Yes, but it's healthy scepticism. Environmentalists are healthy sceptics. We've learned to be healthy sceptics. Often I think the human race is a little too arrogant when it develops new technologies. We introduce them first and then try to patch up the damage later. What we're trying to say here is to be very careful because once the genie is out of the bottle, you can't get it back in again.
On October 27th, 2016. See this statement in context.