Somebody: We should be able to oppose capitalism without buying into the immiseration thesis. We no longer accept (or most of us do not anyway) that private ownership of the means of production means that living standards in the West need to perpetually head downwards. Gradually, maybe even kicking and screaming, we will have to come to accept that this holds true not just for the West but for most of the rest as well.
So, yes a horrific percentage of the world subsists on $2 a day - about 2.6 billion people. That's roughly 40% of the world's population. It's a figure of genocidal proportions. But then, as recently as thirty years ago in 1981, it was more like 68% of the world living under $2.
So, in other words, during the neoliberal period in which the world's working classes have come under sustained assault, the development of the productive capacities of the nations of the world *despite* not because of this reactionary political shift, has meant that an enormous drop in the proportion of the world living under $2 has occurred. And then we consider - 2100 is not 30 years from now. It's three times that. What proportion of the world will live under $2 a day by then? Even if we assume a neoliberal capitalist century - which I refuse to concede, but will for the sake of argument - I submit that trends suggest that a very small percentage of the world will be living under such conditions of absolute poverty indeed. Which means that the world will be much richer even under the pessimistic assumption that the dire political and economic trends of the last generation will perpetuate themselves for the next 90 years.
Now much of this decline in the proportion of the world living in extreme poverty occurred in China. But this only tells me that we want more of the developing world to look more like China, not in terms of authoritarianism or lack of worker's rights, but with reference to industrialization. If the left cares more about people and less about inanimate rocks and unsentient trees and about maintaining an ecological status quo no matter the costs, it will have to support development in the global South, even if this means an increase in CO2 emissions - because paradoxically it is precisely that wealth which will allow nations to cope with climate change and ameliorate further temperature increases through fiscal policies, development of new energy technologies, and redistribution of wealth and not through demographic disasters.