What Is GWP-100? Why Are Greenhouse Gases Weighted Differently?

Have you ever wondered why an emissions report shows "28 kg CO2e" instead of "1 kg of methane leak"? The answer: GWP-100. In this guide, we explain what this concept is, how the formula works, and what it means in practice for a gas to have a LARGE GWP value.

What Is GWP-100?

GWP (Global Warming Potential) is a multiplier that shows how much warming effect a greenhouse gas has in the atmosphere compared to 1 kg of CO2. The "100" indicates that this effect is measured over a 100-year time horizon — this is the standard time horizon used in IPCC AR6 (the Sixth Assessment Report) and in the UNFCCC's official national greenhouse gas reporting.

The Formula: Why So Simple, Yet So Important?

kg CO2e = kg of Gas × GWP-100 Multiplier

The formula is mathematically extremely simple — a single multiplication. But its importance comes from this: for some gases the multiplier is in the THOUSANDS, so a relatively small physical quantity (a few kg) can translate into a massive CO2 equivalent.

GWP-100 Values by Gas

You can find the FULL list of all 17 fugitive refrigerant gases in the Scope 1&2 section of our Bibliography page.

How Do You Interpret Your Result? — Prioritizing by GWP Magnitude

The HIGHER a gas's GWP value, the more priority you should give to preventing its leaks — because the same physical leak quantity (e.g. 1 kg) translates into a vastly different-sized emission impact:

• GWP > 10,000 (like SF6, NF3): Even the smallest leak creates a massive emission impact — leak-tightness inspection and maintenance of this equipment should be the HIGHEST priority.
• GWP 1,000-10,000 (most HFC refrigerants): Regular maintenance of commercial/industrial refrigeration systems is important; switching to low-GWP alternatives (gases with GWP<700, like R-32, R-290) should be considered where possible.
• GWP 1-300 (CO2, CH4, N2O): These are usually released in far larger volumes (combustion, agriculture, waste), so despite the low multiplier, their total impact can still be large — here the priority is reducing volume, not the multiplier.

Worked Example

A 5 kg SF6 leak from an electricity distribution facility = 5 kg × 23,500 (GWP-100) = 117,500 kg CO2e

Comparison: The same facility's annual electricity consumption of 200,000 kWh = 200,000 × 0.442 kg CO2e/kWh = 88,400 kg CO2e — meaning a 5 kg gas leak is equivalent to MORE emissions than the facility's ENTIRE YEAR of electricity consumption.