It's not longer possible to deny that climate change is occurring -- too much science confirms it; too many people understand the reality. Thus, politicians and special interests who have denied climate change are in an awkward position: how can they spin their longstanding refusal to act? How can they maintain their personal or political bias against action, in the face of so much irrefutable data? Their newest, most disingenous tactic is to pretend that it is unclear whether human activity causes climate change, or whether climate change may be "natural." They hope that by manufacturing doubt, and demanding "more study," they may be able to ignore the risk and the responsibility for a few more years. From Science (Vol. 306. no. 5702, p. 1686, published in December, 2004), this analysis of the literature clarifies that their latest tactic is just another deception. The data is already in; scientists have no doubt that human activity is influencing the Earth's climate.