This is a major reason why forward thinking public transit investment is so crucial for the PNW.

edit I added some thoughts I see these future climate migrants as an opportunity for the PNW to start building out mass transit infrastructure that can accommodate them, this is an opportunity because the PNW is uniquely positioned in the US to pursue genuine regional mass transit infrastructure and more thoroughly erase the crimes of building this country upon the template of the car than almost anywhere else in the US.

At the end of the day the high rainfall and lushness of the region along with a proximity to a temperature moderating ocean means that we have a responsibility to make room for people who are forced to flee from places that cannot support humans as sustainably, this is just part of what being a good person is about. It will be hard, there will be plenty of growing pains but the PNW can absolutely support a LOT more people and the beauty, natural spaces and identity that people love in the PNW right now doesn't have to be violated in order to accommodate all of those people IF we invest in mass transit and allow density to develop without suffocating the region in suburban sprawl and traffic clogged stroads. It is absolutely possible to accommodate many more people in the PNW while also improving environmental protections and habitat quality, it will be hard and take many many headache inducing balancing processes but it is absolutely possible and if we do it then think of how strong we will be with that many people who love nature as much as we do all living together?

The more interesting question to me isn't whether the PNW is ready for a wave of climate migration, it is whether the rest of the US is ready for that version of the PNW that leaps ahead of the rest of the US in terms of quality of life because it took advantage of this climate migration as an opportunity rather than a burden.

The following articles a couple years old but still ..

https://www.theguardian.com/commentisfree/2021/aug/16/us-climate-change-americans-census-data

Parts of the US are getting dangerously hot. Yet Americans are moving the wrong way

The Census Bureau’s new map of the last decade’s population trends shows big growth in the west and on the coasts – and declines in the inland east coast and Great Lakes region.

Now compare that map to ProPublica maps documenting the areas most at risk of extreme heat, wildfires and flooding, and you see the problem. While there has been some recent anecdotal evidence of pragmatic climate migration, overall the census data shows America’s population growth is shifting out of areas that may be the best refuges from the most extreme effects of climate change, and into many areas that are most at risk.

Some of the examples are genuinely mind-boggling. For instance, upstate New York is considered one of the country’s most insulated regions in the climate crisis – and yet almost all of upstate New York saw population either nearly flat or declining. At the same time, there were big population increases in and around the Texas Gulf coast, which is threatened by extreme heat and coastal flooding.

I take issue with the mind boggling quip, this level of stupid is after all why we're in this mess.

They want to pretend that nothing must fundamentally change – even though we’re already seeing that everything is changing faster than ever.

Go away. We don't want any.

The new Great Migration northward in this hemisphere seems inevitable

No, it is not.

Close the borders.