单项选择题

Research said to prove that greenhouse gases cause climate change has been condemned as a sham by scientists.
A UN report earlier this year said humans are to blame for global warming and there is "little doubt" it is linked to man’s use of fossil fuels. But other climate experts say there is little scientific evidence to support the theory. In fact global warming could be caused by increased solar activity.
Their argument will be outlined in a TV program called The Great Global Warming Swindle raising major questions about some of the evidence used for global warming.
Ice core samples from Antarctica have been used as proof of how warming over the centuries has been accompanied by raised CO₂ levels. But Professor Ian Clark at the University of Ottawa claims that warmer periods of the Earth’s history came around 800 years before rises in carbon dioxide levels.
The program also highlights how there was a huge surge in carbon dioxide emissions, yet global temperatures fell for four decades after 1940.
The UN report, published in February, was promoted as being backed by more than 2,000 of the world’s leading scientists. But Professor Paul Reiter said it was a "sham" given that this list included names of scientists who disagreed with its findings. He also said his name was removed from an assessment only when he threatened legal action against the panel.
"That is how they make it seem that all the top scientists are agreed," he said. "It’s not true."
Gary Calder, a former editor of New Scientist, claims clouds and solar activity are the real reason behind climate change. "The government’s chief scientific adviser Sir David King is supposed to be the representative of all that is good in British science, so it is disturbing that he and the government are ignoring a multitude of evidence against the greenhouse effect being the main driver against climate change," he said.
Philip Stott, a professor of biogeography, argues climate change is too complicated to be caused by just one factor, whether CO₂ or clouds. He said: "The system is too complex to say exactly what the effect of reducing or increasing CO₂ production would be." "It is ridiculous to see politicians arguing over whether they will allow the global temperature to rise by 2℃ or 3℃."
The documentary is likely to spark fierce criticism from the scientific establishment. Which of the following could be a proper title of this passage