Energy efficiency: how far does it get us in controlling climate change?

Abstract

The Fourth Assessment Report (AR4) of the Nobel Peace Prize-winning Intergovernmental Panel on Climate Change (IPCC) has served as a landmark document to influence humanity’s battle against climate change. It was the AR4 that first declared that there is a “very high confidence” that “the global average net effect of human activities” since the industrial revolution “has been one of warming”, and that warming of the climate system is by now “unequivocal”(IPCC 2007a). In addition, it established that most of the observed increase in global average temperatures in the last five decades is very likely due to anthropogenic influence, i.e. to the observed human-caused increase in greenhouse gas concentrations. Depending on the rate of change in greenhouse gas emissions, global mean temperature will continue to rise between 1°C and 6°C as compared to 1990–2000 levels (IPCC 2007a). The IPCC AR4 and several other studies published thereafter have clearly demonstrated that with warming of several degrees above current levels, dramatic ecological, agricultural, economic and social damages will be happening (IPCC 2007b; SEG 2007; Stern 2006). The AR4 has identified the emission reductions needed to stabilize warming at certain levels (Fig. 1, IPCC 2007c). The figure demonstrates that in order to cap warming at a level such as the one defined by the European Union and the UN Scientific Expert Group on Climate Change (European Commission 2007; SEG 2007), i.e. at 2 C above pre-industrial levels, the task is huge. In order to stay below this temperature level, global CO2 emissions will need to peak before 2015, and they will need to be reduced by 50–85% of their 2000 levels by 2050 (see Fig. 1), as compared to the 25–90% increase projected for 2030 if no further climate measures are taken (IPCC 2007c). Even to meet a 2.4–2.8°C warming target level, they still need to be reduced by 30–60%. When one considers the significant challenges governments have gone through in order to meet their 0–8% reduction targets as mandated by the Kyoto Protocol, reductions in the order of 50–85% seem undoable at first sight. However, another very important finding of the Fourth Assessment report is that “the range of stabilization levels assessed can be achieved by deployment of a portfolio of technologies that are currently available and those that are expected to be commercialized in coming decades”. The reason is that over a period of 40 years replacing the existing energy supply infrastructure with low carbon energy sources and a large part of the transportation system, building stock and industrial equipment with highly efficient alternatives is feasible, while short term changes are much more difficult Energy Efficiency (2009) 2:87–94 DOI 10.1007/s12053-009-9049-7