Fig. 6: Potential and unrealistic conservation gains for terrestrial and marine vertebrates.

We define as low vs. high conservation gains (x-axis) the bottom vs. top-ranked (10%) unprotected areas for the conservation of vertebrates according to the maximisation of species range size coverage on land (a birds and mammals) and sea (b fish). We define as potential vs. unrealistic conservation gains (y-axis), the unprotected areas being the most likely (‘low-hanging fruits’) vs. unlikely (‘high-hanging fruits’) to be protected according to their social-environmental context. On global maps, established protected areas are in green, while we only represent the potential vs. unrealistic high conservation gains on land (c) and sea (d). The gradient of colours corresponds to the relative likelihood that these unprotected areas are turned into protected areas according to the 14 social-environmental factors (Tables 1 and 2) and Random Forest models (see ‘Methods’). So, potential high conservation gains are in dark blue, while unrealistic high gains are in dark red. See Fig. 5 for the average relative likelihood of PA establishment per country on land and sea. These patterns could be biased by missing PAs in the Word Database on Protected Areas. Source data and codes are provided at https://doi.org/10.5281/zenodo.11183846.