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A Conceptual Framework to Assist Decision Making on International Climate Change Policy: Discussion Paper

Conceptual framework

Decision 1: Global stabilisation goal

Decision 2: Global cap/emission reducing strategy

Decision 3: The rules

Decision 4: The New Zealand cap

Decision 5: The New Zealand ETS

Impacts on NNW

Likely scenarios and implications for negotiations

Initial recommendations for further work

Decision 2: Global cap/emission reducing strategy

Stabilising concentrations at these levels will require large cuts in global emissions, relative to BAU. While the figures in table 1 only relate to CO₂ emissions (and assume non-CO₂ emissions grow at BAU), the approximate range of CO₂ reductions that would need to be achieved by 2050 is between 30 and 85% below 2000 levels. This is reasonably consistent with conclusions of the Stern Review, which found that stabilising at around 550ppm CO₂-e would require global emissions of all GHGs to be around 25% below current levels by 2050, and to get to 450ppm, without overshooting, global emissions would need to reduce by 70% below current levels by 2050⁸. Taking the average of Stern’s range (~50%) and relating it to 1990 levels, there would need to be a 35% reduction below 1990 levels of global GHGs by 2050⁹.

There is also a range of medium-term (2020-30) global emissions reduction targets that are required, and given that this is the likely timeframe in which negotiations will be made, this period will be the focus of this paper. As with any long-term goal, there are a number of ways of progressing towards it in the short to medium term. Figure 2 illustrate the range of possible reduction pathways for global CO₂ emissions, to ensure concentrations stabilise between 440-535ppm.

To stabilise GHG concentrations at around 450-535 ppm would therefore require ‘CO₂-only’ emissions in 2020 and 2030, to be on average about 24 and 21.5 GT/year respectively¹⁰. Relating these ‘CO₂-only’ emissions to 1990 levels, stabilising emissions in this range would require a 15% reduction compared to 1990 levels by 2020 and a 20% reduction on 1990 levels by 2030¹¹.

There have been a range of other studies that have addressed multi-gas (all GHGs) reduction scenarios. In these scenarios reductions in both CO₂ and non-CO₂ GHG emissions can be used to meet any mitigation pathway, which means on average the absolute reductions in CO₂-only gases are less. To achieve stabilisation at around 550ppm it has been estimated that global emissions in 2025 would need to be no higher than 25% above 1990 levels¹². To stabilise emissions at the lower end of the spectrum by 2025 (i.e. 450ppm) would require greater cuts in emissions. A synthesis of studies by the Dutch environmental agency has modelled the global reductions required by 2020 to ensure concentrations are stabilised somewhere in the range of 450-550ppm, and found that global GHG emissions in 2020 need to be no more than 25% above 1990 levels¹³.

While all of the above data refers to global emission reduction targets, it is important to determine what share of responsibility is placed on developed and developing countries to reduce their emissions. It is clear that the majority of current concentrations in the atmosphere are due to developed countries, and over the short term emissions from the developed world will continue to be greater than the developing world. Figure 3 illustrates global emissions under a BAU scenario, and compares this with the emission levels required to stabilise between 450-550ppm.

As discussed, to reduce global emissions to ensure the ‘stabilisation’ scenario above, developed countries will need to take on more responsibility than developing countries. The precise share of this responsibility is difficult to quantify, however it will be essential that during the negotiations a decision is made on when, and how, a developing country can be integrated within either the developed countries’ cap, or any voluntary commitment to reduce emissions. New Zealand should therefore support the ‘Russian Proposal’, which aims to develop guidelines by which developing countries can be integrated into the global emission reducing strategy.

Assuming that under this Proposal developing countries do not face any emission reduction targets, but do have some deviation below BAU, and that all major developed countries and all GHGs are included in the cap¹⁵, to ensure that the global stabilisation target is met, developed countries would be required to emit about 25% below 1990 levels by 2020. This would require approximately 10GT/year emission reductions in 2020, and on average about 6GT/year between 2013 and 2020.

The IPCC have reached similar conclusions to those illustrated in figure 4, and recently stated that developed countries as a group would need to reduce their emissions significantly by 2020 (10–40% below 1990 levels) and to still lower levels by 2050 (40–95% below 1990 levels), to stabilise concentrations between 450-550ppm¹⁶. To ensure the lower end of the stabilisation target is achieved (450ppm), a 25-40% reduction below 1990 levels by 2020 is required¹⁷. In August 2007, the UNFCCC recognised the IPCC recommendations that developed countries need a 25-40% reduction on 1990 levels by 2020, and that this range laid the groundwork for the Bali Conference¹⁸.

The above analysis has provided an approximate amount of emission reductions that are required by participating countries each year between 2013 and 2020, to ensure that global concentrations are stabilised between 450-550ppm. It is important to note that the analysis does however assume full participation from all developed countries, and contributions from developing countries. The following section on rules will, in part, discuss the outcomes where this assumption does not hold.

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