Domain: Energy
Question:
A company has built its multi-year Scope 1 inventory, trendline forecasting, and emissions-reduction target tracking on AR4 GWPs, but EPA's GHGRP rule revisions require updated GWPs to be incorporated into Reporting Year 2024 submissions (with EPA adopting AR5 GWPs broadly and AR6 GWPs for certain gases without AR5 chemical-specific values). 
The company's footprint is disproportionately methane- and F-gas-heavy (so CO₂e totals are sensitive to GWP updates), and leadership wants to avoid a "paper increase/decrease" that could be misread as real operational change while still meeting the GHG Protocol principles of accuracy and consistency across historical, current, and forward-looking reporting. Using an internal significance threshold (e.g., 5%) as the decision trigger, what governance approach should the company use to (a) quantify and attribute the AR4→updated-GWP delta versus real emissions performance, (b) decide whether to restate historical inventories (or transparently not restate), and (c) manage knock-on effects where the revised CO₂e totals could push facilities across the 25,000 mtCO₂e GHGRP reporting threshold in either direction--especially given that GHGRP time series consistency may be handled differently than the company's internal threshold logic?

Expected points in a correct answer:
States that Global Warming Potential (GWP) values provide a way to convert the global warming potential of various GHGs into carbon dioxide equivalent (CO2e).
States that GWP values are typically calculated over a 100-year time horizon.
States that new GWP values are periodically released based on the latest climate science.
States that using the most recent GWP values is generally recommended as they are considered the most accurate
States that companies with large emissions of methane, nitrous oxide, fluorinated gases, and HFCs generally see the most significant changes between GWP updates.
States that accuracy is a core reporting principle under the GHG Protocol.
States that consistency is a core reporting principle under the GHG Protocol.
States that an abrupt change from AR4 to AR6 without restating could cause historical reporting to appear inconsistent with current and future reporting.
States that inconsistency could impact progress toward existing or future emissions reduction targets depending on the significance of the change.
Provides option 1: move to AR6 now and do not restate historical values if the recalculated change is below the internal significance threshold.
States that under option 1, the company should transparently note the difference in GWP values between historical and current/future reporting.
Provides option 2: move to AR6 now and restate all relevant historical values if the internal significance threshold is crossed or the company prefers uniform GWP values.
Presents option 3: wait to move to AR6 until the significance threshold is crossed, continuing to use AR4 with ongoing monitoring of both scenarios.
States that the company should use a significance threshold (e.g., 5%) to determine if and when to change GWP values.
States that the company should recalculate its historical emissions using the new GWP values to quantify the difference between the quantities in AR4 and AR6.
States that changes in GWP values and resulting emissions could cause companies to cross the GHGRP reporting threshold (25,000 mtCO2e) in either direction.
States that the company should monitor and quantify the impact of new GWP values even if not officially adopted in its own reporting.
States that the GHGRP appears to be capable of updating historical data within its system with new GWP values on behalf of emitters.
States that if the GHGRP were to move to AR6 values, it should update all historically reported data regardless of significance threshold to present a consistent time series.
States that under option 3 (continuing with AR4), the company should transparently explain why it has not yet adopted updated GWP values.
States that the GHGRP's approach to time series consistency (updating all historical data) may differ from the company's own internal significance threshold approach.
States that the company should leverage updated GHGRP historical data (when available) to help understand the significance of a GWP change.
References the GHGRP's prior approach to reporting year 2013 as precedent for how the program handles GWP updates to historical data.
States that the company should be mindful of the potential impact a GWP change might have on its GHGRP reporting obligation.