Social cost of carbon estimates have increased over time

Estimates of the social cost of carbon are the yardstick for climate policy targets. However, there is great uncertainty and we do not know how estimates have evolved over time. Here I present a meta-analysis of published estimates showing that the social cost of carbon has increased as knowledge about climate change accumulates. Correcting for inflation and emission year and controlling for the discount rate, kernel density decomposition reveals a non-stationary distribution. In the past 10 years, estimates of the social cost of carbon have increased from US$9 per tCO₂ to US$40 per tCO₂ for a high discount rate and from US$122 per tCO₂ to US$525 per tCO₂ for a low discount rate. This trend is statistically significant if sensitivity analyses are discounted and paper quality weighted. Actual carbon prices are below its estimated value almost everywhere and should therefore go up.