The Group of Eight industrialised countries have agreed to more stringent cuts in greenhouse gas emissions than ever before but big developing economies are unlikely on Thursday to join them in doing so.

The G8 leaders pledged at their summit in Italy on Wednesday to take on the lion’s share of the emissions reductions that scientists say are needed to tackle climate change, with cuts of 80 per cent by 2050 for developed countries. This would contribute to a hoped-for target of halving emissions globally by the same date.