The _state_ isn't alarming, it's the rate of change. The transition is happening on a scale of human lifetimes instead of geological time.
replyYeah. The XKCD "Timeline of Earth's Average Temperature" is, I'm pretty certain, the most frightening chart I have ever seen.
replyPrecisely. Humans can adapt to almost anything but we can not do it fast enough with 8 billion+ people.
reply> Earth has been in a greenhouse state for about 85% of its history.
replyAnd during those periods there were no human beings. And no agriculture, or unstable globalised economiies, or dense urban societies vulnerable to disruption.
It is, of course, interesting that our planet has this long, varied existence that pre-dates us. But it is of little use in understanding how to get us out of the hole we're in. And it is arguably dangerous, because it misleads people into thinking that we have the capacity to adapt to such conditions, when we manifestly don't.
To put a different shade on the meaning, this climate period is rare, easily disturbed, and difficult to restore even with vastly more powerful technology.
replyThe more common greenhouse state is unlikely to lead to a Venus runaway, but it will be hostile to us.
We might very well require the rare climate, and perish in the common.