Updated GWP Values for Greenhouse Gases

Summary#

This Order updates the list of greenhouse gases and the numbers used to convert them into carbon-dioxide-equivalents in Schedule 3 to the Greenhouse Gas Pollution Pricing Act. The new values come from the IPCC Fifth Assessment Report and take effect on January 1, 2023.

What it does#

• Replaces many global warming potential (GWP) numbers in Schedule 3 to the Greenhouse Gas Pollution Pricing Act with the updated values from the IPCC Fifth Assessment Report (AR5).
• Clarifies some gas names by adding acronyms for perfluorocarbons (PFCs) alongside their molecular formulas.
• Examples of changed GWPs (old AR4 → new AR5 values are shown in the Canada Gazette table):
  • Methane (CH4): 25 → 28
  • Nitrous oxide (N2O): 298 → 265
  • Sulfur hexafluoride (SF6): 22,800 → 23,500
  • Several hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) also have higher or lower GWPs (see the Gazette table for full list).
• The Order’s changes come into force on January 1, 2023.

Note: the Gazette’s accompanying Regulatory Impact Analysis Statement also discusses related carbon-pricing changes (for example, the excess emissions charge used in the Output-Based Pricing System), but the formal text of this Order updates Schedule 3 GWPs.

Who's affected#

• Facilities and companies that report or account for greenhouse gases under Part 2 of the Greenhouse Gas Pollution Pricing Act, including those in the federal Output-Based Pricing System (OBPS).
• Project proponents in the federal offset credit system who measure emissions reductions for credits.
• Regulators and anyone who converts non-CO2 gases into carbon-dioxide-equivalent (CO2e) for reporting to Canada’s National Inventory Report (NIR) and international bodies such as the UNFCCC.
• If it is unclear how large the effect will be for a specific facility or project, that depends on the facility’s mix of gases (for example, how much methane versus nitrous oxide it emits).

Why it matters#

• GWPs are the numbers used to turn different greenhouse gases into a single CO2e figure. Changing those numbers changes reported emissions totals, emissions limits expressed in CO2e, and the number of credits or compliance obligations a facility has.
• Because methane’s GWP increased (to 28) and nitrous oxide’s decreased (to 265), facilities with methane-heavy emissions may see their reported CO2e rise, while those with more nitrous-oxide emissions may see reported CO2e fall.
• The change aligns Canada’s reporting and compliance metrics with updated scientific guidance (AR5) and with international reporting under the UNFCCC, helping keep Canada’s inventory and pricing rules consistent.
• The practical impact for any one business or project will vary. Some will see small adjustments to their reported emissions or credits; others could see more noticeable changes if they emit significant amounts of gases whose GWPs shifted.