Carbon pledges and dissonant ambitions

National carbon emissions targets agreed at last year’s climate change summit in Copenhagen will lead to a global average temperature rise of up to 4.2 degrees, according to the authors of a report published this week. Owing to a lack of action to date, there is, say the researchers, only a small chance of limiting the temperature increase to the 2C set out in the Copenhagen accord.

Presenting their findings in the open-access journal Environmental Research Letters, the scientists, led by Joeri Rogelj of the Potsdam Institute for Climate Impact Research, say that even if nation states were to agree a 50% reduction in emissions by 2050, there would still be a less than 50% chance of limiting anthropogenic global warming to 2C.

Others might say that this is academic, as for practical and political reasons a 50% emissions reduction is almost certainly out of the question. In that case humanity will have to get used to a much warmer world, and one with a greatly changed natural environment.

The new report is a detailed follow-up to an opinion piece published earlier this year in the journal Nature, on which I also reported.

Further reading

Rogelj et al., “Analysis of the Copenhagen Accord pledges and its global impacts – a snapshot of dissonant ambitions”, Env. Res. Lett. 5, 034013 (2010)

Rogelj et al., “Copenhagen pledges are paltry”, Nature 464, 1126 (2010)