Global human influence maps reveal clear opportunities in conserving Earth’s remaining intact terrestrial ecosystems

Abstract

Leading up to the Convention on Biological Diversity Conference of the Parties 15, there is momentum around setting bold conservation targets. Yet, it remains unclear how much of Earth's land area remains without significant human influence and where this land is located. We compare four recent global maps of human influences across Earth's land, Anthromes, Global Human Modification, Human Footprint and Low Impact Areas, to answer these questions. Despite using various methodologies and data, these different spatial assessments independently estimate similar percentages of the Earth's terrestrial surface as having very low (20%–34%) and low (48%–56%) human influence. Three out of four spatial assessments agree on 46% of the non‐permanent ice‐ or snow‐covered land as having low human influence. However, much of the very low and low influence portions of the planet are comprised of cold (e.g., boreal forests, montane grasslands and tundra) or arid (e.g., deserts) landscapes. Only four biomes (boreal forests, deserts, temperate coniferous forests and tundra) have a majority of datasets agreeing that at least half of their area has very low human influence. More concerning, <1% of temperate grasslands, tropical coniferous forests and tropical dry forests have very low human influence across most datasets, and tropical grasslands, mangroves and montane grasslands also have <1% of land identified as very low influence across all datasets. These findings suggest that about half of Earth's terrestrial surface has relatively low human influence and offers opportunities for proactive conservation actions to retain the last intact ecosystems on the planet. However, though the relative abundance of ecosystem areas with low human influence varies widely by biome, conserving these last intact areas should be a high priority before they are completely lost.

Earth transformed: detailed mapping of global human modification from 1990 to 2017

“…The biggest differences in rankings between the H and the HF were for temperate and broadleaf mixed forests (and see comparisons of H1k and the HF in Kennedy et al, 2019b, c;Riggio et al, 2020). The HF was estimated to result in a 12.3 % modification for an earlier date Venter et al, 2016) and is lower likely because fewer stressors were included, because of its additive combination method, and because of its strongly right-skewed distribution caused by max-value normalization.…”

“…Importantly, F and I have a direct physical interpretation (Gardner and Urban, 2007), are well bounded, and range from 0 to 1 and values are a "real" data type. Consequently, H provides the basis for unambiguous interpretation to assess landscape change (Hajkowicz and Collins, 2007;Riitters et al, 2009). Specific formulas used to map raw stressor data as indicator layers are provided below.…”

“…Terrestrial lands with very low levels of human modification (H < 0.01; Kennedy et al, 2019a;Riggio et al, 2020) are concentrated in less productive and more remote areas in high latitudes and are dominated by inaccessible permanent rock and ice or are within tundra, boreal forests, desert regions, and to a lesser extent montane grasslands. Table 5 shows that the biomes with the highest levels of H in ∼ 2017 were temperate broadleaf and mixed forests (H = 0.3744); tropical and subtropical dry broadleaf forests (H = 0.3317); and Mediterranean forests, woodlands and scrub (H = 0.2903).…”

“…A summary of the data, methods, and results comparing the degree of human modification (HM; this paper), degree of human modification 1 km (HM1k; Kennedy et al, 2019a, b, c), human footprint (HF; Sanderson et al, 2002;Venter et al, 2016), and temporal human pressure index (THPI;Geldmann et al, 2019b). Also see discussion of comparison in Kennedy et al (2019a, c), Venter et al (2019), and Riggio et al (2020). Data source acronyms are provided in Table 1. Factor HM HM1k HF THPI…”

A machine-learning approach to human footprint index estimation with applications to sustainable development

“…The human footprint index (HFI) represents one of the most important tools for interpreting human pressure on the landscape (1) . A dimensionless metric which captures the extent of human influence on the terrestrial surface, the HFI is distinct from many land-use metrics in that it captures the total influence of human existence on a given location in a single index, rather than categorizing individual land use types (2) . The applications to which the HFI is put to use are manifold (3)(4)(5)(6) , with enormous demand for information about human pressure on the land surface to support policies related to land use change, biodiversity conservation, and climate action (6)(7)(8) .…”