How the CO2 problem can be addressed and perhaps even solved.
How about a carbon tax (or "fee" if you want to use Hansen's word) combined with a carbon dividend?
The tax/fee is collected from the fossil fuel company when it comes out of the ground. The tax/fee is based on the amount of fossilized CO2 that is produced by burning the carbon produced. About $.20/pound of CO2 is a good level after a 3 year phase-in. That would add about $4.00 to the price of a gallon of most liquid fossil fuels in addition to the amount of carbon used in refining and transportation. There would be a 6 month preparation period from the date the law was signed into law and the first collections were made and the rate would be gradually increased for the next 3 years.
The dividend would take all (less 5% for admin costs) of this tax/fee money and distribute it equally in a monthly or quarterly payment to registered participants who must be citizens of the US. Registrants must have a social security card, be permanent residents of the US, and be 18 or over. The Alaskan oil dividend does approximately this every year in that state.
What would be the result of this? People would immediately use less fossil fuels in every way possible to avoid paying the tax/fee. Those that managed to do a good job in reducing their use would actually make money from the combination. Big spenders that jet all over the planet would end up paying those that stayed at home and used less. Fossil fuels would be replaced by renewable and other sources of energy much more rapidly. A house powered by solar panels or wind wouldn't pay the tax coal or gas generated power would require. A society organized along this line would see a massive drop in fossil fuel use in a controlled fashion.