GWPWerten

GWPWerten, or Global Warming Potential values, are dimensionless numbers used to compare the warming impact of different greenhouse gases relative to carbon dioxide over a specified time horizon. They express how much heat a unit of a given gas traps in the atmosphere compared with the same amount of CO2, enabling emissions of various gases to be expressed as CO2-equivalents (CO2e). This simplifies accounting in inventories, policy, and life cycle assessment.

Determination and horizons: GWPWerten are estimated through climate models and summarized in major assessments such as those by the IPCC. The most common horizons are 20 years and 100 years. By definition, CO2 has a GWP of 1. Methane (CH4) typically has a higher GWP than CO2—for example, about 28–34 over 100 years (and around 84 over 20 years). Nitrous oxide (N2O) is often cited around 265–298 over 100 years. Many fluorinated gases (HFCs, PFCs, SF6) have substantially higher values, which vary widely by gas and horizon. Values are periodically updated as scientific understanding evolves.

Uses and limitations: GWPWerten are widely used in national greenhouse gas inventories, regulatory frameworks, emissions trading, product labeling, and life cycle assessment to aggregate diverse gas emissions into a single metric. However, they have limitations: they depend on the chosen time horizon, assume fixed radiative efficiency and lifetimes, and do not fully capture regional impacts, feedbacks, or non-climate effects. Critics also note that GWP may misrepresent near-term versus long-term climate effects for certain gases. Alternatives and refinements, such as GTP (global temperature potential) or GWP*, have been proposed to address some of these shortcomings.