Hey, sudden flash of genius!!
Let's propose to the global warming crowd to transfer megatons of CO2 from Venus to Mars to test the theory that CO2 will act as a strong greenhouse gas. That way we can get an interplanetary transport infrastructure built and operating with a vocal and influential crowd supporting it. It would take decades to get it built and centuries to finish the job, but in the end we might get a more reasonably habitable world out of the deal - Mars that is. Venus is a hopeless case.