Climate change, increasing human access, and conservation risk in the Arctic and Tropics
In the Arctic, warming is anticipated to increase accessibility of near-coastal and remote marine zones of all eight arctic nations, through loss and thinning of sea ice, by up to 28% by the middle of the 21st century, in addition to reducing traverse times of these zones over the same period [30]. The United States Navy estimates that a continued reduction of annual minimum sea ice extent will increase the navigability of arctic waters, resulting, over the next decade, in as many as 175 open-water days in the Bering Strait, and 45 open-water days in the Northern Sea Route and Transpolar Route [31]. By the middle of the 21st century, diminishing September sea ice extent is expected to increase substantially the frequency and feasibility of trans Arctic Ocean voyages for common open-water vessels [32]. Hence, shipping activity is expected to increase in offshore and remote marine zones across the Arctic, further increasing access to coastal regions and marine wildlife habitat. Simultaneously, expected temperature increases under IPCC Scenario A2 have the potential to affect habitat of species of conservation concern, such as the ivory gull (Pagophila eburnea), polar bear (Ursus maritimus), walrus (Odobenus rosmarus), and narwhal (Monodon monoceros) in southeastern Greenland; and ivory gulls, polar bears, and narwhal in northeastern Canada, where category I or II International Union for the Conservation of Nature (IUCN) protected areas are currently lacking (Figure 2A).
Moreover, current climatic conditions are expected to disappear under IPCC Scenario A2 over broad regions of northeastern Russia and the Canadian Arctic Archipelago and to disappear in several locations currently inhabited by the ivory gull, including within the Canadian Arctic Archipelago, Novaya Zemlya, the Svalbard Archipelago, and off the eastern coast of Greenland (Figure 2). In the Canadian Arctic Archipelago, there currently exist no protected areas under IUCN categories I, II, V, or VI within the zones of disappearing climates, and neither Greenland nor the Canadian Arctic Archipelago currently contains IUCN category Ia sites (Figure 2). The ivory gull is listed on the IUCN Red List as near-threatened and in severe decline [33]. The extremely limited distribution of this species, combined with the prospects for development of novel climatic conditions and disappearance of existing climatic conditions, together with the near absence of strictly protected areas throughout its distribution, signal the potential for elevated extinction risk to it. The inclusion of the beluga whale (Delphinapterus leucas) on the IUCN’s list of climate change flagship species also indicates that improved protected status is needed for areas within its distribution at risk of undergoing loss of current climatic conditions, such as the Russian and Canadian arctic archipelagos (Figure 2). As well, the IUCN Red List notes that the Pacific walrus subspecies may be at pronounced risk because of sea ice loss along coastal margins and due to increased human access to haul-outs in coastal areas [33]. The lack of IUCN protected areas in categories I and II along Alaska’s central arctic coast and along the entire arctic coast of Russia, where the probability of disappearance of current climatic conditions is highest, should be of particular concern with regard to this species, especially considering the potential for increased shipping activity as sea ice diminishes.
In the Tropics, climate change may exacerbate human pressure on remote forested regions already at risk of increased use for livestock farming and mineral extraction. Since the 1980s, forest buffers around 70% of 198 IUCN categories I and II areas, those with the highest conservation status, have declined due to deforestation, and 25% of IUCN categories I and II areas lost forest cover within their boundaries [34]. These losses were greatest in South America and Southeast Asia and occurred primarily in dry tropical forests [34], suggesting that drying due to warming in the Tropics may facilitate further deforestation. Road construction is also expected to be facilitated in the Tropics by warming and consequent drying and may, in turn, leave forest fragments additionally vulnerable to climate change [35]. Roads built for official infrastructure projects in the Tropics also catalyze the construction of unofficial roads, further exacerbating deforestation [35]. In Brazil, for instance, unofficial roads have expanded by a factor of four since 2001 and now account for more than 80% of the entire road network in the state of Pará [36]. In the southwestern Amazon alone, road building and associated land use is estimated to reduce forest cover and mammalian species diversity by 67% and 40%, respectively, by 2050 [35].
