The three biggest threats to mankind are nuclear exchange, biological/pandemic and global warming. To ignore any one of them is stupid. Of course you would ignore one of them.
Actually according to CIA reports from the 1970s, the three biggest threats to mankind are nuclear exchange, biological/pandemic and global COOLING. Except that it should be noted that global cooling is natural and not caused by man. We need to use our inventiveness and resources to adapt to a cooling earth as we likely enter another mini-ice age.