‘Fair and ambitious’, but not in a 2°C world

Countries have been submitting their emission pledges (Intended Nationally Determined Contributions, INDCs), in the lead up to the Paris Conference of the Parties (COP21) in December. Countries have been requested to show that their pledges are ‘fair and ambitious’ and contribute to keeping global temperatures below 2°C above pre-industrial levels.

A new study, led by Glen Peters from the Center for International Climate and Environmental Research – Oslo (CICERO), has found that the emission pledges from the three largest emitters, China, USA and Europe leave very little room for other countries to emit in 2°C world.

“As you’d expect, all countries claim their pledge is ‘fair and ambitious’”, said Peters, “but the pledges from the US, EU, and China use most of the remaining carbon budget, leaving virtually no room for others to emit”.

Countries were asked to show their pledges were ‘fair and ambitious’, but no guidelines were given on how to make such an assessment.

 “We have assessed fairness and ambition using the ‘cumulative emissions’ approach highlighted in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change”, said Peters.

The cumulative emissions approach shows that a fixed amount of CO₂ can be emitted to keep temperatures below 2°C. Given the amount of CO₂ already emitted, the remaining amount of CO₂ is about 800 GtCO₂, which is about 25 years of current annual emissions. Fairness is transparently assessed by sharing this amount to countries.

The US and EU pledges take a large share of the remaining emissions: a share greater than their share of current global emissions, and much greater than their share of global population. The share of emissions associated with China’s pledge is much greater than both China’s share of current emissions and population.

For the pledges of the EU and US to be ‘fairer’ they would need to accelerate ongoing emission reductions, while China must peak its emissions and start the process of decarbonisation already begun by developed countries.

“The US and EU have both been reducing emissions in the last 10 years, and their pledges require an acceleration of existing reductions”, said Peters. “The challenge is harder for China since emissions must first peak and then decline at a rate faster than in the EU and US”.

“The strength of the cumulative emission approach is that the allowable carbon emissions are fixed for a given temperature target” said Robbie Andrew, a co-author also based at CICERO. “This leads to a simple arithmetic: the more one country emits, the less others can emit”.

“The EU, US, and Chinese emissions use so much of the remaining carbon budget, that the rest of the world can emit virtually nothing by 2030”, said Andrew. “The simple arithmetic leaves two options: either aim for a higher temperature target or strengthen the current emission pledges.”

With China's emissions currently so high, some quarter of the global total, they are very rapidly using up any remaining quota that might be assigned them. “Even if China were to plateau this year, they'd continue to use up this quota very rapidly,” said Peters.

Almost all scenarios assessed by the IPCC that were compatible with the 2°C target made use of so-called negative-emissions technologies, such as bioenergy combined with carbon capture and storage, which are still a long way from large-scale commercialisation.

According to Pierre Friedlingstein, a co-author at the University of Exeter, “If we follow the submitted pledges, we will be gambling our future on unproven, large-scale deployment of negative-emissions technologies. This seems like a Faustian bargain to me.”

While the pledges are an important step forward, Susan Solomon, a co-author from the Massachusetts Institute of Technology, says the analysis shows research and development needs to rapidly accelerate. “Promises won’t get us there on their own: a shared global commitment to speed up development and deployment of a wide range of energy technologies is what the world needs now,” said Solomon.

The study compares emission pledges using carbon dioxide emissions to be consistent with the cumulative emission approach and excludes deforestation as it sufficient country-level data is not available. The paper shows results detailed for the EU, US, and China, but the method can be applied to any emission pledge.