There have probably been over 100 studies in the past 20 years that have compiled conclusive evidence that climate change happens very quickly. There was resistance to the idea for a long time because it was so radically different from the uniformitarian model, but under the weight of well-tested evidence, the consensus has changed.
The climate
will keep warming for a few more years. There is always a dramatic warm-up before the return of active ice-age climate -- it seems to be an integral part of the process. The neocons are cynically exploiting this finding right now to fight against better, more enlightened environmental regulation. And of course, they don't care about advance planning for any climate change. It might interfere with their ideology or the value of their protfolios.
The world climate system is now known to be "bi-stable". When climatic forces build up (as they do in a cyclic fashion) to a certain point, the world's climate changes rapidly and goes into the other state. This conforms to a well-known systems analysis model known as
mathematical catastrophism theory.
As for the asteroid or comet strike, they have happened many times, and only the very largest strikes have triggered long-term ice ages. The process is very "deep", and probably involves hundreds of periodic variables in both climate and cosmology.
It is very easy to find this theory dubious. I myself didn't think it was possible until I read through some of the literature. Nearly everything we're finding now from improved ice-core analysis indicates that the next glaciation will happen quickly. It will take a long time for the ice sheets to become as
thick as they were 24,000 years ago, but the actual climate
change will hit fast.
By the way, the average air temperature of the world during an ice age may only be 5 or 10 F lower than it is now. An ice age is a climatic
system, not just the presence of more ice and longer winters. The weather during active ice ages is more dry than cold.
If you are interested in following the research for yourself, here's a link to get started:
http://www.whoi.edu/institutes/occi/currenttopics/ct_abruptclimate.htmIt is easy enough for the raw beginner to understand, but comprehensive enough to give that same beginner a solid background in abrupt climate change findings. It's from a group of oceanographers at Woods Hole Oceanographic Institute. They also list many scientific references in different places. It will at least get you started with the climatology and oceanography terminology so you can use search engines like Google.com to look for more.
--bkl