The SCC is derived from Integrated Assessment Models (IAM) such as DICE, FUND, and PAGE.^3,4 These models assess the link between the growth of GDP, the aggregation of GHGs, and the resultant damages to the environment for the sake of formulating policies.¹⁵ Through the monetarization of the future impacts of climate change, IAM helps in the formulation of policies for the mitigation of such impacts.¹⁶ IAMs usually couple climate theory with economic models in the following key components:¹⁷

The choice of discount rate—which, among other things, determines the value of future costs relative to the present—is crucial in SCC computations. A higher discount rate yields a lower SCC: it weights current benefits more heavily than future impacts.^3,19,20 Conversely, a low discount rate boosts the SCC by giving greater weight to the well-being of future generations and promoting more far-reaching policies.^4,21 A further integrative element concerns technological change; policy needs to price carbon but also generate incentives for the diffusion of renewable energies.^21,22 While groups such as the U.S. IWG provide SCC values computed from various IAMs, the variability remains high due to differing methodologies regarding risk and catastrophic outcomes.^23,24 One of the most controversial aspects of SCC estimation is the selection of the discount rate. It acts as a fulcrum point for determining how future costs and benefits are weighted in relation to present ones-a kind of bridge that links current investment to future welfare.²³ The rate chosen is by no means simply a technical exercise but a deep, ethical intergenerational equity choice:

However, reaching a consensus in policy formulation remains a challenge. Even when using average values of the SCC — such as those provided by the Interagency Working Group (IWG) — substantial variability persists among estimates. This reflects differences in model structure, assumptions regarding climate damage, and approaches to uncertainty and risk.²⁷

Table 1 presents an illustrative comparison of SCC estimates across models and discount rates. The values presented should be interpreted as indicative ranges synthesized from the literature, and not as precise or directly comparable point estimates.

Table 1 illustrates the sensitivity of SCC estimates to discount rates and modeling assumptions, reinforcing the normative dimension of policy design. Even when similar discount rates are applied, estimates can vary significantly between models due to differences in damage functions, risk treatment, and assumptions about future socioeconomic trajectories.

Ultimately, the choice of discount rate is not merely a technical parameter, but a normative decision that incorporates ethical judgments about the relative value of present versus future well-being. The divergence between approaches with high and low discount rates, exemplified by Nordhaus and Stern, highlights a fundamental tension in climate economics between efficiency and equity. Consequently, estimates of SCC should be interpreted not as objective values, but as constructs relevant to public policy, shaped by underlying social priorities.

Beyond theoretical frameworks, a growing body of empirical literature employs statistical methods to quantify the economic effects of climate change using historical data. These studies are used in the literature to identify and estimate the relationship between temperature variations and key economic indicators, including GDP growth, agricultural productivity, and labor market performance. Typically based on large international or panel datasets, this literature applies econometric techniques to isolate the impact of climatic variables on economic outcomes. The empirical literature consistently indicates that deviations from historical temperature norms have a statistically significant negative effect on economic growth,^24,25 a finding corroborated by a broader body of research on the economic impacts of climate variability.³⁰ Importantly, the relationship between temperature and economic output is not linear, with damages increasing disproportionately when temperatures exceed optimal thresholds. Recent empirical studies also show that climate change has contributed to increased global economic inequality, as warmer regions, more exposed to it, suffer greater income losses than colder regions.³¹ The impacts of climate variability are unevenly distributed, disproportionately affecting low-income countries and climate-sensitive sectors such as agriculture and industry.^10,32 These effects often persist over time, leading to long-term reductions in economic performance. For example, studies in the literature suggest that a 1 °C increase in average annual temperature above historical baselines can have a measurable negative effect on GDP per capita.³² While these estimates vary depending on methodology and data, they consistently point to significant economic damage associated with rising temperatures. These findings should be interpreted as stylized summaries of the empirical literature, and not as results derived from a new model presented in this article.

As illustrated in Figure 2, the relationship between temperature anomalies and economic performance reflects this non-linear dynamic. Taken together, the empirical literature reinforces the theoretical predictions of climate damage functions and highlights the potential for substantial underestimation of costs in models that assume gradual or linear impacts.^24,25,30 This evidence reinforces the need for preventive and proactive policy interventions, especially in regions most vulnerable to climate impacts.

Within the framework proposed in this article, these insights primarily inform the efficiency dimension of climate policy and highlight the importance of integrating distributional and political considerations into policymaking.

