IPCC Fourth Assessment Report: Climate Change 2007
Climate Change 2007: Synthesis Report

5.6 Costs of mitigation and long-term stabilisation targets

The macro-economic costs of mitigation generally rise with the stringency of the stabilisation target and are relatively higher when derived from baseline scenarios characterised by high emission levels. {WGIII SPM}

There is high agreement and medium evidence that in 2050 global average macro-economic costs for multi-gas mitigation towards stabilisation between 710 and 445ppm CO2-eq are between a 1% gain to a 5.5% decrease of global GDP (Table 5.2). This corresponds to slowing average annual global GDP growth by less than 0.12 percentage points. Estimated GDP losses by 2030 are on average lower and show a smaller spread compared to 2050 (Table 5.2). For specific countries and sectors, costs vary considerably from the global average.[33] {WGIII 3.3, 13.3, SPM}

Table 5.2. Estimated global macro-economic costs in 2030 and 2050. Costs are relative to the baseline for least-cost trajectories towards different long-term stabilisation levels. {WGIII 3.3, 13.3, Tables SPM.4 and SPM.6}

Stabilisation levels (ppm CO2-eq)  Median GDP reductiona (%)  Range of GDP reductionb (%)  Reduction of average annual GDP growth rates (percentage points) c,e 
 2030  2050  2030  2050  2030   2050 
445 – 535d   Not available  < 3  < 5.5  < 0.12   < 0.12  
535 – 590  0.6  1.3   0.2 to 2.5  slightly negative to 4  < 0.1   < 0.1 
590 – 710  0.2  0.5  -0.6 to 1.2  -1 to 2  < 0.06   < 0.05 


Values given in this table correspond to the full literature across all baselines and mitigation scenarios that provide GDP numbers.

a) Global GDP based on market exchange rates.

b) The 10th and 90th percentile range of the analysed data are given where applicable. Negative values indicate GDP gain. The first row (445-535ppm CO2-eq) gives the upper bound estimate of the literature only.

c) The calculation of the reduction of the annual growth rate is based on the average reduction during the assessed period that would result in the indicated GDP decrease by 2030 and 2050 respectively.

d) The number of studies is relatively small and they generally use low baselines. High emissions baselines generally lead to higher costs.

e) The values correspond to the highest estimate for GDP reduction shown in column three.

  1. ^  See Footnote 24 for further details on cost estimates and model assumptions.