Their points claims that Krugman greatly underestimated the price increase impact of a tax on CO2, when he did no such thing.

The studies he quotes may be wrong, but if there are externalities gains that are greater than tax * consumption, then the net result is a gain. That the price impact would be spread over everything we use rather than a single item makes no difference to its macroeconomic value. I think they are doing double counting without realising it.

Earth provides enough to satisfy every man's need, but not every man's greed. Gandhi