How Is The Social Cost Of Carbon Calculated

Use this interactive calculator to estimate the present value of future climate damages from carbon dioxide emissions. The model below applies a simplified integrated assessment approach: it projects annual damages per ton, grows those damages over time, and discounts them back to today.

Method Discounted damages

Unit result $/metric ton CO2

Policy use Cost-benefit analysis

Expert Guide: How the Social Cost of Carbon Is Calculated

The social cost of carbon, often abbreviated as SCC, is one of the most important concepts in climate economics. It translates climate damage into a monetary value by estimating the present value of future harm caused by emitting one additional metric ton of carbon dioxide. In practical terms, it helps governments, analysts, utilities, and businesses compare the near-term benefits of a project against the long-term climate damages it creates. If a regulation reduces emissions, the SCC can be used to estimate the value of those avoided damages. If a policy increases emissions, the SCC can be used to estimate the societal cost imposed on current and future generations.

What the social cost of carbon measures

The SCC is not simply a fuel tax, a carbon market price, or the cost of removing carbon from the atmosphere. Instead, it is an estimate of the monetized damages associated with one incremental ton of CO2 emissions in a given year. Those damages can include agricultural losses, sea-level rise, heat-related mortality, lower labor productivity, ecosystem disruption, and energy system impacts. In many modern policy frameworks, the SCC is used inside regulatory impact analysis to place a dollar value on emission changes over time.

Because the consequences of CO2 unfold over decades and even centuries, the SCC requires a long-run modeling framework. Analysts must estimate how a pulse of emissions changes atmospheric concentrations, how those concentrations influence temperature, how warming changes economic and physical outcomes, and how those damages are valued today. This is why SCC estimates are usually produced with integrated assessment models, often called IAMs.

The basic formula behind the SCC

At its core, the social cost of carbon is a present-value calculation. The conceptual formula is:

1. Estimate the additional climate damages in each future year caused by one extra metric ton of CO2 emitted today.
2. Discount those future annual damages back to present dollars.
3. Sum the discounted damages across the full time horizon.

Written more simply, the SCC can be thought of as:

SCC = Sum of future marginal damages / discounted to today

The calculator above uses a simplified educational version of that logic. It starts with an initial damage per ton, applies a climate sensitivity multiplier, grows damages over time, and then discounts them back using the selected discount rate. This is not a substitute for a full federal integrated assessment model, but it mirrors the economic structure that makes the SCC useful.

The four major building blocks in calculation

• Emissions pathway: Analysts identify the extra ton of CO2 and how it affects atmospheric concentrations over time.
• Climate response: Models estimate how the atmosphere and oceans respond, including temperature change, carbon cycling, and persistence.
• Damage function: Economists estimate how warming affects agriculture, mortality, coastal assets, labor, energy demand, and other sectors.
• Discounting: Future damages are converted into present-value terms using a social discount rate.

Each one of these steps can materially change the final SCC estimate. That is why published SCC values vary across time, countries, and methodologies.

Why discount rates matter so much

A dollar of damage occurring fifty or one hundred years from now is not usually treated the same as a dollar of damage today. Economists discount future damages to reflect time preference, opportunity cost of capital, uncertainty, and intergenerational welfare judgments. In SCC work, the discount rate is often the single most influential assumption.

Lower discount rates generally produce a much higher social cost of carbon because they place greater weight on harms experienced by future generations. Higher discount rates produce lower SCC values because distant damages count for less in present-value terms. This debate is not purely technical. It is deeply ethical because it influences how much current society should spend now to protect people in the future.

Discount assumption	Illustrative U.S. government SCC for 2020 emissions	Interpretation
5.0%	$14 per metric ton CO2	Future damages are discounted heavily, producing a lower SCC.
3.0%	$51 per metric ton CO2	Central interim U.S. estimate used in many regulatory analyses.
2.5%	$76 per metric ton CO2	Greater weight on long-run damages raises the value substantially.
95th percentile at 3.0%	$152 per metric ton CO2	Captures higher-end damage risk rather than only the average case.

These figures are drawn from the U.S. Interagency Working Group interim estimates for 2020 emissions, expressed in 2007 dollars. They are useful because they show how the exact same underlying emissions can produce dramatically different values depending on assumptions about uncertainty and discounting.

Integrated assessment models used in practice

Historically, government agencies have relied on a family of integrated assessment models such as DICE, FUND, and PAGE. These models combine climate science and economics into a single framework. They take an emissions shock, simulate atmospheric concentration changes, estimate warming, and then monetize economic damage across time.

In simple terms:

1. The model adds one extra ton of CO2 emissions in a target year.
2. It estimates how much additional warming results from that extra ton.
3. It translates that warming into marginal damage in each future year.
4. It discounts each year of damage and sums the result.

Modern policy analysis increasingly seeks to improve these models by incorporating updated climate science, better mortality estimates, richer treatment of inequality, and stronger representation of low-probability catastrophic risks.

