Among the industrialized regions, the MAC curve for the USA has the mildest slope. At the cost of $800/tCO2-eq, the reduction rate relative to 1990 reaches about 90 % in the USA, whereas those

of EU27 and Japan reach about 70 %. The variance of the reduction rate among different regions stems from differences in the reference emissions, technology performance and availability (including renewable energy, CCS), energy and non-energy service demand selleck inhibitor structures, energy price, etc. Figure 7 indicates that the GHG emission reduction target of 50 % relative to 1990 is achievable at a marginal learn more cost of $600/tCO2-eq. If we assume the same MAC—$600/tCO2-eq—across the world, GHG emissions in 2050 end up at −85 % in the USA, −66 % in the EU, −70 % in Japan, −13 % in China, and +47% in India, compared to the 1990 level. Next, we want to determine which emission reductions in 2020 are consistent with the 2050 target. According to the GHG price path scenarios, the GHG price of $150/tCO2-eq in 2020 corresponds to the GHG price of $600/tCO2-eq in 2050 (see Fig. 4).

Therefore, the reduction check details rate at $150/tCO2-eq in 2020 is consistent with the 2050 target. At $150/tCO2-eq, global GHG emissions increase by 6 % in 2020 relative to the 1990 level. The changes of regional GHG emissions at $150/tCO2-eq in 2020 relative to 1990 differ significantly among regions: −17 % in the USA, −25 % in the EU27, −12 % in Japan, +99 % in China, and +65 % in India. Note that these values include only domestic GHG emissions

and do not include carbon credit, which is traded internationally. Thus, the values do not correspond directly to regional emission targets, as the emission targets might include carbon credit. Fig. 7 Estimated MAC curves for major regions in 2020 and 2050. The horizontal axis indicates the rate of GHG emission change Immune system relative to 1990. A negative value denotes a reduction and a positive value denotes an increase relative to 1990 Transition scenario for achieving a 50 % reduction by 2050 In this section we present the s600 scenario in which GHG emissions in 2050 are reduced by 50 % relative to the 1990 level, with a focus on dynamic changes in global GHG emissions and energy systems. GHG emission path In the s600 scenario, global GHG emissions become 40 GtCO2-eq in 2020 and 19 GtCO2-eq in 2050, values that correspond to +6 and −50 % of the 1990 levels, respectively (Fig. 8). Compared to the reference scenario, a significant GHG emission reduction is required in the s600 scenario: the rates of GHG emission reduction from the reference scenario are 23 % in 2020 and 73 % in 2050. The average annual rate of GHG emission reduction from 2005 to 2050 in the s600 scenario is 1.9 %. Fig. 8 Global GHG emissions in the reference and the s600 scenarios A decomposition analysis will help us understand, from a macroscopic viewpoint, how that rapid emission reduction is achieved in the s600 scenario.