Introduction

The mining and metals industry and sustainable development are closely interlinked, as the extraction and production of raw materials can negatively affect local ecosystems, global warming, and human health. Conversely, responsible mining and metal production contribute to achieving Sustainable Development Goals, including responsible consumption and production. Metals such as copper, nickel, cobalt, and lithium are essential for the global energy transition and decarbonisation. To measure environmental impacts along supply chains, Carbon Footprint and Life Cycle Assessment (LCA) methods are widely used. However, methodological flexibility in existing standards has led to inconsistent results, prompting the International Council on Mining and Metals (ICMM) to develop harmonised methodological recommendations.

Methods

The development of recommendations for calculating the Product Carbon Footprint (PCF) and LCA of metals was achieved through a three-step process. This included a criteria-based comparison of existing standards, expert interviews, and the development of an updated harmonised approach. The research aimed to update the 2016 framework, harmonise metal PCF and LCA results, and increase consistency with rules developed by industry initiatives and legislation.

Criteria-based comparison

The study reviewed existing PCF guidelines from various metal organisations, international standards, and industry initiatives. These documents were compared by juxtaposing their requirements across 17 methodological aspects. The review refers to the latest versions of these documents available in September 2025. This comparison served to determine the specific methodological parameters that required guidance and further harmonisation within the industry.

Expert interviews

Nine experts from metal organisations and consultancies were interviewed to discuss key methodological aspects decisive for metal PCF and LCA results. The focus was on allocation procedures in the mining, concentration, smelting, and refinery stages, as well as the handling of pre- and post-consumer scrap. These interviews were used to understand modelling choices and identify potential options for reaching a consensus.

Development of a harmonised PCF and LCA approach

A consensus-finding process was conducted in close cooperation with ICMM and a project steering group. Proposals to harmonise the way of modelling were discussed in online workshops between July 2023 and October 2024. The recommendations were developed to specify generic requirements for the mining and metals industry while leaving sufficient flexibility for metal-specific guidelines to reflect individual production routes.

Results & discussion

The analysis identified high levels of consistency in aspects such as the functional unit (1 kg of metal), system boundaries (cradle-to-gate), and data sources. Moderate consistency was found in cut-off criteria, electricity modelling, and update cycles. Lower consistency was noted in multi-output allocation and recycling allocation. It was determined that PCF studies conducted in line with the provided recommendations will largely fulfil the requirements of other international standards.

Criteria-based comparison and interviews

Results from the comparison matrix show that most metal PCF guidelines define a cut-off criterion as below 1% of total greenhouse gas emissions, not exceeding 3% cumulatively. Differences were identified regarding the greenhouse gases included in the analysis and allocation methods in smelting and refinery stages. For example, most guidelines recommend including the gases for which the IPCC’s sixth assessment report provides GWP100 factors, whereas the worldsteel guide requires measuring carbon dioxide emissions only as a minimum.

Harmonised PCF and LCA guidelines

Specific recommendations were developed for 17 methodological aspects. The functional unit is defined as 1 kg of metal or precursor product. System boundaries are set as cradle-to-gate, encompassing the entire supply chain from mining to refinery. Electricity modelling requires dual reporting of both location-based and market-based methods. Allocation follows a strict hierarchy, preferring physical relationships like the mass of extracted metal content. Economic allocation is preferred if physical relationships cannot be established or if the price-difference factor between co-products exceeds 4 or 5. For recycling, a closed-loop approach is recommended for pre-consumer scrap if material properties remain unchanged.

Consistency of updated recommendations with other PCF and LCA guidelines

The updated recommendations reach a high degree of consistency with relevant industry initiatives such as PACT, Catena-X, and the Global Battery Alliance. Studies conducted according to these recommendations will fulfil the requirements of other standards because they are often more specific or stricter. For example, while other guidelines define data quality quantitatively, these recommendations require a quantitative data quality rating and primary data shares.

Conclusions & recommendations

Harmonised recommendations for key methodological aspects in PCF and LCA have been developed for the mining and metals industry. While high consistency was achieved in defining functional units and system boundaries, allocation and electricity modelling remain complex areas that would benefit from further harmonisation. Calculating results according to these recommendations will enable a large degree of consistency with international standards and industry initiatives.