Catastrophy and environmental decision making

"To my knowledge, research to date does not give us the answer. Those studies cited above that ignore possible catastrophic impacts provide some evidence that we should move slowly. Those studies that do consider the possibility of catastrophic impacts suggest a more stringent emissions policy, but the catastrophic impacts in these studies are more or less assumed, rather than inferred from empirical evidence."

From "Uncertainty in Environmental Economics" by Pindyck.