Responsibility for past and future emissions

Wei et al (2012) use two earth-system models, one in from US national lab NCAR and another – derived from it in part, from Beijing Normal University. First, they run scenarios for historical emissions, and find developing countries contributed 20-40%. Looking at responsibility for historical emissions , they find “ that developed countries had contributed about 60–80%, developing countries about 20–40%, to the global temperature rise, upper ocean warming,and sea-ice reduction by 2005.” Secondly, they construct scenarios of future emissions – Cancún pledges plus further action, with 50%/80% below BAU for NAI / AI, and both to zero by 2100. The results of their analysis suggest that developing countries contribute two-thirds to future reductions relative to BAU, developed countries only one-third. Apart from not always being clear that the results of the future emissions are due to pledges and the further reductions, they seem to conduct a careful analysis – as far as I can tell.

It’s published in the PNAS, the Proceedings of the [US] National Academy of Sciences, so should be carefully peer-reviewed – and certainly has an amazingly long list of authors http://www.pnas.org/content/early/2012/07/16/1203282109.full.pdf?