ABSTRACT
The Intergovernmental Panel on Climate Change (IPCC 2007) Fourth Assessment Report states that greenhouse gas (GHG) emissions should be reduced to 50–80 per cent of 2000 levels by 2050 to increase the likelihood of stabilizing atmospheric carbon dioxide (CO2) concentrations. Current knowledge, however, points out that any GHG emissions corresponding to a specified maximum warming or reasonable concentration target (e.g. 450 ppm) by a specific date are poorly known owing to uncertainties in the carbon cycle and the climate response (Meinshausen et al. 2009). What is known is that achieving any meaningful GHG reduction by 2050, as recommended by the IPCC, will necessitate a fundamental shift and evolution in the energy system and that tipping points in the earth system are possible (Lenton et al. 2008). The International Energy Agency (IEA) and the US National Research Council’s (NRC) America’s Energy Futures report scenarios have shown that a rapid transition within the global energy system is both necessary and achievable, even if every passing year of inaction increases the cost and reduces the feasibility of reaching a 2°C climate change limitation target (IEA 2011; NRC 2009a). According to the international scientific community, power generation needs to be “decarbonized” – be produced without a net CO2 increase in emissions – and overall energy efficiencies will need to increase. Energy-efficiency goals, discovery of new domestic fuels, and transmission grid issues, as well as reducing demand and thus deferring construction of new supply, are central concerns for any energy transformation scenario. These considerations need to be viewed within the scenario that US electricity demands are expected to increase by 35 per cent by 2030 (EIA 2012a).
