A broad range of mitigation responses can be conceived. However, the bulk of attention, in both the analytical and policy arenas, has been devoted to reducing the emission of GHGs from anthropogenic sources and to removing the CO2 (the most important GHG) already in the atmosphere by enhancing the biophysical processes that capture it. The timing of these efforts depends partly on the climatic constraints to be observed and on the costs of these actions, which are subject to change over time. Even with an exact knowledge of the timing and consequences of the future impacts of climate change, policymakers will still be faced with difficult choices regarding the implementation of response options. This is because the costs, availability, and associated impacts of future mitigation options are uncertain, and the choices involve trade-offs with important competing environmental and other social objectives. Chapter 8 discusses the costs of different pathways towards a fixed stabilization objective, and notes factors which would favour a larger proportion of preparatory activities relative to mitigation per se as well as factors that favour early mitigation. This section considers the wider context relating to climate change risks and damages.
Inertia and Uncertainty
Various attempts have been made over the past few years to explore these questions.
Arguments that favour a larger fraction of preparatory activities (developing
technologies, building institutions, and the like), rather than emission reductions
in the near-term mitigation portfolio, include losses from the early retirement
of installed capital stock, technological development, the optimal allocation
of resources over time (discounting effect), and the carbon cycle premium (Wigley
et al., 1996). See Chapter 8 for a detailed discussion.
Table 10.7 summarizes the most important arguments brought
forward in favour of modest and stringent emissions reduction in the near term.
Table 10.7: Balancing the near-term mitigation portfolio | ||
Issue | Favouring modest early abatement | Favouring stringent early abatement |
Technology development |
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Capital stock and inertia |
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Social effects and inertia |
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Discounting and intergenerational equity |
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Carbon cycle and radiative change |
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Climate change impacts |
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In addition to those emphasized by Wigley et al. (1996; see above), other arguments are proposed that support less stringent near-term emission reductions as well. Most refer to the significant inertia in economic systems. The first argument below is related to the economic lifetime of already installed capital stock. The second points to the possibility of low-cost mitigation technologies becoming available in the future.
Wigley et al. (1996) refer to the inertia of the capital stock. Researchers also identified other fields of inertia such as technological developments and lifestyles. The essential point of inertia in economic structures and processes is that it incurs costs to deviate from it and these costs rise with the speed of deviation. Such changes are often irreversible. The costs stem from premature retirement of the capital stock, sectoral unemployment, switching cost of existing capital, and rising prices of scarce investment goods. Emissions reduction in the present influences the marginal abatement cost in the future. The inertia of technological development arises from the path dependence. The capital stock can be divided into three parts. First, end-use equipment with a relatively short lifetime can be replaced within a few years. Second, infrastructure, buildings, and production processes can be replaced in up to 50 years. Structures of urban form and urban land-use can only be changed over 100 years. The demand and supply of goods and services in these three domains are interrelated in a complex way (Grubb et al., 1995; Grubb, 1997; Jaccard et al., 1997).
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