The role of protected areas in mitigating human impact in the world's last wilderness areas.

Human impact on the environment is evident across the planet, including its most biodiverse areas. Of particular interest is the impact on the world's last wilderness areas, in which the largest patches of land relatively free from human influence remain. Here, we use the human footprint index to measure the extent to which the world's last wilderness areas have been impacted by human activities-between the years 1993 and 2009-and whether protected areas have been effective in reducing human impact. We found that overall the increase in human footprint was higher in tropical than temperate regions. Moreover, although on average the increase was lower inside protected areas than outside, in half of the fourteen biomes examined the differences were insignificant. Although reasons varied, protected areas alone are unlikely to be ubiquitously successful in protecting wilderness areas. To achieve protection, it is important to address loss and improve environmental governance.