Whenever economic conditions change, there are obvious primary effects and less obvious secondary effects. Rising oil prices have the primary effect of causing people to spend more on gas. Secondary effects include reduced oil use, reduced demand for gas-guzzlers, higher food prices, and increased research into alternative energies.
Asako Ohinata at the University of Warwick did a study of the effect of a working families tax credit on fertility in the UK. The question was whether people would actually have more children if given a modest economic incentive.
The results were mixed. The tax credit did not affect when couples had their first child. But, among couples who had one child, they had a second child sooner as a result of the tax credit.
This speaks to the amazing power of economic incentives. If you want to reduce dependence on foreign oil, then increase gasoline taxes. If you want to reduce garbage output, then tax items at the time of purchase based on the amount of garbage they will ultimately produce. There may be political barriers to such actions, but there is little question that they will work.