Earlier quoted context omitted.
Among the many effects of climate change, 700 million people live in areas that will become almost uninhabitable due to rising sea level and flooding at current emission rates. Do you seriously think that people adapting by speaking a different language is as bad as that?
Yes, on my list the latter is a more serious problem than the first, it is more certain to be happening, and its effects are more permanent.
Do you doubt that climate change will displace 100s of millions and destroy many large and distinct cultures (e.g. island states) at current emission rates?