I'm really looking forward to the next book in the series, though I fear he may have to introduce a technological deus ex machina to let the human race go on in even marginal comfort.

He already has introduced it. That algae/lichen symbiote that increases lignin production in trees 40-fold (or some such number). It'd turn the trees into super carbon-sponges. It's been mentioned. I don't know if it's ready for full application yet, though. Probably needs some work by those genetic engineers in California. :-)