Africanized Killer Bees, Asteroid Impact, Global Warming, Mayan Calendars, etc. Another new one comes down the pike every 5 years, and it's always going to end the world in the next 20 years. Fortunately, they're almost always blowing the downside way out of proportion.
You're comparing apples to oranges.
The "overblown" ones you're talking about are overblown by the MEDIA.
There are basically no scientists in the relevant fields saying we need to freak out because we might get hit by an asteroid tomorrow.
It's a possibility, and we need to study it and prepare for it...but to say it's overestimated or overblown (by the people who matter) is just not true.
Global Warming on the other hand, has a huge majority of scientists in the field agreeing that we are contributing to it, and if we don't stop there are serious consequences.(note that the consequences are gradual and completely realistic).
Your comparison is flawed: you're comparing something like an asteroid strike which would be devastating and perhaps impossible to stop, but also extremely extremely unlikely, with Global Warming which is gradual and pretty well demonstrated to be occurring....it's also dishonest in claiming that those things were "overblown" (and/or the nature thereof).
Then there's the Maya thing which is just a complete joke, and the Killer Bee thing, which again was something that serious scientists brought up as a (valid) concern, but nobody was ringing huge alarm bells screaming it was the end of the world.
