Comparison of top-down and bottom-up estimates of sectoral and regional greenhouse gas emission reduction potentials
The amount of greenhouse gas emissions that can be avoided at costs below a certain level plays a key role in climate policy analysis. Estimates of economic reduction potentials (the amount of greenhouse gas emissions that can be reduced at different costs levels) are, however, complicated by uncertainty in several dimensions: uncertainty about the costs of different technologies and their development over time and uncertainty about the interaction of the energy sector with the rest of the economy. A wide range of models has been developed that treat these aspects of uncertainty in different ways and provide insights into emission reduction potentials under their respective assumptions. The models are developed from various scientific paradigms, which may lead to different interpretations of the past and different expectations of the future. A main cleavage is between models that are rooted either in a macro-economic tradition (top-down) or in an engineering tradition (bottom-up).
Abstract
The Fourth Assessment Report of IPCC reports that greenhouse gas emissions can be reduced by about 30–50% in 2030 at costs below 100 US$/tCO2 based on an assessment of both bottom-up and top-down studies. Here, we have looked in more detail into the outcomes of specific models and also analyzed the economic potentials at the sectoral and regional level. At the aggregated level, the findings of the IPCC report are confirmed. However, substantial differences are found at the sectoral level. At the same time, there seems to be no systematic difference in the reduction potential reported by top-down and bottom-up approaches. The largest reduction potential as a response to carbon prices exists in the energy supply sector. Reduction potential in the building sector may carry relatively low costs. Although uncertainties are considerable, the modeling results and the bottom-up analyses all suggest that at the global level around 50% of greenhouse gas emissions may be reduced at carbon price (costs) below 100$/tCO2-eq—but with a wide range of 30–60%. At a carbon price (costs) less than 20$/tCO2-eq, still 10–35% of emissions may be abated. The variation of results is higher at low carbon-price levels than at high levels.
Authors
Specifications
- Publication title
- Comparison of top-down and bottom-up estimates of sectoral and regional greenhouse gas emission reduction potentials
- Publication date
- 1 December 2009
- Publication type
- Publication
- Magazine
- Energy Policy 2009; 37(12):5125-39
- Product number
- 92421