Carbon pricing, in essence, aims to impose a cost on emissions to reflect their environmental and social impacts, thereby correcting the market failure, since these costs are otherwise not considered. Two major market instruments include carbon taxes and cap-and-trade systems. Carbon taxes are charges levied on every ton of carbon content of fossil fuels. This system has the advantage of creating a straightforward pricing system for carbon emissions, as it sends a strong signal to firms and households to shift to cleaner resources in the long run. Empirical evidence in the literature suggests that carbon pricing mechanisms are effective. Comparative analyses between countries show that jurisdictions that implement carbon pricing policies experience statistically significant reductions in emissions compared to jurisdictions that do not adopt this practice.^33,34

Many carbon experts often advocate it as an easily manageable system in terms of transparency and administrative ease for the government.³⁵ Furthermore, these taxes have the benefit of creating enough funds that can be “recycled,” for instance, in terms of investing in converting environmental infrastructure.^36,37 However, there are several political and economic pitfalls associated with carbon taxes. One of the key issues with carbon taxes is carbon leakage. When a country imposes a carbon tax on its domestic industries, making them comparatively less competitive than their global counterparts in other regions where the carbon prices are not set similarly.^38,39 As an alternative, cap-and-trade policies or carbon trading mechanisms set a strict target, or “cap,” on total emissions within a particular sector of the economy.

The government then sets a finite number of carbon emissions allowances. These allowances are tradeable in a market.⁴⁰ As opposed to a carbon tax rate, the carbon price is subject to the market forces of demand and supply. With a carbon tax, industries get certainty of the carbon price. With cap-and-trade policies, the environmental target is guaranteed. No matter what the carbon price is, the overall emissions target is fulfilled.^18,41 The most successful examples of cap-and-trade policies are the European Union Emissions Trading Scheme (EU ETS) and other regional markets in North America.^42,43 While effective, the inherent price volatility in these markets can occasionally complicate long-term capital planning for participating firms. A detailed comparison is presented in Table 2.

Despite its solid theoretical basis, the practical effectiveness of carbon pricing is often limited by political and economic factors. Issues such as carbon leakage, distributional impacts, and public resistance can significantly weaken policy implementation.^38,39 Furthermore, while carbon taxes provide price predictability and emissions trading systems ensure emissions predictability, neither instrument alone is sufficient to address the scale and urgency of the climate challenge.^18,41 This underscores the need for complementary policies that enhance both effectiveness and political feasibility.

While carbon pricing increases the cost of carbon-intensive energy, subsidies for green technology reward low-carbon alternatives, acting like a “carrot” approach. By reducing the relative cost of clean technology through feed-in tariffs for renewable electricity and tax credits for electric vehicle production, for instance, these mechanisms enable clean technology to compete more effectively with fossil fuels.²⁸ Government intervention is paramount in addressing market failures in research and development. Private firms are usually quite risk-averse, frequently avoiding the high upfront costs and the uncertainty associated with cutting-edge clean technologies. Correspondingly, public funding catalyzes innovation by producing “public goods” in the form of spillovers that benefit the wider economy.^11,44 Emphasizing subsidies as investments in job creation and industrial growth remains generally more politically palatable than the “stick” of taxation and thus often enjoys broader public support.

Within the framework proposed in this article, these policy instruments play distinct yet complementary roles. Carbon pricing primarily addresses the efficiency dimension by internalizing external costs, while subsidies and public investment contribute to the equity and policy viability dimensions by supporting technological transitions and reducing resistance to policy implementation. This highlights that no single instrument is sufficient, reinforcing the need for integrated policy packages that balance these three dimensions.

A basic problem in climate policy is a temporal disconnect between costs and benefits. Carbon taxes and the like impose an immediate and concentrated cost on consumers through higher energy and fuel prices. Their benefits, by contrast, are diffused over decades and come primarily in the form of future ecological stability and avoided climate damages.⁵ This creates a type of “political discount rate” whereby elected officials focused on short-term election cycles are incentivized to delay or dilute aggressive climate action to avoid immediate voter backlash. This behavioral bias, often modeled as hyperbolic discounting, leads society to overvalue immediate rewards while undervaluing large future risks.⁶

