Second, although the cost of energy would rise, the rise would be much more modest than you seem to believe. I posted a graph upthread showing that non-fossil alternatives are already comparable to coal on price. What's needed is an incentive to switch, and the tax provides that.
Third, you're only looking at half of the cost equation. The cost of doing nothing on climate change is roughly five times higher than the cost of mitigation (Stern 2006), and the cost of doing nothing falls disproportionately on the poor. So if you were really concerned for the poor (are you?) then you'd be clamoring for a system like this one.
Fourth, not only is your position uneconomic, it's immoral. Why should innocent third parties continue to bear the external costs of fossil carbon use? Taxing fossil carbon is one way to recover those costs, as well as being a good way to reduce them.