Wait, what?: Article about NSF-funded research casually mentions more than 20 abrupt (in decades) warmings in the last 110,000 years where Greenland and Europe warmed 10 degrees C. and stayed "warm" for hundreds of years

1.  So why didn't any of these warmings trigger positive feedbacks so that the Earth became an uninhabitable fireball?

2.  Did these changes cause all forms of life to go extinct every few thousand years?  If not, why not?  Weren't all sorts of "delicate" things going on back then, like if the hummingbirds came back after some flower had bloomed, they went extinct?

3. Did CO2 cause all of these abrupt warmings and associated coolings?  If not, how do we know that CO2 caused any slight warming that we saw between 1976 and 1998?

The Antarctic Sun: News about Antarctica - Repeat Experiment (page 2)

An abrupt climate change is an event that occurs on a timescale measured in decades. An interstadial is a warm interlude during a glacial period that begins with an abrupt warming of about 10 degrees Celsius in Greenland and Europe that last several hundred years. There were more than 20 interstadials during the last glacial period, which lasted about 100,000 years. It ended about 10,000 years ago with the beginning of the current Holocene, a warm pause between glacial periods known as an interglacial.