1. Linacre, N. et al. State and Trends of the Carbon Market 2011 (World Bank, 2011); available at:
http://go.nature.com/xveyp4
2. Poessinouw, M. & Howard, S. Knowledge Matrix Limited Carbon Market Intelligence Report for Carbon Auditors Limited (2010).
3. Wara, M. Nature 445, 595–596 (2007).
4. Saatchi, S. S. et al. Proc. Natl Acad. Sci. USA 108, 9899–9904 (2011).
5. Levin, K. & Bradley, R. Comparability of Annex I Emission Reduction Pledges. Working Paper (World Resources Institute, 2010); available at:
http://go.nature.com/m7uipe