In a 2003 letter to the "Financial Times", Singer wrote that "there is no convincing evidence that the global climate is actually warming." In 2006, the CBC's "Fifth Estate" named Singer as one of a small group of scientists who have created what the documentary called a stand-off that is undermining the political response to global warming. The following year he appeared on the British Channel 4 documentary "The Great Global Warming Swindle". Singer argues there is no evidence that the increases in carbon dioxide produced by humans cause global warming, and that if temperatures do rise it will be good for humankind. He told CBC: "It was warmer a thousand years ago than it is today. Vikings settled Greenland. Is that good or bad? I think it's good. They grew wine in England, in northern England. I think that's good. At least some people think so." "We are certainly putting more carbon dioxide in the atmosphere," he told "The Daily Telegraph" in 2009. "However there is no evidence that this high CO2 is making a detectable difference. It should in principle, however the atmosphere is very complicated and one cannot simply argue that just because CO2 is a greenhouse gas it causes warming." He believes that radical environmentalists are exaggerating the dangers. "The underlying effort here seems to be to use global warming as an excuse to cut down the use of energy," he said. "It's very simple: if you cut back the use of energy, then you cut back economic growth. And believe it or not, there are people in the world who believe we have gone too far in economic growth."