The True Price of CO2: What Experts Say

Estimating how much a ton of CO2 costs society, called the social cost of carbon (SCC), is tough. It needs to consider the whole climate and economic system, and how changes spread in time and space. Scientists have looked at the models used to calculate SCC but in bits and pieces. No one has put it all together. So, researchers combined 1, 823 SCC estimates from 147 studies and asked the experts. Turns out, the 2020 estimates vary wildly, showing a skew to the right.

Key factors like long-lasting damages, how Earth's systems are represented, and how costs are valued play big roles. Yet, experts think the current SCC is too low because models miss some structural elements and damages, and they use high discount rates. To fix this, they trained a random forest model on all this data and created a synthetic SCC. This new value, $283 per ton of CO2 for a 2020 pulse year, is higher than most governments' estimates.

Actions