Comparability of effort by Annex I Parties is a complex and contentious
element within the Copenhagen negotiations that goes to the heart of
any agreement on emission reduction targets. But assessing
comparability in a precise and surgical manner is not possible. Simply
put, there are too many ways, both quantitative and qualitative, in
which countries efforts can be compared.

Our approach looks at emissions as defined in a Kyoto gas basket, and treats targets as responsibility targets, potentially allowing for flexibility in domestic land use, land use change and forestry (LULUCF), and international trading. This can require some translation of country pledges. Public finance for mitigation in developing countries that does not produce offsets is another element of effort that must be recognised in an overall package.

We analyse, in detail, indicators in two main categories:
(1) indirect indicators centred around emissions, population and GDP that have been the standard set used in addressing political equity concerns (including historical responsibility, CBDR and comparable effort); and
(2) trajectory indicators that focus on the consistency of national 2020 targets that include long term commitments to deep mid-century reductions, and on consistency between countries of implied inter-generational burdens.