1/21    Amount of carbon tax per ton of CO2 required to limit global warming
        to 2 degree Celcius if we:
        - start in 2013: $30
        - start in 2020: $100
        - start in 2030: $infinity
        http://www.csua.org/u/z0a
        \_ Why should I care? I will be dead long before this is a real problem.