Climate change is an archetypal global public goods problem, as emphasized in the literature on collective action and common-pool resource governance.²² Climate stability is a non-excludable and non-rivalrous good that creates a strong “free-riding” problem. National governments might be tempted to make other countries share the cost burden of cutting emissions while enjoying the global benefits of mitigation themselves.^13,46 The Paris Agreement tries to remedy this situation with the use of NDCs through transparency and international public pressure, rather than through a centralized mechanism for enforcement.^47,48 Without a “climate club” reflecting broader coordination challenges in global climate governance,²³ or a better system for discouraging non-compliance, free-riding remains a major impediment to the necessary global coverage.^49,50 One proposed solution to the free-rider problem is the formation of “climate clubs,” in which participating countries adopt coordinated carbon prices and impose penalties on non-members, thus creating incentives for broader cooperation.⁵¹

The fossil fuel industry and its associated lobbies wield political power to maintain the status quo. Actors whose business models are centered on the consumption of carbon-intensive resources engage in strong lobbying to influence public debate and, hence, get the legislature to act in ways that delay action on climate change.^8,52 Such is the concentration that it can lead to political gridlock or formulate policies that are insufficient to address the scale of the challenge.^7,53

Moreover, there is a strong incumbency effect in the global economy. This is because the infrastructure, human capital, and finance sectors of the economy are highly intertwined with fossil fuel production. Thus, transitioning from the current economy to a green economy is often viewed as high-risk. This is a source of resistance and must be addressed not only through carbon pricing but also through “green industrial policies” and a “just transition” strategy. The influence of these actors is illustrated in Figure 3.

Within the framework proposed in this article, these political-economy barriers primarily constrain the political-feasibility dimension of climate policy and interact with efficiency and equity. The mismatch between time horizons reduces the political acceptability of efficient policies, collective action problems limit the effectiveness of unilateral measures, and vested interests shape the distributive outcomes of policy design. Together, these constraints reinforce the need for integrated policy packages that explicitly consider political viability, economic efficiency, and social equity.

One of the main political challenges of carbon pricing is its potentially regressive impact, since low-income households typically spend a larger share of their income on energy. The carbon dividend approach addresses this issue by redistributing carbon pricing revenues to citizens through equal, lump-sum transfers.^48,54 This mechanism mitigates the increase in energy costs while preserving the price signal needed to incentivize emissions reductions. By transforming a carbon tax into a visible financial benefit, the policy increases social equity and public acceptance. Within the proposed framework, carbon dividends primarily address the equity dimension of climate policy while reinforcing the political viability of carbon pricing.

Market-driven innovation, on its own, may not occur at the speed necessary to support the climate transition. Green industrial policy, therefore, plays a crucial role in addressing innovation-related market failures by supporting research and development and facilitating the deployment of emerging clean technologies.^14,50,55 Public investment in areas such as smart grids, energy storage, and green hydrogen helps create the infrastructure and market conditions necessary for private investment to follow. Furthermore, this approach reframes climate policy, shifting the narrative from economic costs to economic opportunities, emphasizing job creation and industrial competitiveness in the emerging low-carbon economy. Within the proposed framework, industrial policy primarily contributes to political viability by reducing resistance to climate action and accelerating structural transformation, while supporting long-term efficiency gains through technological change.

Climate change represents a global collective action problem, in which countries face incentives to free-ride on others’ mitigation efforts without contributing to the positive outcome. At the same time, unilateral climate policies can lead to carbon leakage, as companies relocate production to jurisdictions with more lenient environmental regulations. Border Carbon Adjustments (BCAs) have emerged as a policy instrument to address both challenges, imposing a carbon-related tax on imports based on their embodied emissions.^32,36 This mechanism aims to level the playing field between domestic and foreign producers while maintaining incentives for reducing global emissions. A prominent example is the European Union’s BCA Mechanism, which represents one of the most advanced implementations of this approach.

Within the proposed framework, BCAs contribute to both efficiency and policy viability, reducing carbon leakage and strengthening incentives for international coordination. However, its implementation raises significant challenges related to measurement, trade rules, and geopolitical tensions.

A comparison of climate policy instruments highlights the trade-offs inherent in their design. As Table 3 shows, the choice between carbon taxes and emissions trading systems reflects a fundamental distinction between price certainty and emissions certainty, as well as differences in administrative complexity and political feasibility.

Taken together, these policy instruments illustrate the central insight of the framework proposed in this article: effective climate policy cannot rely on isolated measures, but requires coordinated policy packages that balance economic efficiency, social equity, and political viability. Carbon pricing provides the necessary price signal, redistribution mechanisms increase social acceptability, and industrial and international policies address structural and coordination constraints. This integrated approach offers a practical basis for designing climate policies that are both theoretically sound and politically viable.