An objective way to decide on a fair Australian emissions pledge

Earlier this year, Australia was handed a list of 36 questions about its climate policy from the United States, China, Brazil, New Zealand, the European Union and Switzerland as part of the ongoing United Nations climate negotiations.

Many of them, such as Brazil’s enquiry as to whether Australia will “increase its level of ambition”, appear to be challenging Australia to show more commitment.

To its credit, the Abbott government has been holding a public consultation on the question of what its post-2020 emissions target should be. It has also been also asking for our views on the impact of that target on Australia, and on whether more policies should be considered in addition to the current Direct Action plan.

Australia, like other nations, is preparing policies for the Paris climate talks in December this year. Each nation will bring to Paris its post-2020 climate pledge, or “Intended Nationally Determined Contribution”. Many nations have already released theirs.

What should Australia’s pledge be?

In my submission to the public consultation, I recommended that Australia’s post-2020 target should be calculated on the basis of its fair share of the global carbon budget – the science-based estimate of the maximum amount of emissions we can release without overshooting the world community’s agreed 2-degree climate goal.

Nations need to focus on the global carbon budget, not on what their neighbours are doing

Governments, including Australia, made this 2-degree commitment at the 2010 Cancun climate summit, pledging to make the deep cuts in global greenhouse gas emissions required to limit global warming to less than 2-degrees hotter than the pre-industrial average planetary temperature.

The Intergovernmental Panel on Climate Change has estimated that the global carbon budget to give us a 50% chance of limiting global warming to less than 2-degrees is just over 3 trillion tonnes (3,009 gigatonnes, to be precise) of carbon dioxide. Some 1,890 Gt of CO2has been “used up” so far, leaving us a remaining 1,119 Gt of CO2 that the world can emit before we blow the overall budget.

However, the current trajectory of global greenhouse gas emissions will take us far beyond this target. The planet is on course for an average temperature rise of between 3.2C and 5.4C above pre-industrial times by 2100.

The carbon budget carve-up

A key issue for the Paris agreement is how the budget should be allocated. It is hard to imagine the international community agreeing to the usable global carbon budget being arbitrarily distributed among the world’s nations. Pragmatically, to gain widespread support, it will have to be done in ways that are transparent, fair and grounded in international legal principles.

Of the countries that have submitted INDCs to date, pledges take the form of a percentage reduction by a certain point in time. For example, the European Union has committed to a binding target of at least a 40% domestic reduction in greenhouse gas emissions by 2030 compared to 1990. The United States has pledged to reduce its greenhouse gas emissions by 26-28% below its 2005 level by 2025.

Unfortunately, no standard approach has been taken, so the baseline and target years vary and do not cover the full time period over which emissions will have to be reduced. What will the EU do after 2030, and the United States after 2025? We need commitments for the full contraction period over which emission reductions must occur.

We need to know the implications of these pledges for developing countries. How much is left for them in the global carbon budget after the appropriations by the EU and United States implied by their INDC pledges? We also need to know if the pledges are sufficient, in aggregate, to meet the 2-degree target.

To answer these questions we need an approach that requires everyone to refer back to the usable global carbon budget. Otherwise, among other things, any single nation’s commitment, Australia’s included, will risk being judged as effectively arbitrary and scientifically indefensible.

Contract and converge

One approach, called “contraction and convergence”, is based on the proposition that each human being has equal rights to the ecosystem services provided by the global commons – in this case, the carbon-absorbing capacity of the Earth system (consistent with Article 1 of the Universal Declaration of Human Rights).

A simple per capita distribution of the usable global carbon budget would meet with opposition because of the huge existing differences in per capita emissions between countries. The contraction and convergence approach deals with this by requiring countries to agree on a specified time period (for instance by 2040) over which they converge on an equal level of per capital emissions.

At the same time, overall global emissions will contract by an agreed year (perhaps 2080) with the aim of collectively staying within the usable global carbon budget.

According to one estimate, if Australia’s emissions target was determined on this basis, meeting the 2-degree Cancun commitment would require emissions reductions of around 90%, relative to 2000 levels, by 2050. According to my indicative calculations, assuming a contraction period from 2010-2110 and convergence of per capita emissions from 2020 to 2050, Australia’s share of the usable global carbon budget would be about 8.96 Gt of CO2– or roughly 16 years’ worth of its current emissions.

By comparison, the Australian government’s current target (a 5% reduction relative to 2000 levels by 2020) calls for a total reduction in emissions of just 0.236 Gt of CO2 – less than one year’s worth of Australia’s current emissions.

Deeper cuts needed

However you slice it, Australia needs to make deep and permanent cuts in its greenhouse emissions to meet its fair share of the 2-degree Cancun commitment. Given Australia’s economic dependence on fossil fuels, for both electricity generation and export earnings, meeting this commitment clearly presents a significant economic challenge.

Australia is at a critical juncture. It can choose to ignore the 2-degree commitment and simply adopt an arbitrary mitigation target that suits its short-term economic national interests. Or it can choose a mitigation target that is justifiable and consistent with its fair share of the global carbon budget.

An arbitrary, self-serving target would necessitate special pleading with the international community at the Paris climate talks, and would be certain to prompt plenty more critical questions from other countries.

 Prof Brendan MackeyAUTHOR

Professor Brendan Mackey