In the interim it could be quite disruptive for humans (flooding, extreme heat in once livable places, etc.) but on the whole warming has typically been very good for life.
Global cooling would be catastrophic.
Global cooling would be catastrophic.
The Great Barrier Reef is now thought to be doomed to coral bleaching in the next few decades. Half has been lost already.
Another example is that biomes are moving at rates ten times faster than we'd expect from natural climate change. That is it say, plants and animals and fungi need to move ten times faster uphill or toward the poles to keep up. This is being documented in mountainous rainforests, but the sheer number of species in those areas is so high, and their natural ranges so small, that some are no doubt being lost before they can be discovered.
Even if all those species could keep up with the pace of change (and they can't), the unlucky ones will find themselves with nowhere to go. Some climates won't move, they'll disappear. Even if a suitable climate opens up somewhere else on earth, species are not known for teleporting.
It's not recommendable to wait for the warnings "to materialize" because the game will already be lost.