Can humanity have its cake and eat it too?

Project Details

Key Questions

How to mitigate human impacts on biodiversity in order to meet international conservation targets


This project investigates how to mitigate human impacts on biodiversity, in a world where there are competing social priorities and biodiversity is declining as a result of our actions. Governments around the world have committed to conserving and restoring nature, but it is not clear how to implement these commitments in practice. In partnership with a leading international business, Balfour Beatty, the student will use the mitigation hierarchy approach to calculate the global room for manoeuvre that would allow biodiversity goals to be met in the context of sustainable development

Aims of the Project

i) Provide spatially explicit estimates of the scope for avoidance of human impact and ecosystem restoration and ‘net gains’ at a large scale, and put this in the context of international aspirations for biodiversity conservation?

ii) For a case study landscape, explore the combinations of measures that could fulfil biodiversity conservation goals, in the context of the government’s development aims for the landscape.

iii) For a case study business, explore the combination of measures that would lead to landscape-level net gains in biodiversity that directly contribute towards CBD targets, in the context of wider trends.

iv) Develop a method for integrating sectoral, landscape and threat-based approaches to estimating the biodiversity mitigation required to meet the CBD’s targets, in order to implement the mitigation hierarchy.

Project Description

Over the next two years the world will be analysing progress towards the Convention on Biological Diversity’s (CBD) Aichi Targets, learning lessons from their success and failures and planning for the next phase of the CBD’s 2050 Vision. Reflecting the widescale threats to biodiversity, there are calls for new ambitious visions and targets such as ‘Nature Needs Half’. There is much less consideration, however, of how these targets will be operationalised. It is currently unclear how to translate international targets into strategies that can be implemented at the national, sector and project levels, or reported back up to global-level assessments of progress, which then feed back to inform conservation action.

Another barrier is the lack of integration of biodiversity targets into the master-planning of economic development projects. These projects are usually planned without consideration of how the development can underpin and support international, national and local biodiversity targets. Instead biodiversity considerations come far later in a project lifecycle, when it is much harder and sometimes too late to effect positive change and the only option is to minimise the damage.  This exacerbates the ‘development versus nature’ mind-set, whereas linking development plans with biodiversity targets at the start can go a long way to ensuring that development is a major driver of conserving and enhancing biodiversity.

The Mitigation Hierarchy is no longer only used to mitigate negative impacts, but a process whereby maintaining and enhancing biodiversity is considered at each stage, for example international best practice guidelines call for Impact Assessments to maintain and enhance biodiversity. There is also a movement within industry towards ‘Biodiversity Net Gain’ (BNG) outcomes. But BNG is voluntary in many countries, and is typically planned for individual projects in isolation of other developments within the landscape. There is also often little or no connection between BNG and strategic biodiversity targets, leading to missed opportunities.

There are multiple barriers to achieving the scalability and interplay of action and reporting needed, in particular because biodiversity loss is driven by a range of simultaneously occurring processes that span borders and sectors, many of which are undocumented and unregulated. Effective action to halt biodiversity loss must therefore be similarly wide ranging and multi-sectoral, guided by a clear and robust framework.

Recent research in E.J. Milner-Gulland’s group has proposed such a framework; the Global Mitigation Hierarchy (Arlidge et al. 2018).  This takes the mitigation hierarchy, a well-established approach for reducing impacts to biodiversity at a project level, and applies it as an overarching framework for considering impacts against a target at a sector, national or global level. The global mitigation hierarchy (GMH) provides a vehicle for assessing and reporting how biodiversity is impacted (both positively and negatively) by human activity. It is applied sequentially in four steps going from avoidance to compensatory actions: avoid impacts where possible; minimise unavoidable impacts; restore impacted biodiversity; and offset residual impacts. Protected areas are an example of the avoidance step, whilst technological improvements to fishing gears to reduce non-target species captures are an example of minimisation. Restoration is widely practiced (for example Brazil’s commitment to reforesting 12 million ha of land by 2030), while offsetting includes conservation action for components of biodiversity not affected by the impact.

Using the GMH to structure assessment of progress towards halting biodiversity loss would provide a scalable framework to integrate all types of conservation action into one assessment; something which is currently not possible. This would then enable governments, businesses, investors, international institutions and conservation actors to plan effective management regimes which enable them both to meet, and report progress against, global targets. This would result in more explicit consideration of humanity’s capacity to conserve different components of biodiversity. It would guide the consideration of key issues such as identifying the scope which remains for avoidance within an area, country or ecoregion, priorities for minimisation of biodiversity impacts, and where restoration and offsetting can and should occur. It would explicitly prioritise avoidance over compensation, seek No Net Loss and Net Gain at each stage of the Mitigation Hierarchy (not just at the end) and leave space for innovation and least-cost methods at each step of the hierarchy.

This novel usage of the hierarchy has been explored conceptually but the next stage is to test its application as an approach to operationalising targets for the post-2020 biodiversity agenda. Currently a pilot project is being carried out to start this assessment, and this PhD position would build on that foundation to provide the concrete empirical evidence on how the GMH would work in practice, as well as working with business and other stakeholders to bring it into practical usage. This is an ambitious and exciting project that would enable a student to carry out research at the cutting edge of the global biodiversity agenda.

Reference: Arlidge, W., Bull, J., Addison, P., Burgass, M., Gianuca, D., Gorham, T., Jacob, C., Lloyd, S., Shumway, N., Watson, J., Wilcox, C., Milner-Gulland, E.J. (2018) A global mitigation hierarchy for nature conservation. Bioscience 68 336-347

Methods to be used

GIS and mapping, and collation of a range of publically available biodiversity datasets
Systematic conservation planning
Decision analysis
Systems analysis

Specialised skills required

Being able to think in a creative and novel way about challenging and complex systems

Being able to work effectively with a wide range of stakeholder groups, with a “can-do” and open-minded attitude


Please contact EJ Milner Gulland on if you are interested in this project