A 350 ppm Emergency Pathway

A Greenhouse Development Rights brief

Author(s): Baer, P. ; Kartha, S. ; Athanasiou, T.
Year: 2009

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, 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 is needed if we are 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 2 degrees C temperature target, and to other, supposedly 2 degrees C-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.

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