Key data inputs that influence the result

When people ask, “How is the social cost of carbon calculated?” the most honest answer is that it depends on a chain of assumptions. Important inputs include:

• Baseline emissions trajectories: Future global emissions affect atmospheric accumulation and temperature pathways.
• Climate sensitivity: This is the estimated temperature response to increased greenhouse gas concentrations.
• Socioeconomic projections: Population growth, income growth, and regional development affect both vulnerability and the value of damages.
• Sectoral damage estimates: Agriculture, coastal flooding, human health, energy demand, and labor productivity all matter.
• Discount rate and risk treatment: These shape the final present-value estimate.

In the calculator on this page, these complexities are represented in a transparent simplified way using an initial damage estimate, a damage growth rate, a time horizon, and a sensitivity multiplier. That design helps users understand the structure of SCC without needing a full federal model.

How the calculator on this page works

This calculator estimates SCC using a discounted stream of marginal damages. Specifically, it applies the following steps:

1. Take the user-entered initial damage per ton.
2. Multiply it by the selected climate sensitivity scenario.
3. Increase that damage each year by the annual damage growth rate.
4. Discount each year back by the chosen discount rate.
5. Sum all discounted annual damages to get the social cost of carbon per ton.
6. Multiply by the selected emissions volume to estimate the total social cost.

This gives you a clear present-value estimate of climate damages under your assumptions. It is intentionally educational. Real-world governmental estimates usually model global climate systems, region-specific damage pathways, socioeconomic feedbacks, and uncertainty distributions more explicitly.

Comparison table: how assumptions change SCC outcomes

Assumption change	Expected effect on SCC	Reason
Lower discount rate	Higher SCC	Future damages receive more present-day weight.
Higher climate sensitivity	Higher SCC	Extra CO2 causes greater warming and larger damages.
Higher damage growth rate	Higher SCC	Marginal damages rise faster over time.
Shorter time horizon	Lower SCC	Long-tail climate damages are excluded from the sum.
Including catastrophic tail risk	Higher SCC	Low-probability, high-damage outcomes increase expected loss.

Real-world context and statistics

The importance of SCC becomes more obvious when paired with the scale of global emissions and atmospheric concentration change. Atmospheric carbon dioxide concentrations have risen from roughly preindustrial levels near 280 parts per million to over 420 parts per million in recent years, according to U.S. scientific monitoring. That accumulation is why marginal emissions matter. Even one additional ton contributes to a stock pollutant that remains in the climate system for a very long time.

At the policy level, a change of just a few dollars per ton can affect billions of dollars in estimated benefits or costs when applied across power generation, transportation, industrial regulation, methane leakage mitigation, or appliance efficiency standards. If a rule reduces emissions by 10 million metric tons, the monetized climate benefit at $51 per ton is about $510 million. At $190 per ton, that same reduction is worth $1.9 billion. This is why agencies devote significant effort to updating SCC methodologies.

Domestic versus global damages

Another major methodological question is whether the SCC should reflect only domestic damages or global damages. Because climate change is driven by globally mixed pollutants, one ton emitted anywhere contributes to worldwide harm. The U.S. government has historically used a global SCC in federal analysis, reflecting both the transboundary nature of climate damages and reciprocal international policy logic. Critics sometimes argue for a domestic-only metric, but most climate policy economists note that global spillovers are central to the problem.

From a practical standpoint, a global SCC is also more consistent with the science of atmospheric mixing and the economics of international cooperation. Climate damages do not stop at national borders, and domestic welfare is affected by global instability, trade shocks, migration pressure, and geopolitical risk.

Uncertainty and why there is no single permanent SCC number

People often look for one official number, but the SCC is better understood as a decision tool built from evolving evidence. Climate sensitivity estimates improve. Damage functions are refined. Mortality impacts from extreme heat are studied more rigorously. Economic growth assumptions change. Discount rate frameworks are debated. Because the underlying science and economics evolve, SCC estimates also evolve.

That does not make the metric unreliable. It means it should be updated as evidence improves, just like other major public policy parameters. In fact, uncertainty is one reason many analysts support using scenario ranges, central values, and high-damage sensitivity cases rather than pretending there is a single exact number that is permanently correct.

Practical takeaway: The social cost of carbon is calculated by estimating future marginal climate damages from one additional ton of CO2 and discounting those damages into present-value dollars. The result depends heavily on the damage pathway, discount rate, climate sensitivity, and time horizon selected.

Authoritative sources for deeper reading

• U.S. Environmental Protection Agency: Social Cost of Greenhouse Gases
• White House Technical Support Document on the Social Cost of Carbon
• Columbia University overview of why the social cost of carbon matters

Final conclusion

If you want the shortest accurate answer to the question “how is the social cost of carbon calculated,” it is this: analysts estimate the stream of future damages caused by one additional ton of CO2, then discount those damages back to the present and sum them. Everything else is about how carefully that stream of damages is modeled. The best SCC work combines climate science, economics, risk analysis, and ethics. That is why the measure has become central to modern cost-benefit analysis for climate and energy policy.

The calculator above lets you test the intuition for yourself. Change the discount rate, increase the damage growth assumption, or move from a central to a high-sensitivity scenario. You will immediately see the same lesson found in the policy literature: the social cost of carbon is not arbitrary, but it is highly sensitive to the assumptions society chooses about future harm and how much those future harms should count today.