Pick your favorite global catastrophe, or global extinction level event:

Asteroid/Comet impact,
Yellowstone/Other super volcano,
Numerous, coordinated global volcanic eruptions,
Gulf stream change,
Mega solar flares,
Sun turning off???,
Massive, deep sea, methane release,
Earhquake/impact tsunami,
Massive earthquake: continent division,
Global/continental virus/infection,
Pole flip
...

If you research any one of these topics, you will find numerous scientists (and doomsdayers) who testify that the event is well over-due. The only thing that has changed over the past couple million years is the introduction of us filthy humans.

Is it possible that their dating system is flawed, or has something changed about the planet to make it less vulnerable.

Are we are so facinated by the thought of disaster that we keep searching, hoping to find one.

Or, are the claims meant to keep the human race in fear for control purposes.

I really hope for humanity sake that one of those things you listed is what kills us. How embarassing would it be if we killed eachother off! Imagine the Aliens response when the find us:

Yea.... but anyways, Is it possible that..... heck I'm to tired to think!

You may find some scientists who say they are long over due or won't happen but u'll also find scientists who through their own research believe it is coming.

Climate change is real, i'm in Britain and the weather is weirder than usual, its more like sub tropical some days.

Im not qualified researcher so i wouldn't know about the details of the gulf stream and the other catatrospheres you've mentioned but im sure they all have a decree of probability of occuring. Your post was a bit too generalised and unsubstaniated for my liking.