 Twenty years ago, the UN framework convention on climate change gave as its objective achieving a safe and stable greenhouse gas concentration in the atmosphere, and in 2004 the UNFCCC executive stated that that requires contraction and convergence of per capita greenhouse gas emissions internationally. The lack of success so far relates largely to the blame-based politics generated by some of the green organisations mentioned by Damian Carrington, who have, sadly, lacked focus and punch. The US has, in effect, walked out because of the divisive model on offer. Progress is still hostage to this unresolved row.  The UK government attempted to break this deadlock at Copenhagen in 2009 with convergence to one tonne per person per annum by 2050. This was rejected by China, which emphasised the difference between actual emissions and tradable entitlements to emit. In reality this is the only substantive issue still to be negotiated.  aubrey Meyer  Global Commons Institute