Social Cost of Carbon Calculator

The Social Cost of Carbon is a dollar estimate of the economic harm caused by emitting one additional metric ton of carbon dioxide into the atmosphere. It accounts for future damages from climate change — including impacts on agriculture, health, sea level rise, and extreme weather — discounted back to present value. It is widely used in cost-benefit analyses of climate and energy regulations.

The EPA's 2023 estimates are the most current federal figures, developed using updated climate and economic modeling at discount rates of 1.5%, 2%, and 2.5%, with 2% as the central estimate. The IWG (Interagency Working Group) 2021 interim estimates were the previous federal standard, available at 2.5%, 3%, and 5% discount rates, with 3% as the central estimate. EPA values are generally higher, reflecting improved damage modeling.

The discount rate determines how much weight is given to damages that occur in the future versus today. A lower discount rate (e.g., 1.5–2%) gives more weight to long-run climate damages, producing a higher social cost. A higher rate (e.g., 5%) heavily discounts future harms, resulting in a much lower social cost. The choice of discount rate is one of the most consequential — and debated — assumptions in SCC estimation.

Non-CO₂ greenhouse gases like methane and nitrous oxide are converted to CO₂ equivalents using Global Warming Potential (GWP) factors. Methane has a GWP of about 27–30 over 100 years, nitrous oxide around 273, and HFCs in the hundreds to thousands. The social cost is then applied to this CO₂-equivalent tonnage, reflecting each gas's relative climate impact.

The analysis year is when the policy decision is being made — it sets the baseline for discounting. The emissions year is when the actual greenhouse gas is released into the atmosphere, which affects the magnitude of damages because emissions occurring later may have different marginal impacts. In many standard analyses, these two years are the same.

Governments and regulatory agencies use the SCC to monetize the climate benefits of reducing emissions in regulatory impact analyses. For example, when evaluating fuel economy standards or power plant rules, the EPA calculates the value of avoided CO₂ emissions using the SCC to determine whether benefits outweigh costs. Many U.S. states also use SCC estimates in their own regulatory frameworks.

SCC estimates depend on complex models linking emissions to temperature change, temperature to economic damages, and future damages to present value. Each step involves significant scientific and economic uncertainty. Different discount rates, damage functions, climate sensitivity assumptions, and equity weighting approaches can produce SCC values ranging from under $10 to over $200 per tonne of CO₂. The EPA's 2023 central estimate is around $190/tonne.

This calculator covers the major greenhouse gases for which federal social cost estimates exist: carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), HFC-125, and HFC-134a. Non-CO₂ gases are converted to CO₂ equivalents using GWP multipliers before the social cost value is applied, giving you a comparable economic damage estimate regardless of which gas you're evaluating.