But Myles Allen, a lecturer on atmospheric physics at Oxford University, said assessing a “safe level” of carbon dioxide in the atmosphere was “a bit like asking a doctor what’s a safe number of cigarettes to smoke per day”.^{[1]/a/sup/p/blockquote}

I wonder if the good professor is aware that we need at least some carbon dioxide, but we do not need any cigarettes./p

1. Mr. Richard Black. “Stark warning over climate change” BBC News 2006-01-30. http://news.bbc.co.uk/2/hi/science/nature/4660938.stm /font/li/font/ol