GHG abatements in the 450 Core Accelerated Action and 450 Core scenarios compared to the Baseline, 2020 and 2030
--- The implications of achieving the 450 Accelerated Action scenario ---
Both the 450 Accelerated Action and the 450 Core scenarios reduce the projected Baseline emissions
by more than 75% by 2050. T...
he main difference between the two scenarios is the timing of global
mitigation efforts in the next two decades. These result in differences in which gases are reduced most (or
which fuel in the case of energy-related CO2 emissions), as well as different regional and sectoral
mitigation choices. These elements are illustrated in the four panels of Figure 3.20. Of course, the larger
mitigation efforts in the 450 Accelerated Action scenario imply lower environmental risks but higher costs
than the 450 Core scenario. By 2030 carbon prices would be about 50% higher in the 450 Accelerated
Action scenario than in the 450 Core.
In aggregate terms, both scenarios lead to very similar emission reduction patterns across regions,
given the shared permit allocation rule. BRIICS countries account for about half of the total mitigation
effort, the other half being split evenly between OECD and RoW countries. However, the analysis of
country details reveals larger differences across scenarios: China and the Middle East account respectively
for about one-third and 7% of total mitigation in the 450 Accelerated Action scenario, and are more
sensitive to the targeted emission level in 2020. In other countries, such as India, mitigation efforts depend
less on the scenario architecture because the mitigation potentials in these countries are less sensitive to the
carbon price level around the years 2020 and 2030.
In both simulations, the lowest cost mitigation options are mobilised in the early stages of action,
irrespective of the carbon price level. The level of ambition then determines the optimal mix of reduction
measures. Non-CO2 GHGs (methane, nitrous oxide and fluorinated or “F gases”, such as HFCs, PFCs and
sulphur hexafluoride – SF6) have sizeable mitigation potential and reductions can be achieved at moderate
cost. These potentials could be tapped into even under modest carbon prices. For example, easily adjusted
industrial activities and changes in agricultural practices are projected to help reduce large volumes of
methane efficiently (e.g. in coal mining, oil and gas processing and shipping; waste recycling and methane
capture from landfills). Methane mitigation alone accounts for more than 60% of the total reduction of
non-CO2 gases by 2020. The reduction of nitrous oxide arising from changes in rice cultivation patterns,
acid production or nutrient management, covers another 20%.
Accelerated action would require a quicker decarbonisation of electricity production, while a more
gradual response to climate change would require relatively more effort from energy intensive industries,
services and agriculture. In both scenarios, oil is the fossil fuel affected the most over the coming decade.
Coal use is particularly discouraged for power generation and even moderate carbon prices are enough to
trigger efficiency improvements in coal-based electricity generation and to favour a switch towards gasbased
production capacity that is less carbon-intensive, notably in China and India. Natural gas is affected
evenly in both scenarios and represents about 20% of total reduction in 2020 and 2030. In both scenarios,
gas acts as a bridging fuel until lower carbon technologies become available on a large scale. Nuclear
energy is projected to supply almost two-thirds of low-carbon electricity in 2020 and only half of it by
2030 in both cases. The share of hydro electricity tends to diminish over time as wind, solar and other nonhydro
renewables take over. However, the carbon price differential between the two scenarios is not significant enough to drive notable changes in the mix of renewable technologies by 2030. Finally, fossil
fuel based electricity generation with CCS plays a significant role later in the projection period (see
Box 3.10 on the implications of technology options).