Cooling and warming by a few degrees can happen in much less time, possibly just a few centuries - see Younger Dryas.
Which, from what I can tell, should make us more worried, since it shows how drastic and unpredictable the climate can respond to changing conditions, like greatly increasing the carbon in the atmosphere.
I mean, we just managed to do in 150 years what previously took ~100 THOUSAND years of natural activity to achieve.
Not a big deal. I don't know why people are even freaking out about it.