Our purpose is to encourage accounting regulators to address diversity in practice in the reporting of environmental liabilities. When Canada changed to IFRS in 2011, Canadian regulators asked the IFRS Interpretations Committee to interpret whether the discount rate to value environmental liabilities should be a risk-free discount rate. Old Canadian GAAP, and current U.S. GAAP, allow for a higher discount rate, resulting in commensurately lower liabilities. International regulators refused to address this issue expecting no diversity in practice in Canada. We investigate discount rate choices for a sample of Canadian oil and gas and mining firms and we show the expectation of no diversity in practice was wrong. Significant diversity in practice is evident: about one third of the sample firms choose a higher discount rate, avoiding a major increase in environmental liabilities on transition to IFRS. The evidence suggests that these firms had relatively larger environmental liabilities and that the discount rate decision is a strategic choice. The current diversity in practice in accounting for environmental liabilities is not acceptable as it is not consistent with the enhancing qualitative characteristic of comparability under the Conceptual Framework. Accounting regulators should act to create consistent and comparable reporting practice. Firms and managers facing larger environmental liabilities can choose to minimize environmental liabilities under IFRS, while it is the general public and society at large that bear the ultimate risk. The paper pushes forward the debate on whether recognised environmental liabilities should reflect the interests of equity investors, or if other investors and stakeholders should be taken into account.