Dick Cheney is reported to have conducted the "War on Terror" by this standard: even if there's just a one percent chance of a terrorist attack coming, act as if it is a certainty.
We're facing a worse longer term threat than any terrorist attack: the possibility that global warming will change the planet's climate so much that our descendants will face food shortages and mass starvation, water shortages, unbearable temperatures, and fierce struggles over the planet's dwindling resources.
I would apply Cheney's standard to that possibility: even if there's just a one percent chance of such a miserable future for those who follow us, act as if it is a certainty. We should start a crash program to reduce carbon emissions now.
(Brad Plumer reports on how fast CO2 concentrations are rising, and the narrowing window we have left.
Joe Romm rounds up the dire predictions.)