One unexpected result of climate change may to drive the formation of interesting new (or rather, old) political coalitions, specifically, green-black(shirt) coalitions that combine nativism with environmentalism. If the Germans used to call the green Party a "Watermelon Party" (i.e. green on the outside but red on the inside), we might call these new coalitions "tea leaf" coalitions. To see what I'm talking about, check out the British National Party's statement on the environment. Similar things are at work with Pauline Hanson's One Nation Party in Australia, and Pia Kjaersgaard's People's Party in Denmark. All this is to say that we shouldn't expect that the politics of climate change abatement will necessarily be "liberal" or "progressive."
(There is a strong historical precedent for such unpleasant political assemblages. Not only is there the case of German national socialism--Hitler was a famously ardent nature-lover, and the concept of Lebensraum has a certain conservationist ring to it--but let's not forget our own Madison Grant, who was both cofounder of the Save-the-Redwoods League and the author of "The Passing of the Great Race," which Stephan J. Gould described as "the most influential tract of American scientific racism," and was the academic work that did most to justify the passage of the famously racist Immigration Act of 1924, which largely shut off immigration to the U.S. for the next four decades.)
There are a couple things going on here. Part of it is about these far-right parties looking for a way to clean up their image, to go beyond the single issue of immigration and national-cultural integrity, to broaden their electoral appeal among voters already inclined to cast protest votes (i.e. green voters). But it's also important to note (and here is where the history lesson above gets valuable) that the connection between racism and nativism, on the one hand, and environmentalism, on the other, is not without a certain abiding logic.
Take the case of climate change and carbon emissions. We know that on average an American has a carbon footprint that is 7X that of, say, a Mexican. Every Mexican who comes to the United States will, very quickly, come to consume at a much higher level. Keeping foreigners out (and down) does, therefore, keep down environmental damage. Or rather, it allows the current main polluters to continue to monopolize their front-row seats at the pollution table. What underpins both environmentalism and nativism, and links the two together, is a common "zero-sum game" mentality.
What do I mean by a zero-sum game mentality? Let's break down the regional carbon emissions problem into a numerical schematic. Imagine the world consists of, on the one hand, 1000 people in the third world, each of whom produces 10 "carbon emissions units" (CEUs), and, on the other hand, 100 people in the first world, each of whom produces 100 CEUs. In this simplified model, the world as a whole is producing 20,000 CEUs. Now let's say that the world decides that we need to reduce our carbon footprint to 15,000 CEUs. Assuming there's no migration, we might work out some arrangement whereby the wealthy world magnanimously agrees to take on 80% of the CEU reduction. That would mean the third world now gets to produce 9000 CEUs, or 9 CEUs per capita, and the first world gets to produce 6000 CEUs, or 60 CEUs per capita.
But look what happens if we allow migration. (We'll assume no natural population growth, to simplify the thought experiment.) Let's say we allow just 50 people to move from the third to the first world, so that the population in the third world is now 950 and the population in the first world is 150. Assuming we agree to that same carbon reduction agreement, the per capita consumption of CEUs for current residents of the first world will have to drop not just by 40%, but by 60%! Even assuming that we agree to split the necessary carbon reduction evenly between the first and third world (e.g. to 7500 CEUs per world sector) if we've allowed those 50 immigrants to move, then first world per capita CEU consumption will have to go from 100 to 50 -- a 50% drop. In the meanwhile, the per capita drop will be only 21% in the third world. In fact, even if we make the third world take on 80% of the CEU reduction, the immigration effect will mean that per capita reduction will still have to be 47% in the first world versus only 37% in the third world.
I'm not saying that fascist policy-makers have actually done math of this sort, but you can see the logic: if there's only a certain amount of total polluting that is going to be allowed, then conserving those pollution rights for you and yours is not a politically illogical way of thinking.