Hesketh, P 2026, 'Determining the vulnerability of asset retirement obligations across the mining sector', in AB Fourie, G Boggs, J Heyes & M Tibbett (eds), Mine Closure 2026: Proceedings of the 19th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1-10, https://doi.org/10.36487/ACG_repo/2615_37
(https://papers.acg.uwa.edu.au/p/2615_37_Hesketh/)
Abstract: Asset retirement obligations (AROs) detail the corporate liability associated with decommissioning and environmental rehabilitation across a corporate portfolio, i.e. they represent the committed cost of closure across the whole company. An ARO is effectively a debt on a company’s balance sheet as the accounting treatment provides a single aggregated number that is discounted for future spend. AROs are opaque, and it is difficult for investors to understand the potential impact of cost increases and non-discretionary annual spending commitments, and consequently the risks that sit within investment portfolios. AROs for major mining organisations have increased substantially, with 11 miners reporting a combined USD 36.2 billion increase between 2015 and 2024, amounting to an 8% year-on-year increase despite individual annual spend of up to USD 1.1 billion (Rio Tinto 2024).
The long-term nature of AROs, with a cost horizon typically exceeding 15 years at the corporate level, places them outside the interest of ratings agencies, which are more concerned with risks within a shorter time frame (<5 years).
ARO vulnerability assesses the potential for cost escalation at the portfolio level. The assessment involves unravelling the ARO to determine the probable total cost of closure at a corporate level and then an assessment of causative factors within the portfolios which would be likely to increase closure costs over the life of the assets within the portfolio. It provides a tool to address corporate closure performance by heightening investor knowledge, enabling modelling of closure impacts on investor portfolios and feeding into a closure/transition mark.