Efforts to conserve biodiversity comprise a patchwork of international goals, national-level plans, and local interventions that, overall, are failing. We discuss the potential utility of applying the mitigation hierarchy, widely used during economic development activities, to all negative human impacts on biodiversity. Evaluating all biodiversity losses and gains through the mitigation hierarchy could help prioritize consideration of conservation goals and drive the empirical evaluation of conservation investments through the explicit consideration of counterfactual trends and ecosystem dynamics across scales. We explore the challenges in using this framework to achieve global conservation goals, including operationalization and monitoring and compliance, and we discuss solutions and research priorities. The mitigation hierarchy's conceptual power and ability to clarify thinking could provide the step change needed to integrate the multiple elements of conservation goals and interventions in order to achieve successful biodiversity outcomes.

As human activities increasingly threaten biodiversity [1, 2], areas devoid of intense human impacts are vital refugia [3]. These wilderness areas contain high genetic diversity, unique functional traits, and endemic species [4-7]; maintain high levels of ecological and evolutionary connectivity [8-10]; and may be well placed to resist and recover from the impacts of climate change [11-13]. On land, rapid declines in wilderness [3] have led to urgent calls for its protection [3, 14]. In contrast, little is known about the extent and protection of marine wilderness [4, 5]. Here we systematically map marine wilderness globally by identifying areas that have both very little impact (lowest 10%) from 15 anthropogenic stressors and also a very low combined cumulative impact from these stressors. We discover that ∼13% of the ocean meets this definition of global wilderness, with most being located in the high seas. Recognizing that human influence differs across ocean regions, we repeat the analysis within each of the 16 ocean realms [15]. Realm-specific wilderness extent varies considerably, with >16 million km (8.6%) in the Warm Indo-Pacific, down to <2,000 km (0.5%) in Temperate Southern Africa. We also show that the marine protected area estate holds only 4.9% of global wilderness and 4.1% of realm-specific wilderness, very little of which is in biodiverse ecosystems such as coral reefs. Proactive retention of marine wilderness should now be incorporated into global strategies aimed at conserving biodiversity and ensuring that large-scale ecological and evolutionary processes continue. VIDEO ABSTRACT.

Due to an error during the production of this article, the first row of data in Table 1 was inadvertently omitted. This row should have read as follows: ''Arctic (8,740,149) j 4,024,686 (46.0) j 282,050 (7) j 868,845 (9.9) j 63,406 (7.3).'' The table has now been corrected in the article online. The journal apologizes for the error and any confusion it may have caused.

As human activities increasingly threaten biodiversity [ 1 , 2 ], areas devoid of intense human impacts are vital refugia [ 3 ]. These wilderness areas contain high genetic diversity, unique functional traits, and endemic species [ 4 , 5 , 6 , 7 ]; maintain high levels of ecological and evolutionary connectivity [ 8 , 9 , 10 ]; and may be well placed to resist and recover from the impacts of climate change [ 11 , 12 , 13 ]. On land, rapid declines in wilderness [ 3 ] have led to urgent calls for its protection [ 3 , 14 ]. In contrast, little is known about the extent and protection of marine wilderness [ 4 , 5 ]. Here we systematically map marine wilderness globally by identifying areas that have both very little impact (lowest 10%) from 15 anthropogenic stressors and also a very low combined cumulative impact from these stressors. We discover that ∼13% of the ocean meets this definition of global wilderness, with most being located in the high seas. Recognizing that human influence differs across ocean regions, we repeat the analysis within each of the 16 ocean realms [ 15 ]. Realm-specific wilderness extent varies considerably, with &gt;16 million km 2 (8.6%) in the Warm Indo-Pacific, down to &lt;2,000 km 2 (0.5%) in Temperate Southern Africa. We also show that the marine protected area estate holds only 4.9% of global wilderness and 4.1% of realm-specific wilderness, very little of which is in biodiverse ecosystems such as coral reefs. Proactive retention of marine wilderness should now be incorporated into global strategies aimed at conserving biodiversity and ensuring that large-scale ecological and evolutionary processes continue.

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