It doesn't have to end all life on earth, it just has to end ours. Moss and bacteria will survive a lot more than we will. Plus, to be rational, you have to ev

It doesn't have to end all life on earth, it just has to end ours. Moss and bacteria will survive a lot more than we will. Plus, to be rational, you have to evaluate not only probability but also potential losses, and multiply the two. A messed-up climate causing crop failures and population reverting to, say, middle ages counts would cost, say, 100 years' worth of 95% of current world GDP. Human extinction, from a human point of view, has infinite cost.