Present commitments to limit carbon emissions – even if fully implemented – will not succeed in keeping global temperature rises below 2ºC by 2100. Nor can temperatures be kept below the 2ºC limit without new technologies such as carbon capture and storage.

These are some of the findings by researchers from Europe, China, India, the US and Japan as part the EU-funded LIMITS project.

The project integrated and assessed economic, financial, energy and climate data to model the consequences of possible outcomes of global climate talks in Paris, France in 2015. The researchers aimed to help leaders understand the costs and benefits of their positions and reach agreement on how to limit global temperature rises to below 2ºC.

The team entered data for various scenarios. These range from a successful outcome to negotiations in Paris in 2015 resulting in a strict global agreement on emission limits from 2020 (preceded by preparatory actions across the world), to complete failure and reliance on fragmented and regional actions to limit emissions. The models generated possible policy ‘pathways’ that show their probable climate effects, costs and risks.

Certain policy pathways failed to keep temperatures below 2ºC by 2100, whatever the circumstances. These findings can be considered particularly robust, according to project coordinator Massimo Tavoni, an economist at Fondazione Eni Enrico Mattei in Italy.

Policy pathways that could emerge from the success or failure of the Paris talks were central to the modelling by the LIMITS team. The negotiation agenda agreed at the Durban Climate Conference in 2011, known as the ‘Durban Platform‘, will be the basis for climate discussions in Paris.

The Durban Platform agenda includes: a 2ºC global temperature limit as a target; seeking the inclusion of emerging nations as well as developed ones in legally binding targets; and a strong focus on regional and national climate action.

Potential policy pathways following Paris could include a cap on global emissions of either 450 parts per million (ppm) or possibly 500 ppm. The LIMITS team also took account of:

• the effects of mitigation actions prior to any global agreement;
• the possibility of a ten-year delay before global agreement, or;
• how the temperature rise could be kept below 2ºC through fragmented actions in the event of failure to reach global agreement.

Certain policy pathways have dramatic effects. It is clear that delayed action on reducing carbon emissions – even just ten years’ delay – greatly increases the costs of limiting temperature rises to 2ºC, notes Tavoni.

The longer the delay before mitigation starts, the greater the lock-in of global economies to fossil fuels, and the greater the transition cost, the research revealed.

And limiting global temperature rises will be extremely difficult without global agreement to place a price on carbon. The European Union has led the way in global climate change talks, pledging to cut its greenhouse gas emissions by 20% by 2020 compared to 1990 levels.

The agreement this year to increase this emissions target to 40% by 2030 shows the EU’s continued commitment to cutting carbon emissions. The EU is pushing hard for a global agreement in Paris.

Collaborative learning

The project highlighted important co-benefits and trade-offs between climate change mitigation and other national priorities, such as air quality and energy security.

It also added detail on the impacts of various policy pathways at a national and regional level. There is a tendency to discuss the impacts of climate change at a global level, as if the impacts of climate and energy policies would be felt uniformly, says Tavoni.

In fact, the effects will vary significantly across industries and regions, and the modelling brought this out.

The LIMITS project will provide negotiators at the Paris conference with scientifically based forecasts of the likely outcomes from the various policy pathways they are considering. Here, the international make-up of the LIMITS team had additional benefits, says Tavoni.

When the climate negotiations start in Paris in 2015, the negotiators will be very conscious of their national responsibilities. Every concession carries the risk of competitive disadvantage.

The LIMITS project provided an opportunity for leading researchers from the major carbon-emitting regions of the world to come together in an open and collaborative way, to learn from each other and to gain a joint understanding of the challenges and opportunities that the world is facing, he adds.

Contribution of EU-funded research to IPCC's 5th Assessment Report  - Memo 31/10/2014