A study analyzing over 160,000 protected areas (PAs) globally reveals that while PAs are effective in reducing habitat loss compared to unprotected areas, their overall effectiveness varies significantly. The research, using high-resolution satellite data, found that 1.14 million km² of habitat, equivalent to three times the size of Japan, was altered between 2003 and 2019. Larger and stricter PAs generally had lower rates of habitat loss, but most PAs were less effective in preventing deforestation and agricultural conversion. PAs were 33% more effective in reducing habitat loss than unprotected areas, but their ability to mitigate nearby human pressures varied spatially. The study highlights that habitat loss within PAs is driven by urbanization, cropland expansion, pastureland conversion, and deforestation. While PAs in regions like the Amazon and Europe showed some effectiveness, many PAs, especially smaller ones, were less effective. The effectiveness of PAs also depends on factors such as governance type, biodiversity importance, and distance from cities. The research emphasizes the need to improve the effectiveness of existing PAs rather than just expanding them to achieve global biodiversity goals. The study also found that PAs have a time lag in their effectiveness, with some effects taking up to six years to manifest. This suggests that the establishment of PAs does not immediately reduce habitat loss and that long-term management and monitoring are crucial. The findings indicate that PAs in certain regions, such as the Amazon Basin, are more effective in curbing habitat loss, while others, like parts of Africa and Europe, are less effective. The study calls for targeted strategies to enhance the effectiveness of PAs, considering their specific locations and characteristics. Overall, the research underscores the importance of improving the performance of existing PAs to better protect biodiversity and achieve the 30×30 global conservation targets.A study analyzing over 160,000 protected areas (PAs) globally reveals that while PAs are effective in reducing habitat loss compared to unprotected areas, their overall effectiveness varies significantly. The research, using high-resolution satellite data, found that 1.14 million km² of habitat, equivalent to three times the size of Japan, was altered between 2003 and 2019. Larger and stricter PAs generally had lower rates of habitat loss, but most PAs were less effective in preventing deforestation and agricultural conversion. PAs were 33% more effective in reducing habitat loss than unprotected areas, but their ability to mitigate nearby human pressures varied spatially. The study highlights that habitat loss within PAs is driven by urbanization, cropland expansion, pastureland conversion, and deforestation. While PAs in regions like the Amazon and Europe showed some effectiveness, many PAs, especially smaller ones, were less effective. The effectiveness of PAs also depends on factors such as governance type, biodiversity importance, and distance from cities. The research emphasizes the need to improve the effectiveness of existing PAs rather than just expanding them to achieve global biodiversity goals. The study also found that PAs have a time lag in their effectiveness, with some effects taking up to six years to manifest. This suggests that the establishment of PAs does not immediately reduce habitat loss and that long-term management and monitoring are crucial. The findings indicate that PAs in certain regions, such as the Amazon Basin, are more effective in curbing habitat loss, while others, like parts of Africa and Europe, are less effective. The study calls for targeted strategies to enhance the effectiveness of PAs, considering their specific locations and characteristics. Overall, the research underscores the importance of improving the performance of existing PAs to better protect biodiversity and achieve the 30×30 global conservation targets.