Greenhouse Gas Emissions

When weighting the welfare of current and future generations equally (corresponds to a rate of pure time preference (PRTP) of zero percent), we recommend using a value factor of 990 Euro2025 / t for CO2-equivalent (CO2-eq) emissions occurring in 2025. When placing a higher weight on the welfare of current compared to future generations (one percent PRTP), we recommend a value factor of 345 Euro2025 / t CO2-eq. In addition, we recommend a sensitivity analysis with the respective other value.

These recommendations follow a damage cost concept known as the Social Cost of Carbon (SCC). They are based on an adapted version of the Greenhouse Gas Impact Value Estimator (GIVE) model (Rennert et al. 2022).

The emission of greenhouse gases leads to significant economic and societal damages.

Source: Umweltbundesamt

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The most important aspects with respect to the value factors on greenhouse gas emissions and their use are:

• Use of two different time preference parameters: a pure rate of time preference (PRTP) of zero percent, which reflects an equal weight of the welfare of future and present generations, and a PRTP of one percent, which reflects a considerably lower weight on the welfare of future generations (with PRTPs being different from discount rates, see below).
• Use of equity weighting to account for impacts in different world regions (Prest et al. 2024, Anthoff 2025).
• The above table recommends value factors for the greenhouse gases carbon dioxide (CO2), methane (CH4) as well as nitrous oxide (N2O). When detailed information on the emission of these three greenhouse gases is available, we recommend using the respective value factors. If, however, data is only available on the emission of CO2-equivalents, we recommend using the CO2 value factors as a proxy.
• The Global Warming Potential with a time horizon of 100 years (GWP100) as recommended by the Intergovernmental Panel on Climate Change (IPCC) (see IPCC Assessment Report (AR) 6 (2022), or IPCC AR7 upon publication), can be used to transfer the carbon dioxide value factors to greenhouse gases which are not included in the above table or to convert emission data for other greenhouse gases into CO2-equivalents.
• To obtain value factors for years for which no values are given in Table 1, we recommend using linear interpolation between the shown value factors.
• For a price adjustment of the value factors, we recommend using the consumer price index (for Germany, see Destatis 2025). Stating EURO2025 or price level of 2025 means that the price development (inflation) has been taken into account until the end of 2024).
• When using the above value factors to assess the impacts of greenhouse gas emissions in the aviation sector, note that combustion processes develop a higher damage potential at high altitudes (see UBA 2023). The specific emission weighting factor for individual flights depends on a range of parameters, such as the time and location of the emissions and the weather conditions, and can vary substantially. If no specific value for the emission weighting factor for individual flights is available, an emission weighting factor of 3 can be used as an approximation (UBA 2025).

The GIVE model

To assess the environmental impacts of greenhouse gas emissions, we use Social Cost of Carbon (SCC). This is a damage cost concept valuing the global impacts or damages resulting from greenhouse gas emissions.

The Social Cost of Carbon estimates in the above table, are based on the open-source integrated assessment model GIVE introduced in 2022. In a first step, projections regarding the economic and demographic development serve as predictors of a future greenhouse gas emissions pathway. Secondly, the projected emissions pathway is fed into a climate module, which models greenhouse gas concentrations, temperature increases and sea level rise. Thirdly, the modelled impacts of climate change on different sectors are monetized, aggregated and converted into a present value by means of discounting.

The estimates from the GIVE model comprise four impact categories: agriculture, health (through heat related mortality), building energy consumption and sea level rise. Through the aggregation over four impact categories, the GIVE model covers a range of climate change effects. However, it is crucial to note that a large number of impact categories and effects are not or not fully considered, such as tipping points, migration, conflict, impacts on biodiversity, extreme weather events or labor productivity. The integration of these and other impacts into the model framework is likely to increase the climate damage cost estimates by at least an order of magnitude.

Discounting and the pure rate of time preference 

The time at which the costs and benefits of today's decisions materialize plays an important role in economic analyses. To compare present and future costs and benefits, future outcomes are discounted to the present day using a discount rate. This discount rate is to reflect two aspects: Firstly, the individual or societal time preference and, secondly, the relative change between present and future prices of different goods and services.

1. The individual or social time preference, captured in the Pure Rate of Time Preference (PRTP) reflects the degree to which individuals or society as a whole prefer or value present goods and services over future ones. A PRTP of zero percent reflects the normative assumption that the utility (“welfare”) of future and present generations should be weighed equally. In contrast, a PRTP larger than zero percent reflects the normative assumption that the well-being of present generations should be weighed higher than the well-being of future generations.
2. The relative change between present and future prices of different goods and services. The common assumption for goods and services included in Gross Domestic Product (GDP) and consumption measures is to become more abundant in the future as GDP and consumption are both expected to grow. Hence, their relative prices are expected to decrease, increasing the discount rate for these goods and services. In contrast, the provision of many ecosystem services declines due to habitat degradation, climate change and biodiversity loss. Accordingly, there is consensus that a lower discount rate must be applied for the economic valuation of most environmental impacts to account for an increase in relative scarcity of benefits provided by ecosystems, which results in relative price increases (e.g., Drupp et al. 2024).

