The Greenhouse Development Rights project, of which we are core members, has just released a brief report (only 12 pages) entitled A 350 ppm Emergency Pathway. In it, for the first time, a very precise and up-to-date representative 350 ppm pathway is developed. Like so:
The first phase of the 350 campaign has been a wild success. 350 is now an international symbol of emergency climate stabilization. More importantly, the 350 target reflects a scientifically-grounded assessment of what global climate protection really means. But what would it actually take to bring the atmospheric carbon-dioxide (CO2) concentration back to 350 parts per million? This memo provides a quick, up-to-date overview of the issues here, which are significant to any plausible emergency emissions-reduction effort. It focuses on the extremely limited size of the global CO2 budget that would remain to us in a 350 ppm future, and on the shape of the emissions pathway that’s needed if were to keep within that budget. In particular, it specifies a representative emissions pathway consistent with a 350 ppm concentration target. By way of context, it then compares this 350 pathway to an emission pathway consistent with a 2C temperature target, and to other, supposedly 2C-compliant pathways that have significantly lower odds of actually satisfying their target. Finally, it offers a brief glimpse of the challenges that all true emergency climate-reduction targets raise in this North / South divided world.