Lots of clouds this week. The peculiar picture above shows the eruption of mount Pinatubo in 1991, which apparently resulted in a certain amount of global cooling (next to some serious negative effects). If a vulcano can do that, why not humans?
Environmental scientist David Keith talks about a cheap, effective, shocking solution to climate change (TED video): What if we injected a huge cloud of ash into the atmosphere, to deflect sunlight and heat? As an emergency measure to slow a melting ice cap, it could work. Keith discusses why it's a good idea, why it's a terrible one -- and who, despite the cost, might be tempted to use it.