios

IS92a (1 % per increase in CO2-equivalent concentrations per year from 1990)

Stabilisation at 750 and 550 ppm

Four SRES emissions scenarios: A1FI, A2, B1,and B2

Climate scenarios


Derived from four ensemble HadCM2 simulations and one HadCM3 simulation forced with IS92a emissions scenarios

Derived from HadCM2 experiments assuming stabilisation at 550 and 750 ppm; comparison with IS92a

Derived from HadCM3 ensemble experiments (number of runs in brackets): A1 FI (1), A2 (3), B1 (1), and B2 (2)

Socio-economic scenarios

IS92a-consistent GDPa and population projections

IS92a-consistent GDPa and population projections

SRES-based socio-economic projections

a GDP = Gross Domestic Product.

a GDP = Gross Domestic Product.

2.4.65 Land-use scenarios

Many CCIAV studies need to account for future changes in land use and land cover. This is especially important for regional studies of agriculture and water resources (Barlage et al., 2002; Klöcking et al., 2003), forestry (Bhadwal and Singh, 2002), and ecosystems (Bennett et al., 2003; Dirnbock et al., 2003; Zebisch et al., 2004; Cumming et al., 2005), but also has a large influence on regional patterns of demography and economic activity (Geurs and van Eck, 2003) and associated problems of environmental degradation (Yang et al., 2003) and pollution (Bathurst et al., 2005). Land-use and land-cover change scenarios have also been used to analyse feedbacks to the climate system (DeFries et al., 2002; Leemans et al., 2002; Maynard and Royer, 2004) and sources and sinks of GHGs (Fearnside, 2000; El-Fadel et al., 2002; Sands and Leimbach, 2003).

The TAR concluded that the use of Integrated Assessment Models (IAMs) was the most appropriate method for developing land-use change scenarios, and they continue to be the only available tool for global-scale studies. Since the TAR, however, a number of new models have emerged that provide fresh insights into regional land-use change. These regional models

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