person does will affect more than one or two generations in the future. This is a huge motivator for much of human actions and morality, even if often left unsaid. A world without this is almost inconceivable, and its why the topic has been explored by sci-fi writers. The second big impact is the shortened lives of children born recently or in the near future. One mild criticism is that the time frame that Guy has laid out is within twenty years (and his framework is much shorter than most of the doomsday predictions). This is a fairly substantial chunk of time to live out your lives, and much of it will be living out your lives surrounded by people who think that things will keep chugging along somehow as before. Incidentally, I think the weak point in Guy's argument is the positive feedback mechanisms. The world has never been in this situation in terms of climate fluctuations since the ice ages, and have never been in this situation in terms of anthrogentically-affected climate fluctuations, so there is considerable uncertainty about how the positive and negative feedbacks play out. Its like being in the midst of a vast, dangerous, and fairly pointless science experiment. Now the human brain tends to convert probabilities to either 0% to 100%, but there is still room for pleasant shocks and surprises. Ed, on the way to extinction, whether in 20 years or 40 years the climate will get increasingly more erratic, there will be