In the Southeast Asian tropics, regions of expected temperature increase over the next century under IPCC Scenario A2 display considerable overlap with the distribution of species such as the critically endangered Sumatran orangutan (Pongo abelii) and the endangered Malayan tapir (Tapirus indicus) on Sumatra (Figure 3A). The Sumatran orangutan, in particular, appears at great risk due to its extremely restricted distribution. Only three IUCN category Ia protected sites, with the highest level of biodiversity conservation, currently exist on Sumatra, with a single one of these within the distribution of the Sumatran orangutan. The Malayan tapir will likely also face increasing pressure because of the fragmented nature of its distribution combined with the lack of IUCN category I or II protected areas within its distribution on the Malay Peninsula, where temperature increases are also likely to be pronounced (Figure 3A). The scattered and fragmented distribution of tigers (Panthera tigris) in southeast Asia, together with a minimal distribution of protected areas, appears to be of greatest concern in Vietnam, Cambodia, and northeastern- and southwestern India, where temperature increases will be greatest (Figure 3A). Disappearance of current climatic conditions under IPCC Scenario A2 is most likely throughout Sumatra, the Malay Peninsula, and southern Vietnam and Cambodia, overlapping nearly completely the distributions of all three species in those regions (Figure 3B).
Among neotropical species, the greatest threats of expected temperature increases over the next century to species such as the endangered Baird’s tapir (Tapirus bairdii), Colombian woolly monkey (Lagothrix lugens), and the jaguar (Panthera onca) are likely to arise in northwestern Colombia, where only one IUCN category Ia site is currently found (Figure 3C). Jaguars may also be at risk in eastern Ecuador and northwestern Peru, where very few protected areas fall within the region of greatest expected temperature increase, only one of which is of IUCN category Ia (Figure 3C). Even greater risk to all three species may stem from the high likelihood of disappearance of current climatic conditions throughout the distributions of these species (Figure 3D). The Colombian woolly monkey is unique among these three species in the extent of IUCN category I or II protected areas within its distribution, while Baird’s tapir currently exists under the least protection throughout Central America (Figure 3C,D), where there are currently but five IUCN category Ia sites.
The current process of protected area assignment
The International Union for the Conservation of Nature (IUCN) has outlined a process of assignment of protected area status under guidelines that operate downward through a hierarchy of objectives. These begin with identification of management objectives, assessment of the site’s compatibility with the IUCN’s protected area criteria, and documentation of the site’s characteristics and justification for status as a protected area. Subsequently, a proposed management category is assigned for local governmental consideration [37]. The categories of IUCN protected areas range along a spectrum from strictest protection of biodiversity (category I) to sustainable management and human extraction permitted (category VI). Admittedly, the IUCN does foresee an increasing need to account for climate change impacts in this decision making process and the assignment of protected areas among these categories. However, this need is currently focused on such actions as species translocations, habitat management (which would necessitate increasing application of category IV assignments), and re-assignment of cultural landscapes currently under category V status to category I status as they become unsustainable for human use and are abandoned by humans in response to climate change [37]. Hence, the existing process of protected area assignment does not take into account the potential for habitat loss due to the interaction between climate change and increasing human land use, pressure, and wildlife exploitation.
We suggest that the IUCN’s adaptive decision making process will be improved by explicitly accounting for the risks posed by increased human access to remote wildlife habitat in regions of high endemism resulting from climate change, rather than solely from expectations of reduced human use. As described above, the Arctic and Tropics appear poised to develop novel climates and to lose existing climates, within the 21st century, resulting in loss of wildlife habitat. The development of novel climates may also, however, promote the suitability of wildlife habitat in areas that are currently unsuitable for some species and which therefore currently lack protected status. We recommend that the IUCN and conservation ecologists engage more directly with geophysicists, geographers, and climate scientists to improve understanding of the complex interactions among disappearance or evolution of climates, resultant changes in human access to remote areas, and consequent erosion of existing—or development of new—wildlife habitat. Consultation with social scientists, with expertise on local cultural perspectives and how these may or may not shift in response to changing access to remote regions with climate change, is also highly recommended.
Implementing measures to elevate the status of existing protected areas, and to establish new ones, may prove to be an essential component of wildlife conservation in anticipation of climate change. In tropical West Africa, for instance, it is estimated that elevating the status of 12 of 16 existing key biodiversity areas to IUCN category I–IV sites would enhance the protection of 13 of 14 threatened species of large mammals endemic to that region [38]. We also focus here primarily on mammals of cultural and conservation interest in the Arctic and Tropics. Human access to remote areas in both regions is expected to be highly responsive to climate change, and mammals worldwide exhibit high rates of endemism [39]. Furthermore, large mammals are at greatest risk among the 20% of extant species considered vulnerable to extinction [40].