The decision by the US government to classify greenhouse gases as a danger to human health has been hailed by environmentalists.The ruling now means carbon cuts could be ordered without the the approval of Congress. It comes off the back of last week’s White House pledge to slice its CO2 emissions by 17 percent by 2020, on levels measured in 2005. However, activists attending the Copenhagen climate talks are hopeful the latest move will prompt deeper carbon cuts. Director of Climate Politics for Greenpeace Martin Kaiser said: ‘‘After the EPA announcement to get active against CO2 emissions, President Obama is now able to reduce CO2 levels in America to reach the required targets to tackle global warming. In Copenhagen, we expect President Obama to raise emission targets and with this an historic deal can be reached.’‘ With latest temperature measurements showing the last decade has been the warmest since records began, activists are urging President Obama to push through climate legislation. Louis Leonard from the World Wildlife Fund said: ‘‘It’s a piece of the puzzle… but it’s not the whole solution. The whole solution you get through passage of climate regulation and that’s why we want the president when he comes to Copenhagen to explain to the world that he’s going to make passage of climate legislation his top priority.’‘ Switching from carbon, to more sustainable ways of generating electricity remains a major headache for Obama. But, many believe the latest ruling by the US will boost talks in Copenhagen.