I was recently asked, "if a killer asteroid was approaching Earth, how much would they actually tell us?" This is my response.
They'd tell you numbers which you wouldn't understand. Then the pundits would turn those numbers into something they can scare you with, probably overblowing the threat while they do so, and Concerned Citizens would go to their Congressmen demanding answers. NASA would provide those answers.. in a completely unintelligible way, and someone would interpret those answers as dismissing the threat. Then there'd be a big argument over whether it's a threat or isn't it.
Eventually one of the egg heads with a wife will get a lecture about talking like a normal person once in a while and a press statement would be released saying exactly how likely and excessive the threat is (after it went through a few committees to ensure it was easy enough to understand, and defend). By this time the media will be completely bored with the story and the press release will be ignored by everyone, except for the next committee which is tasked with finding a solution.
Having found the solution the funding will not be forthcoming as the whole thing has already been written off as a hoax. A few years of fighting for funding and being rebuffed later, the media will pick up on the story again.. perhaps after the threat has been renamed. This time a-solution-the-authorities-have-been-ignoring will be available and someone-better-lose-his-job-over-this.
Of course, the solution that came out of that committee was for a situation that hasn't been true for years now, so we need a new committee.. this time with the President's appointment. They'll listen to a dozen different proposals, some of which have already been discarded as worthless, and choose the one that has the best political chance of being enacted quickly.
Eventually it'll get funding but the project will stall after 2 years of development, but thankfully some of the runner up concepts also got a trickle of funding. There will be a political fight to fund the more successful project over the stalled project, but that will fail, instead more money will be directed towards the hopeless project, until finally the egos on both sides subside and come up with some "compromise" solution that will half work, averting the complete extinction of human kind but still killing a few million people in a far-off-land.
Everyone will swear that next-time-we'll-be-ready but not actually do anything to ensure that's the case.. a few years later researchers will complain that their funding for early warning systems is being cut, and the general public will not care because, hey, it didn't turn out to be as big a deal as they said it was going to be anyway.