Global Warming

Richard Muller writes a persuasive editorial in Sunday's NY Times, claiming that his studies show a powerful correlation between the increase in carbon dioxide and the rise in temperatures over the last 250 years, a crucial link in showing global warming is caused by man's activity.  By his account, he had controlled for other factors, e.g. sun-spot activity.  Two comments about this: 1) he's simply describing his conclusions.  But he's published his work, so others can find flaws in his reasoning if there are any.  And that's the way science should work;  2)  as a good scientist he doesn't confuse correlation with cause.  But  if his correlation is strong, then, as he rightly points out, any competing theory must account for this correlation.