August 2021

The new Sixth Assessment Report from the IPCC (AR6) has caused headlines around the world and stresses the urgency of the climate challenge. The report will provoke governments to strengthen their climate policies and requires companies to update their greenhouse gas emission calculations to follow the latest scientific understanding.

At ERC Evolution, we will be updating our emission calculations to account for the new global warming potentials (GWP). GWPs are multipliers applied to greenhouse gases such as methane (CH₄) and Nitrous Oxide (N₂O) to equate the impact they have on the Earth’s temperature with that of Carbon Dioxide (CO₂). The AR6 GWP values have been refined since the Fifth Assessment Report (AR5) to account for changes in radiative properties, atmospheric lifetimes, and indirect contributions of the different gases.

The table below contains the updated AR6 values for the three main greenhouse gases alongside the values reported in the AR4 and AR5 reports for comparison. In the AR6 report, an additional GWP for methane has been included to differentiate between methane which originates from fossil fuel sources, and methane from non-fossil fuel sources, like agriculture.

IPCC Sixth Assessment Report Global Warming Potentials

Does the new report mean your company has to update your calculations, and should you be adopting the 100-year or 20-year GWPs? The answer is not as simple as you might think and depends on regulation in your region and the purpose of your report. However, in the absence of any bespoke requirements, the best practice is to adopt the new AR6 100-year GWPs.

The Paris Rulebook states: ‘ Each Party shall use the 100-year time-horizon global warming potential (GWP) values from the IPCC Fifth Assessment Report, or 100-year time-horizon GWP values from a subsequent IPCC assessment report as agreed upon by the ‘Conference of the Parties serving as the meeting of the Parties to the Paris Agreement’ (CMA), to report aggregate emissions and removals of GHGs, expressed in CO2-eq. Each Party may in addition also use other metrics (e.g., global temperature potential) to report supplemental information on aggregate emissions and removals of GHGs, expressed in CO2-eq“.