You know, this was the conservative view taken by a number of climate researchers back in the 1960-70's. They did however lose out to the group going: "Hm, but we do think we have something to worry about here, and IF we have, it's going to be a very weak defense when the feces hit the fan, that we saw this looming, but said nothing until we were sure." There is an actual dilemma here for them. Wait until it's obvious, but don't give people a heads up in advance, or get themselves out there now, and risk being accused of fear-mongering. It about how to manage risks. But now the climate researchers have said their piece. (Though they did think they might actually be believed pf course.) So now it is actually a matter of politics, and of course we have the option of dismissing the science we have so far. But that's politics, and not science. And it's the way it was supposed to work anyway; science supposedly provides an unproblematic basis in the form of facts, and politicians then decide policy. Except in this instance enough of the scientists thought it too potentially risky to wait for confirmation.