International Association for Impact Assessment

Three reasons why the mitigation hierarchy matters to impact assessment

  • Guest post by Board member Sara Bice

    Three reasons why the mitigation hierarchy matters to impact assessment

    Three reasons why the mitigation hierarchy matters to impact assessment

    Sara Bice

    As an impact assessor who usually hangs around the social end of the practice spectrum, I came to the IAIA’s recent symposium on ‘Mainstreaming the Mitigation Hierarchy’ interested but unfamiliar. This seems ironic in hindsight, given societies’ fundamental reliance on biodiversity and ecosystems.

    The mitigation hierarchy first emerged in the US in the ‘70s and now underpins the International Finance Corporation’s Performance Standard 6 on Biodiversity Conservation and Sustainable Management of Living Natural Resources. It aims to assist in the management of biodiversity risk and provides an important reference point for managing environmental and social risks. The hierarchy prioritises avoidance before moving to efforts to minimise impacts, restore damaged ecosystems and finally offset residual damage. Following this sequence is seen as necessary to improve outcomes for biodiversity, ecosystems and the services they provide. Although its potential is great, recent studies and practice suggest that the mitigation hierarchy is underutilised. 

    IAIA’s two-day forum in Washington, DC, tackled this situation, focusing on how to ‘mainstream’ the mitigation hierarchy in IA practice to improve outcomes for biodiversity. Participating organisations, including the IUCN, argued that the hierarchy has much to offer impact assessors of all stripes. The foresight and leadership of IAIA in identifying this as a critical trend is to be applauded.

    So, for those who weren’t there, what can we learn from the experts pursuing the mainstreaming of the mitigation hierarchy? Here are three things I took away.

    1) The mitigation hierarchy can contribute to a social licence to operate

    In recent years, social impact assessment has turned much attention to a social licence to operate (SLO). The mitigation hierarchy concentrates corporate attention on the complexity of their environmental impacts. While certain corporate critics have argued that the mitigation hierarchy may inhibit growth, those supportive of mainstreaming the hierarchy assert that attention to it reduces negative environmental risk and, by extension, social backlash.

    For the International Finance Corporation, the connection between the mitigation hierarchy and broader, environmental, social and governance concerns is explicit in what they are calling ‘IFC 3.0’. This third iteration of the Social and Environmental Performance Standards speaks directly to the UN’s Sustainable Development Goals, making broader connections between the mitigation hierarchy (and other components of the Standards) and broader social concerns.

    Attention to these issues is also shaping the IFC’s advisory services to investors, including the World Bank. Here, there is a particular aim to focus attention on non-technical risks and, by extension, to improve strategic focus. The mitigation hierarchy has a critical role to play in this strategic process.

    2) Do no harm

    The mitigation hierarchy brings strong focus to the precautionary principle to emphasise a ‘do no harm’ approach. In so doing, it is encouraging funders, corporates and impact assessment practitioners to address the challenges of measuring relationships within ecosystems. While ecosystem assessment is not new, many of these relationships have historically been perceived as intangible and, therefore, lack indicators and measurement. The challenges faced by our environmental colleagues – in terms of setting baselines and measuring the unmeasured echoes longstanding challenges in social impact assessment.

    Partly in an effort to make ‘do no harm’ a more measureable (and arguably more meaningful) benchmark, the IFC is focused on developing common diagnostic tools. Ideally, such tools would allow for stronger comparison across organisations like the IFC and World Bank, while bolstering more strategic decision-making, especially with an upstream outlook for projects.

    3) Who decides?

    Biodiversity and ecosystems experts face similar questions to their SIA colleagues in relation to who decides what matters, who can be an expert and who holds the power to set benchmarks. The questions of ‘who can know?’ and ‘who decides?’ are especially vital in an era in which trust in expertise is in decline at the same time that peer-to-peer influence is on the rise.

    How can community views be better incorporated into decisions about biodiversity?

    And what steps can be taken to ensure that data will be trusted, and therefore, used and valued?

    These three issues emerging as critical for biodiversity and ecosystem assessors can remind us all of the importance of a social licence, the precautionary principle and issues of power, trust and inclusion across all types of impact assessment. They also remind us of the inextricably interconnected ecosystems of impact assessment.

    Regardless of individual expertise or assessment focus, we are all contributing to the same goal, working with the same fragile materials. As Conservation International’s Marielle Carter-Weikel stated in the Symposium’s opening plenary, ‘If we are eroding natural capital, we’re undermining the building blocks of economies and societies.’ All the more reason for impact assessors of all stripes to consider the relevance and potential for mainstreaming the mitigation hierarchy.    

    Comment on IAIAConnect, share on LinkedIn (IAIA discussion group), Tweet (@IAimpact) or email us ( We’d love to hear your ideas.


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