Campaigners have been warning the G8 of catastrophic consequences if they fail to act on climate change.Yesterday China and India blocked efforts by some nations to sign up to a target of halving world greenhouse gas emissions by 2050. There is agreement that world temperature rises need to be limited to two degrees celsius, but many say that is not enough. European Commission President Jose Manuel Barroso said: “A key part of the solution wil be financing, fighting against climate change. We will come forward with proposals in good time on financing and we are ready to play our full part. As the largest contributors to past emissions, developed countries have a special responsibility to take the lead, but this is not going to be enough. Emerging economies, for example, where gross emissions is surging, must also join in the effort.” Greepeace and other environmental groups said they would be very disappointed if the final result of the G8 was a failure to set a target for halving greenhouse gas emissions.