Gains in biodiversity conservation and ecosystem services from the expansion of the planet's protected areas

Abstract

Protected areas safeguard biodiversity, ensure ecosystem functioning, and deliver ecosystem services to communities. However, only ~16% of the world's land area is under some form of protection, prompting international calls to protect at least 30% by 2030. We modeled the outcomes of achieving this 30 × 30 target for terrestrial biodiversity conservation, climate change mitigation, and nutrient regulation. We find that the additional ~2.8 million ha of habitat that would be protected would benefit 1134 ± 175 vertebrate species whose habitats currently lack any form of protection, as well as contribute to either avoided carbon emissions or carbon dioxide sequestration, equivalent to 10.9 ± 3.6 GtCO₂ year^-1 (28.4 ± 9.4% of the global nature-based climate-change mitigation potential). Furthermore, expansion of the protected area network would increase its ability to regulate water quality and mitigate nutrient pollution by 142.5 ± 31.0 MtN year^-1 (28.5 ± 6.2% of the global nutrient regulation potential).

Fig. 1.. Magnitude of additional biodiversity conservation, climate-change mitigation, and nutrient-regulation benefits associated with protecting 30% of terrestrial areas in 193 countries globally, across nine scenarios.

Insets indicate the total potential benefits within each region’s boundaries across a specific area, with values representing average and 95% confidence intervals (calculated on the basis of all nine modeled scenarios).

Fig. 2.. Relative magnitude of climate-change mitigation and nutrient-regulation benefits across each country, and the relative magnitude of these benefits in relation to the area of expansion needed to achieve the 30% target.

Countries (points) are color-coded by region and point size denotes the relative degree of biodiversity conservation benefits.

Fig. 3.. Effect of increasing protected area coverage on the relative magnitude of biodiversity conservation, climate-change mitigation, and nutrient-regulation benefits.

All protected area coverage targets considered are compared to the initial 30% target. Dots indicate the average values across all nine modeled objectives, while uncertainty (lines) represents 95% confidence intervals.