A recent arti­cle from the Uni­ver­sity of Pittsburgh’s Cen­tre for Biose­cu­rity, Reduc­ing the Risk of Human Extinc­tion.

Abstract: In this cen­tury a num­ber of events could extin­guish human­ity. The prob­a­bil­ity of these events may be very low, but the expected value of pre­vent­ing them could be high, as it rep­re­sents the value of all future human lives. We review the chal­lenges to study­ing human extinc­tion risks and, by way of exam­ple, esti­mate the cost effec­tive­ness of pre­vent­ing extinction-level aster­oid impacts.

via Schneier