The fact that some people consume less doesn't matter. This is a game theory situation. If one set of people reduces, another can increase.

The OP was right. We need to make using less profitable. A carbon tax would be perfect for that, and we could reduce the income tax to offset. We get less of what we tax, so we'd have more income and less carbon.

I actually think international efforts should be focussed on getting countried to agree to swap existing taxes for carbon taxes.