32Our ability to map humanity's influence across Earth has evolved, thanks to powerful 33 computing, a network of earth observing satellites, and new bottom-up census and crowd-34 sourced data. Here, we provide the latest temporally inter-comparable maps of the terrestrial 35 Human Footprint, and assessment of change in human pressure at global, biome, and 36 ecoregional scales. In 2013, 42% of terrestrial Earth could be considered relatively free of 37 anthropogenic disturbance, and 25% could be classed as 'wilderness' (the least degraded end 38 of the human footprint spectrum). Between 2000 and 2013, 1.9 million km 2 -an area the size 39 of Mexico -of land relatively free of human disturbance became highly modified. The 40 majority of this occurred within tropical and subtropical grasslands, savannah, and shrubland 41 ecosystems, but the rainforests of Southeast Asia also underwent rapid modification. Our 42 results show that humanity's footprint is eroding Earth's last intact ecosystems, and greater 43 efforts are urgently needed to retain them. 44 45 Key words: Human pressure, cumulative pressure mapping, ecosystem degradation, human 46 modification, human footprint, wilderness, wild lands, biodiversity, conservation, land use 47 change. 48 3 Introduction 49Humans have influenced the terrestrial biosphere for millennia, converting much of Earth's 50 surface to anthropogenic land uses 1 . Nevertheless, there are still some ecosystems that remain 51 free from significant human pressure, thereby providing crucial habitats for imperilled 52 species 2,3 and maintaining the ecosystem processes that underpin planetary life-support 53 systems 4,5 . As a consequence, calls for the global identification, monitoring, and retention of 54 the remaining lands that are relatively free of direct anthropogenic disturbance are 55 increasing 6-8 .
56Over the past two decades, cumulative pressure maps that combine remotely-sensed 57 data with survey data are being increasingly used to assess the full range of human pressures 58 on land spatially 9 . These advances have facilitated the mapping of Earth's remaining marine 59 and terrestrial wilderness 8,10,11 , improved measures and estimates of species extinction risk 12 , 60 underpinned broader assessments of human impacts on ecosystems 13 and biodiversity [14][15][16] , 61 and enabled the identification of protected areas and world heritage sites in danger 14,17,18 . The 62 results of these mapping efforts are influencing global policy discussions 6,19 , and informing 63 on-the-ground decisions about where to undertake biodiversity conservation action [20][21][22] . 64 Here, we provide the latest global maps of cumulative human pressure 23,24 for the 65 years 2000, 2005, 2010, and 2013, and use them to assess how changes in human pressure are 66 altering Earth's terrestrial ecosystems. We used a human footprint threshold of <4 (on 0 -50 67 scale) to identify where land is considered ecologically intact (below the threshold) or highly 68 modified and thus ecologica...