What percentage of the population of 20 somethings fall into the category of "mobile, non-property owning, wanders to find a job"? 1-5%? And you don't think that peripatetic workers will have to deal with the political and societal implications of climate change? What will the impacts be when California and Arizona decide between allocating water for urban areas or agriculture? What happens when the Columbia Plateau is too hot for sustained crop yields? Those workers can't just travel somewhere entirely removed from those realities.
Even ignoring the absurd reduction to a small proportion of 20 somethings, the original comment was about 20 somethings in general, not just a hypothetocal mobile workforce. The majority of 20 somethings will not be able to load up their $40k sprinter van and head for greener pastures.
I disagree. I live in the western U.S. and climate change is already a real and present part of life here. Wildfires are a more prevalent threat due to many factors, and climate change is a leading driver. Consistent drought is challenging water rights and allocation - most notably with with Colorado River Compact. More common heat waves threaten agriculture stability in the Southwest, Pacific Northwest, and Great Plains. These are all things that are happening now, and are projected to get worse.
On a more country wide scale, we can expect foreign migration to the U.S. to increase. Sure, some folks can migrate inwards from the coastal U.S., but what will people in coastal El Salvador or Guatemala do?
Even ignoring the absurd reduction to a small proportion of 20 somethings, the original comment was about 20 somethings in general, not just a hypothetocal mobile workforce. The majority of 20 somethings will not be able to load up their $40k sprinter van and head for greener pastures.