Sure, the rise of CO2 in the atmosphere is fine for life in general, but I don't really have a huge emotional attachment to the shallow-sea fish that will have all that lovely extra living space right where Miami used to be. The future Earth will not be dystopic for biodiversity, but it will make things more difficult for us, and that is, ultimately, what I care the most about.
I get that argument. Sure, it may be bad for certain ecosystems we currently rely on, or for the current configuration of human civilization. But the article we're discussing mentions the next 4 galactic orbits. No one will give a toss about Miami in 100 million years. I will be surprised if it is relevant in 10,000.
Do you have any convincing arguments for why a wetter, warmer, carbon-rich world would be a downside for humans on that scale? If I were betting on us surviving, I'd take that over an ice-age any day of the week.
Land, and especially coast, which is a lot of the areas most suitable for human habitation. Earth's surface is already 70% water; the ideal is probably 50%, so we should be looking to lower the water level rather than raise it.
Parasites and diseases, much more common in warmer, wetter places. You'll notice that on the whole tropical civilizations have been less successful than those in colder climes; there's a wide variety of possible reasons for that, but the effects of parasite load on health and general intelligence are real. Our technology/economy/etc. has so far been much better at helping us live in inhospitable cold places (Norway) than at dealing with tropical parasites and diseases.
Not to mention that a climatic shift on this timescale, in either direction, has historically meant about 20% of extant species going extinct. How lucky do you feel?
