188.8.131.52 Technology scenarios
The importance of technology has been highlighted specifically for land-use change (Ewert et al., 2005; Rounsevell et al., 2005, 2006; Abildtrup et al., 2006) and for ecosystem service changes, such as agricultural production, water management, or climate regulation (Easterling et al., 2003; Nelson et al., 2005). Technological change is also a principal driver of GHG emissions. Since the TAR, scenarios addressing different technology pathways for climate change mitigation and adaptation have increased in number (see Nakićenović et al., 2007). Technological change can be treated as an exogenous factor to the economic system or be endogenously driven through economic and political incentives. Recent modelling exercises have represented theories on technical and institutional innovation, such as the ‘Induced Innovation Theory’, in scenario development (Grübler et al., 1999; Grubb et al., 2002), although more work is needed to refine these methods.
For integrated global scenario exercises, the rate and magnitude of technological development is often based on expert judgements and mental models. Storyline assumptions are then used to modify the input parameters of environmental models (e.g., for ecosystems, land use, or climate) prior to conducting model simulations (e.g., Millennium Ecosystem Assessment, 2005; Ewert et al., 2005). Such an approach is useful in demonstrating the relative sensitivity of different systems to technological change, but the role of technology remains a key uncertainty in characterisations of the future, with some arguing that only simple models should be used in constructing scenarios (Casman et al., 1999). In particular, questions such as about the rates of uptake and diffusion of new technologies deserve greater attention, especially as this affects adaptation to climate change (Easterling et al., 2003). However, only a few studies have tackled technology, suggesting an imbalance in the treatment of environmental change drivers within many CCIAV scenario studies, which future work should seek to redress.