Looking at natural experiments

“Earth's climate cannot be replicated in a lab. So to understand how this critical component of the planet's heat regulation works, scientists must rely on "natural experiments." David Biello, Scientific American, January 6th. “A team of American and French scientists has developed a method to determine the influence of past volcanic eruptions on climate and the chemistry of the upper atmosphere, and significantly reduce uncertainty in models of future climate change. In the January 5 issue of the journal Science, …” SpaceRef.com