At the 2009 Copenhagen Climate Summit, it was decided that by 2020, donors should rally up not less than US$100 billion per year for climate change adaptation and mitigation in developing countries. How much each donor should contribute to that annual target remains an open question, however. Dividing that ‘burden’ in equal parts would be rather unfair. Some countries are bigger and/or richer, but more importantly,some carry more responsibility for climate change than others in terms of their share in greenhouse gas emissions.