What are some global warming facts that shocking or disturbing?
Probably the concept of tipping points and irreversible change would be the most disturbing to me.
Most people think that climate change might be gradual giving us lots of time to adapt. But this is not necessarily so. Some times an Earth system component can go along and change in a slow linear fashion, but then reach a tipping point where further changes happens very fast. For example, geologist know that past global warming events can accelerate suddenly when feedback loops start to amplify the rate of warming - in other words, the system reaches a tipping point and starts to flip into a much warmer world much more rapidly.
The other concept of irreversible change is also worrisome. This means that once a system component starts to tip into another state, there may not be a way to reverse this momentum for thousands or tens of thousands of years. Scientists feel that melting ice in Greenland and Antarctica may be an example of this irreversibility - if the ice really starts to melt, there may be no way to stop it even if we shut off all greenhouse gases at some point in the future. This would mean that many coastal cities would be doomed and there would be little we could do about it.