It is well known that many strategies for reducing greenhouse gas emissions also decrease emissions of health-damaging air pollutants and precursor species, including particulate matter, nitrogen oxides, and sulfur dioxide. In a survey of previous studies we found a range of estimates for the air quality co-benefits of climate change mitigation of $2- 196/tCO2 with a mean of $49/tCO2, and the highest co-benefits found in developing countries.
By comparison, an effective carbon tax that would bring our emissions down very sharply (>80% reduction) is estimated at between $75 and $300 per ton. What this study suggests is that apart from any need to mitigate climate change, the benefits to human health alone suggests we ought to be taxing carbon emissions at around half that rate purely to reflect the real cost to the health of society from the crap the fossil fuel economy spews into the air.
Current CO2 emissions world-wide at presently around 28 billion tons a year. Suppose we could reduce that to 3 billion. The cost savings in reduced disease burden would be in the range of about $750 billion to $2 trillion dollars per year. Right on the mean ($50 per ton) we would save 1.25 trillions dollars per year, which is greater than the total cost estimate for reducing our CO2 emissions.
It's often been said that if the deniers are wrong, and we do not act, the result will be a catastrophe, while if the scientists are wrong, and we do act, the worst that will happen is a world with cleaner air, more efficient industries, and less dependence on fossil fuels. This study shows illustrates that point with hard numbers that show that even taking only one aspect -- cleaner air -- of the secondary benefits of discourage the burning of fossil fuels dwarf the cost of transitioning to greater efficiency and other energy supplies.