Forty six and cloudy, that's the forecast for Copenhagen, Denmark as a Climate Summit brings in 15,000 world leaders and environmentalists. One big subject, no surprise, climate change. You may know from science class that the earth goes through warming and cooling periods. The last cooling one between the 1940s and the 1970s. Scientists say it's been getting steadily warmer since then. But there is major disagreement about whether people have anything to do with it. Many leaders in Copenhagen don't wanna get hung up on that. They are trying to reach an international climate deal. It could limit greenhouse gases which many scientists blame for climate change. And in fact how much we pay in gas and electric bills. But one reason why an agreement could be hard to get. Recent accusations that scientists at a top research lab haven't told the whole truth about climate change.