As biodiversity loss and climate change become increasingly intertwined, expanding protected areas is no longer simply a question of how much land and sea to protect. It also matters which species and ecological functions are protected, whether ecological connectivity can be maintained, how costly conservation is, and how fairly countries share responsibilities.
In a study published in Nature Communications, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences, and their collaborators showed that expanding protected areas to 30% or 50% is not enough. Global conservation must also prioritize species representation, carbon storage, ecological connectivity, cost, and equitable responsibility-sharing.
The researchers examined global protected-area expansion under “30 by 30,” Target 3 of the Global Biodiversity Framework, which aims to protect at least 30% of terrestrial and marine areas by 2030, and “50 by 50,” the “Half Earth” vision of protecting 50% of the planet. They assessed these strategies under near-current and future climates, focusing on effectiveness, connectivity, cost-efficiency, and equity.
The researchers quantitatively evaluated the performance of different conservation strategies in terms of effectiveness (the proportion of global species richness and carbon stocks covered), ecological connectivity, and cost-efficiency by integrating two core indicators: species diversity (including plants, amphibians, birds, mammals, and reptiles) and carbon storage.
They found that meeting the 30 by 30 target would require an additional 1,889 million hectares of land, while a “50 by 50” scenario would require about 4.581 billion hectares. However, area expansion alone will not automatically improve conservation quality; new protected areas must complement existing networks by filling spatial mismatches in species, carbon storage, and protection coverage.
Furthermore, multi-objective strategies entail a relatively small loss of connectivity in exchange for more balanced conservation benefits and lower costs. Such strategies must be coordinated with land-use policies and expanded gradually from priority areas adjacent to existing protected areas, maintaining and restoring ecological connectivity while reducing land-use conflicts.
The study emphasized the need to rebalance responsibility-sharing between the Global North and the Global South, suggesting financial support or compensation mechanisms to alleviate the burdens on low-income countries. This would improve the affordability of conservation measures and provide equity-related guidance for implementing the Kunming-Montreal Global Biodiversity Framework and the Paris Agreement.
The researchers suggested that future efforts should employ dynamic optimization models to integrate climate change projections, land-use threats, and species distribution data, prioritize filling protection gaps, and reduce redundant conservation efforts by applying complementarity principles.
Contact
BAI Yang, Ph.D., Principal Investigator
Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences
E-mail: baiyang@xtbg.ac.cn
Published: 05 August 2026