In the GIVE model we use the social discount rate developed by Frank Ramsey (Ramsey 1928), which combines the two aspects above: expected consumption growth, weighted by its effect on the marginal utility of consumers, and the pure rate of time preference (PRTP).

In the GIVE model the consumption growth rate is a dependent variable. Therefore, it is not possible to specify the exact discount rate used for the climate costs in the above table. However, we can keep the Pure Rate of Time Preference constant. Results are presented for a PRTP of zero and one percent, reflecting different weights on current and future welfare.

Equity weighting

The effects of climate change are global. They occur irrespective of where greenhouse gases are emitted. Accordingly, every tonne of greenhouse gas which is emitted in Germany results in damages all around the world. However, due to the differences in economic wealth across the globe in various regions of the world, comparable damages correspond to different nominal monetary values. If, for example, residential buildings are destroyed by extreme weather events, their material value is on average higher in richer countries than in poorer countries. However, the people in poorer countries are at least as much affected in terms of their quality of life (their "utility" or “welfare” in economic terms) as people in richer countries. This is often even more the case, due to the lack of insurance and government aid. It is also nominally cheaper to restore the damage incurred (for example, repairing buildings and the infrastructure) in poorer countries. However, the resulting loss of utility per monetary unit used for the repairs is also greater. These differences in wealth can be accounted for in the assessment of global climate damage by using equity weighting.

Since UBA’s first publication of the handbook Methodological Convention 1.0 in 2007, we have recommended the use of equity weighting to equally consider the welfare effects on all humans. Using German equity weights implies that we estimate costs as if all damages caused by one tonne (metric tonne) of GHG were incurred entirely in Germany, or as if the world shared the same income level as Germany. Differences in income within Germany are not considered, that is, the damage is valued as if climate impacts affect the poorer and richer parts of the population equally.

Anthoff, D. (2007): Report on marginal external damage costs inventory of greenhouse gas emissions. NEEDS Delivery no. 5.4-RS 1b.

Anthoff, D. (2025): Erweiterung des GIVE-Modells um Klimakostensätze für equity weighted zukünftige Emissionsjahre und Klimagase, Berkeley, USA, available upon request from UBA.

Destatis (2025): Consumer Price Index (12.05.2025).

Drupp, M. A.; Hänsel, M. C.; Fenichel, E. P.; Freeman, M.; Gollier, C.; Groom, B.; Heal, G. M.; Howard, P. H.; Millner, A.; Moore, F. C.; Nesje, F.; Quaas, M. F.; Smulders, S.; Sterner, T.; Traeger, C.; Venmans, F. (2024): Accounting for the increasing benefits from scarce ecosystems. In: Science, 2024, 383(6687), AAAS, Washington, D.C., 1062–1064.

IPCC (2022): Climate Change 2022: Impacts, Adaptation, and Vulnerability. Working Group II contribution to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK and New York, NY, USA, Cambridge University Press.

Prest, B. C.; Rennels, L.; Errickson, F.; Anthoff, D. (2024): Equity weighting increases the social cost of carbon - New government guidelines could transform benefit-cost analysis of US climate policy. In: Science, 2024, 385(6710), AAAS, Washington, D. C., 715-717.

Ramsey, F. P. (1928): A Mathematical Theory of Saving. In: The Economic Journal 38(152), Oxford University Press, 543-559.

Rennert, K.; Errickson, F.; Prest, B. C.; Rennels, L.; Newell, R. G.; Pizer, W.; Kingdon, C.; Wingenroth, J.; Cooke, R.; Parthum, B.; Smith, D.; Cromar, K.; Diaz, D.; Moore, F. C.; Müller, U. K.; Plevin, R. J.; Raftery, A. E.; Sevcikova, H.; Sheets, H.; Stock, J. H.; Tan, T.; Watson, M.; Wong, T. E.; Anthoff, D. (2022): Comprehensive evidence implies a higher social cost of CO₂. In: Nature, 2022, 610(7933), Springer, 687–692.

UBA (2023): Klimawirkung des Luftverkehrs - Wissenschaftlicher Kenntnisstand, Entwicklungen und Maßnahmen, Dessau-Roßlau.

UBA (2025): CO2-Rechner des Umweltbundesamtes. (18.07.2025).