@Blackrobe They will just have to move north. Global warming or not, it's not that hot up here. Turtles might be slow, but they are faster than any climate change.
@Kaarme
That is if the turtles have such adaptation in the first place. Most of them go back to the same beaches every time. Current climate change trend is faster than biological adaptation.
Also, coral reefs are dying due to increasing temperatures. I think you could imagine how this would affect everything up the food chain.
@jonsmth I wouldn't worry about that. Turtles are ancient creatures. The climate of Earth has always been changing, up and down. Sometimes there has been a kilometer of ice on top of where I live, sometimes this place was far warmer and luxurious, like a much southern area. Though the changes might seem the greatest in the far north, it also meant the Middle East, for example, which is now mainly forbidding sand desert, was sometimes full of lush grasslands, which, in turn, made it possible for agriculture to be born. Turtles and tortoises have lived through all of these changes and periods. They even surived the bloody meteor strike and the ensuing nuclear winter that finished off the dinosaur overlords.
If anything kills 'em all, it's going to be humans through more direct methods than changing the climate a little bit. Though of course if they are first weakened by the climate change, they will become extinct far easier for other reasons.
@Kaarme
Yes, but those changes were gradual - like tens of thousands of years gradual.
There are always some animals that have survived a mass extinction event, but that doesn't guarantee that the descendants of those survivors could survive the next one especially when the conditions are different, and they have since adapted and specialized to the newer climate and environment.
Projected/estimated increase of average global temperatures now are much more severe, like what would have taken a thousand years now would be like a few decades.
This is what I mean by climate change being faster than biological adaptation.
Here's an easy to understand graph you could start with https://xkcd.com/1732/
I won't claim it's definitive proof (It's a humor website, but the content is written scientists), but I hope our casual exchange make you think twice about your opinion on it (and maybe read some papers).