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Side Event at Bonn UNFCCC negotiations on 2°C

Emissions in Line with Staying Below 2°C – Do Current Proposals Make It?

Report by ENB on the side:

Presented by Potsdam Institute for Climate Impact Research

This panel addressed the implications of current and proposed emission reductions for global temperature levels, with an emphasis on methodological details of scientific studies.

Katja Frieler, Potsdam Institute for Climate Impact Research (PIK), analyzed emission targets for limiting global warming to 2°C by 2100. She said cumulative emissions of 1 trillion tons of carbon dioxide (CO2) between 2000 and 2050 would result in a 25% probability of exceeding the 2°C limit, and noted that a third of that amount has already been produced over the last nine years.

Sarah Raper, Manchester Metropolitan University, discussed the effects of aviation on global temperature change. She described aviation as one of the most rapidly growing sources of CO2 emissions, noting that its contribution to global temperature change exceeded that of the UK. She added aviation is expected to contribute more than 20% to global CO2 emissions and 15-20% to global temperature change by mid-century.

Joeri Rogelj, PIK, analyzed the implications of current country positions on emissions growth. He presented trajectories of national emissions using scenarios based on official national policy proposals, including: Canada’s plan to cut its 2006 emissions by 20% by 2020; the EU targets of a 30% cut by 2020 and a 95% cut by 2050 based on 1990 emissions; and India’s goal not to exceed Annex I countries’ per capita emissions. Rogelj highlighted results from a study that projected future greenhouse gas (GHG) concentrations and temperatures based on current country positions. He said the study found virtual certainty of exceeding 550 parts per million (ppm) CO2 equivalent (CO2 eq) and a 2°C temperature increase by 2100. Rogelj reported median projections resting instead at 700 ppm CO2 eq and 3°C by 2100, respectively.

Bill Hare, Climate Analytics, discussed the connection between cumulative emissions and the probability of exceeding a temperature increase of 2°C. He emphasized the urgency of substantive emission reductions. He stressed that less than a quarter of the economically recoverable fossil fuels cannot be used without reaching the 2°C limit, and noted an 87% probability of exceeding the limit if global GHG emissions increase by more than 25% above 2000 levels by 2020.

Participants raised questions regarding the underlying methodological assumptions of the studies presented, including the effects of water and forestry on temperature increases, and the role of offsets, supersonic aircraft and carbon capture and storage on emission levels.

L-R: Katja Frieler, PIK; Bill Hare, Climate Analytics; Sarah Raper, Manchester Metropolitan University; and Joeri Rogelj, PIK.


Katja Frieler, PIK, said 100 countries have called for limiting temperature increases below 2ºC, and said this goal can be reached only if less than a quarter of economically recoverable fossil fuel reserves are used. Sarah Raper, Manchester Metropolitan University, said that in 2005 aviation contributed 2.8% to global CO2 emissions and 4.7% to global temperature change. Joeri Rogelj, PIK, discussed projected emissions growth in various countries, given official national action plans, including China’s plan to reduce its emissions per GDP ratio by 20%.

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