World leaders haven't been able to come up with a big agreement at the Copenhagen climate change summit.
Instead America agreed to work towards limiting temperature rises to just two degrees along with China, India, Brazil and South Africa.
For two weeks officials from 192 nations have been meeting in Denmark to try to come up with a deal.
Green campaigners say they're unhappy leaders didn't work harder to set tough legal limits on pollution levels.
Many people had hoped that countries would agree to reducing the amount of greenhouse gases that countries can produce.
Lots of leaders have said they see this meeting as just the start of the work that needs to be done to tackle climate change.
Prime Minister Gordon Brown said: "I am now going to lead a campaign around the world with other countries for the legally binding treaty that is the obvious next stage from this. "