"If we accept that, say, 2 billion people, will be killed by the direct effects of AGW in the next 150 years (figures plucked from the air, but not out of question),"

If you accept that as being "not out of the question", it's only because you've become a credulous and stupified individual unable to separate fiction from reality. Let's say, as a much more reasonable alternative, that putting the breaks on development, particularly in the 3rd world and elsewhere, will kill an order of magnitude more people, through poverty and disease, than any almost imperceptible increasing in atmosphere surface temperature.