Abstract
Global policy targets for greenhouse gas emissions reductions are being negotiated. The amount of emitted carbon dioxide remaining in the atmosphere is controlled by carbon cycle processes in the ocean and on land. These processes are themselves affected by climate. The resulting ‘climate–carbon cycle feedback’ has recently been quantified, but the policy implications have
not. Using a scheme to emulate the range of state-of-the-art model results for climate feedback strength, including the modelled range of climate sensitivity and other key uncertainties, we analyse recent global targets. The G8 target of a 50% cut in emissions by 2050 leaves CO2 concentrations rising rapidly, approaching 1000 ppm by 2300. The Stern Review’s proposed
25% cut in emissions by 2050, continuing to an 80% cut, does in fact approach stabilization of CO2 concentration on a policy-relevant (century) timescale, with most models projecting concentrations between 500 and 600 ppm by 2100. However concentrations continue to rise gradually. Long-term stabilization at 550 ppm CO2 requires cuts in emissions of 81 to 90% by 2300, and more beyond as a portion of the CO2 emitted persists for centuries to millennia.
Reductions of other greenhouse gases cannot compensate for the long-term effects of emitting CO2.
not. Using a scheme to emulate the range of state-of-the-art model results for climate feedback strength, including the modelled range of climate sensitivity and other key uncertainties, we analyse recent global targets. The G8 target of a 50% cut in emissions by 2050 leaves CO2 concentrations rising rapidly, approaching 1000 ppm by 2300. The Stern Review’s proposed
25% cut in emissions by 2050, continuing to an 80% cut, does in fact approach stabilization of CO2 concentration on a policy-relevant (century) timescale, with most models projecting concentrations between 500 and 600 ppm by 2100. However concentrations continue to rise gradually. Long-term stabilization at 550 ppm CO2 requires cuts in emissions of 81 to 90% by 2300, and more beyond as a portion of the CO2 emitted persists for centuries to millennia.
Reductions of other greenhouse gases cannot compensate for the long-term effects of emitting CO2.
| Translated title of the contribution | What do recent advances in quantifying climate and carbon cycle uncertainties mean for climate policy? |
|---|---|
| Original language | English |
| Article number | 044002 |
| Journal | Environmental Research Letters |
| Volume | 3 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - 2008 |
Bibliographical note
I am writing to let you know that Environmental Research Letters (ERL) has just released the 'Best of 2008', a compilation of the best and most read articles published in ERL in 2008, as chosen by the Editorial Board, guest editors and publishing team.I am delighted to tell you that your contribution 'What do recent advances in quantifying climate and carbon cycle uncertainties mean for climate policy?' has been selected to be part of the 'Best of 2008'. A print version of the will be distributed at all conferences the journal attends this year but it is also being promoted online: the collection has been highlighted on ERL's website.
