Even if we could all agree on the facts of climate change, there's plenty of disagreement on how to handle the effects.
Should we stop trying to farm in semi-arid country? Should we pull all housing back from the edge of the oceans and the forests? Some of that will have to happen, and it will result in people moving away from climate-impacted places.
The numbers of climate-displaced people grow into the billions, says science journalist Gaia Vince. She fills out the picture in the book Nomad Century: How Climate Migration Will Reshape Our World.
The author tells the story of what's happened already, and what is likely to come.