Greenhouse gas emission reduction pledges made so far under the Copenhagen Accord are barely compatible with the accord’s own ambition to limit global warming to below 2°C, say scientists.
International climate negotiations are currently under way in Tianjin, China, where developed and developing nations are discussing their contributions to limiting global warming. The latest findings, published in Environmental Research Letters suggest all nations will need to up their game if temperature rises are to be kept within the 2°C limit.
Joeri Rogelj at the Potsdam Institute for Climate Impact Research and colleagues came to a similar conclusion in May (ENDS Report, May 2010). The team have now calculated the likelihood of staying within various temperature limits for this century, assuming nations achieve promises made under the accord.
Unless pledges are substantially beefed up “only low probability options remain for reaching the 2°C ambition of the Copenhagen Accord", the authors write. They add that the lack of a long-term 2050 target in the accord is a “critical deficit”.
Without a 2050 target the 2°C limit will be breached with “virtual certainty”, the paper says. Even the most optimistic interpretation of accord pledges combined with a 2050 target to halve global emissions would mean a 93% probability of exceeding 1.5°C, a target which small island states still aspire to. And there would be only a 50/50 chance of complying with a 2°C limit.