Problem is we have about 50% certainty...
And you say it is unacceptable for them to advocate doing anything?
http://neo.jpl.nasa.gov/risks/a410777.html
Current impact risks overview is here. 50% chance of a large object would certainly be unprecedented.
http://arxiv.org/pdf/0804.1126.pdf
Now, replace the comet watchers with paleoclimate researchers finding out what happened when the planet last time crossed 450 PPM (the other way around).
a) suddenly out of the blue, a Ford Transit mutates into a toaster.
b) someone is "pretty sure it is related to the impending comet impact".
c) Everyone goes YAY SCIENCE!!!
Sorry but derision is the only thing left. It's not science, it's religion.
a) suddenly out of the blue someone delivers a load of fish.
b) Some guy doesn't notice this and goes "pretty fucking sweet; I'm totally wasted on mushrooms and I reckon that bearded dude over there turned that loaf of bread into all those fish. Damn I've got the munchies."
c) HE'S THE FUCKING MESSIAH.
There is no causality chain established other than a hunch.
I do agree that some things are perhaps too easily reported or assumed to be caused by climate change when there is not much evidence to support that (yet).
If we do spend the time, money, and effort to do things like reduce emissions, will we be worse off than we were? Would it not make more sense to use renewable energy resources, and save up the 'easy' sources of energy (oil, coal, etc) for other applications?
But blaming everything on climate suddenly isn't the right answer. Perhaps someone lost a ship load of PCP in the sea and they just snuffed it. And they're trying to hide that.
Another hypothesis that could be tested rather than "fuck blame it on climate so we can get some funding and get some nice new Herman Miller chairs and a new MacBook each"