What do the Appendices to the Copenhagen Accord tell us about global greenhouse gas emissions and the prospects for avoiding a rise in global average temperature of more than 2°C?
This paper sets out an assessment of the latest targets and intended actions for reducing emissions of greenhouse gases, which have been submitted by countries to the Appendices of the Copenhagen Accord.
These targets and intended actions are quantified and assessed in terms of global emissions to provide an understanding of the extent to which planned actions are consistent with a path towards avoiding a rise in global average temperature of more than 2°C 2, which is specified in the Accord.
The latest studies of the science and economics conclude that annual global emissions of greenhouse gases must peak and fall to around 40 to 48 billion tonnes of carbon dioxide-equivalent in 2020 to be consistent with a reasonable (i.e. 50 per cent) chance of limiting the increase in global average temperature to no more than 2°C by the end of this century. This finding is in line with the earlier work that underpins the conclusions of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. A ‘climate responsible’ level of global emissions in 2020, reflecting both costs and risks, would be nearer to 44 billion tonnes5.
Our analysis suggests that, although the targets and intended actions are substantial, they would not be enough to limit annual emissions to 44 billion tonnes in 2020, but would collectively imply global annual emissions of about 48.2 to 49.2 billion tonnes. This level of emissions would represent a reduction of 6.7 to 7.7 billion tonnes compared with the associated ‘business as usual’ forecast for emissions in 2020 of 55.9 billion tonnes.
Emissions in 2020 of about 48 billion tonnes would mean that greater and more costly emission reductions of around 4 per cent each year would be required after 2020 for a path that would just about have a reasonable chance of avoiding a temperature increase of more than 2°C 7. Hence those targets and intended actions that have been submitted to the Copenhagen Accord would not make it impossible to have a reasonable chance of avoiding a temperature rise of more than 2°C, but it would make it significantly more difficult and costly.
The recent economic slowdown should make emissions targets less difficult to meet, but should mean that bigger cuts are achieved. Given that annual global emissions are currently estimated to be about 47 billion tonnes and growing, any path that has a reasonable chance of meeting the 2°C goal includes a peak within the next 10 years and further reductions afterwards.
This analysis depends on a number of key assumptions that are subject to uncertainty and risks that apply to our estimates for mitigation:
Countries achieve their specified goals for emissions, including those that are conditional on the actions of others;
- Double-counting is avoided that could arise if financial support for offsetting emissions by one country is used to support another country in delivering its target;
- Widespread double-counting, or some other failure to deliver national targets (possibly linked to lack of financial support), could lead to additional emissions of 1 to 2 billion tonnes in 2020;
- Surplus emissions allowances from previous commitment periods do not weaken future mitigation efforts. Allowances could lead to additional emissions of up to 1 to 2 billion tonnes in 2020, depending on how many are used to offset mitigation action;
- A system of rules is adopted for accounting for greenhouse gases released and absorbed in the Land Use, Land Use Change and Forestry (LULUCF) sector to ensure the environmental integrity of targets while providing incentives to reduce emissions and increase sinks in these sectors. Depending on interpretation and rules, this uncertainty could be equivalent to around +/-1.5 billion tonnes of emissions in 2020;
- Developing countries grow broadly in line with their aspirations. Some uncertainty remains around emissions by developing countries, as the estimates are based on actions to reduce emissions relative to ‘business as usual’ levels. If economic growth or the carbon intensity of growth significantly exceeds expectations, emissions will be higher. Conversely slower or cleaner growth patterns would lead to lower emissions. This uncertainty could be equivalent to around +/-2 billion tonnes in 2020.
Collectively this represents a risk of adding 2 to 4 billion tonnes to the total for 2020, and additional uncertainty of +/-3.5 billion tonnes. This highlights the importance of tackling the uncertainties and avoiding the risks that could undermine mitigation. Failure by Annex I countries to deliver their targets, or even lower assumptions about delivery by non-Annex I countries than set out above, could lead to higher emissions in 2020.
Adopting a different approach or different assumptions, including underlying ‘business as usual’ estimates, can lead to different findings. Although other modelling groups have reached different conclusions, most other studies have produced estimates that are in line with ours.
There is some scope for achieving further reductions, for instance by capping emissions from international aviation and shipping and by stronger national actions. The Copenhagen Accord also set the goal of mobilising financial support of US$100 billion per annum by 2020, and US$30 billion between 2010 and 2012, to address the needs of developing countries.
A High-Level Advisory Group on Mobilising Climate Change Resources has been launched by the United Nations Secretary-General to explore how such funding could be raised. While much of this money will be used to support adaptation and wider capacity-building, a significant portion could support the transition by developing countries to low-carbon economic growth, including by protecting forested areas. Although some of this may provide support for the delivery of actions that are already planned, it could also fund greater ambition beyond existing unilateral targets and lead to a reduction in emissions, compared with ‘business as usual’ levels, by poorer countries that do not currently have mitigation actions included in the Appendix to the Copenhagen Accord – this could include action to reduce emissions from deforestation and land degradation.
Overall, the achievement of the targets and the realisation of the intentions submitted to the Appendix of the Copenhagen Accord would represent a big step away from ‘business as usual’ emissions, and could be consistent with a slow start on a path to a 2°C goal. However, policy makers could reduce the overall difficulty and cost of meeting the 2°C goal if they find ways to achieve stronger emission reductions by 2020. Further reductions of about 3 to 5 billion tonnes in annual emissions by 2020 would be required to reach a ‘climate responsible’ level of 44 billion tonnes.
Whatever emissions level is reached in 2020, strong reductions will be required subsequently to have a reasonable chance of avoiding a rise in global average temperature of more than 2°C.
Nicholas Stern and Christopher Taylor