Evaluate each of the following proposals to raise money to address global warming. Consider for each the equity issues, whether the proposal will work, and the efficiency in terms of minimizing transactions costs.

a. An advertising campaign urging everyone to walk and bicycle to work instead of driving.

b. Impose a tax on carbon (a component in gasoline, heating oil, and coal).

c. Raise the income tax and dedicate the money to subsidizing solar and wind power and home conservation.

d. Impose an international tax on all activities that produce atmospheric carbon dioxide and use the revenue to pay people in low-lying countries to relocate when the ocean levels rise.