A controversial one here from Danny Hillis. He talks about changing the earth in order to reverse the damage we have done to it, by means of geoengineering.
1. Clouds help to cool the earth. And we make clouds artificially all the time, e.g. contrails made by aeroplanes at certain flying altitudes.
2. If we pump chalk into the stratosphere, we only need pump 10 teragrams yearly into the stratosphere to reverse the temperature effects caused by carbon dioxide since the industrial ages. That equates to running a hose like this all year round.
3. This is the first TED talk I watched which ended with this warning given below:
I would imagine that this would only be done if there were no other choice, where a doomsday type scenario will be about to hit us unless we do something real quick. I mean, pumping chalk into the stratosphere, surely there will be other adverse effects from the reduced sunlight, perhaps on how well our crops grow, people with respiratory issues, etc. I would advocate using a more natural way to resolve the issue rather than one which only humans can think of. After all, without humans on earth, earth would be doing really well right?
Never Stop Learning! 