Adaptation strategies were developed for 20 large-scale conservation projects from North America, Central America, South America, Asia, and the Pacific Islands (Table 1). Projects’ areas ranged from 24,000 hectares (Chongming Dongtan Estuary, China) to more than 200 million hectares (Western Arctic, Alaska, USA and Canada). Projects spanned a diversity of habitats from large marine systems to coastal estuaries, lakes and rivers, forests, grasslands, aridlands, and montane and alpine ecosystems. While there was an emphasis on habitats and ecosystems in this analysis, six projects also targeted one or more individual species when considering climate impacts or developing adaptation strategies.
We report on three groups of findings from this effort: (1) the character of specific climate change impacts identified by the project teams (i.e., Table 2, Step 2—Formulate specific ecological “hypotheses of change”); (2) anticipated changes to the projects’ focal ecosystems and species as a result of these collective impacts (i.e., Table 2, Step 5—Evaluate if potential climate impacts fundamentally change the project); and (3) the objectives and actions of climate adaptation strategies to address the potential impacts (i.e., Table 2, Step 6—Develop adaptation strategies and evaluate their feasibility and cost).
Climate change impacts
Project teams identified 139 potential climate change impacts that are likely to affect ecosystems or species in their project area (See Supplementary Table 1). For example, the project team working on the Altamaha-Ogeechee Estuarine Complex identified sea-level rise as a potential cause of coastal habitat loss, and the project team for the Tallgrass Aspen Parkland identified increasing summer temperatures as a potential cause of moose mortality because of heat stress. On average, project teams identified between five and six climate impacts to their project; the minimum was three (Altamaha-Ogeechee Estuarine Complex, USA) and maximum was eight (Atitlán Watershed, Guatemala and Atlantic Forest, Brazil). We classified each of these potential impacts into one or more of a dozen logical categories (Table 3). We also classified them according to the underlying climate factor (e.g., temperature change, precipitation change) (Table 4). Some potential impacts were appropriately placed into more than one category and so the total number of classified impacts was 176 and the total number of classified climate factors was 186. An example of such a dual impact was warmer, drier conditions in the Atlantic Forests of Brazil leading to increased fire frequency and associated habitat degradation—we classified the impact as pertaining to both fire regime and habitat loss, and the climate factor as both change in temperature and change in precipitation.
Habitat loss and changes in habitat conditions were the most and fourth-most cited climate impacts, respectively, constituting 48 (27%) of all climate impacts identified by project teams (Table 3). For example, rising temperatures were expected to diminish sea ice habitat in the Arctic and cause coral die-backs, and sea-level rise was expected to inundate coastal habitats. Changes to hydrologic regimes was the second-most cited climate impact, identified 27 times (15%). The least cited climate impact was habitat fragmentation (only 5 citations, 3%).
Among the 20 projects, approximately three-quarters of anticipated climate impacts are expected to manifest in ways that are exacerbations of traditional threats—e.g., habitat loss and degradation, altered fire or hydrologic regimes. Novel impacts included shifting ranges (e.g., increased semi-deciduous forest cover in the Atlantic Forest project due to enhanced dryness), food web disruptions (e.g., delayed insect emergence in the Central Appalachians with consequences for wildlife), and changes in life history timing such as reproductive season (e.g., changes in recruitment rates of giant clams in the Northern Reefs of Palau due to an increase in ocean acidification).
In terms of underlying climate factors, temperature changes, including warmer ocean temperatures, were the dominant driver of 85 of the potential climate impacts (46%) (Table 4). Precipitation changes and sea level rise were cited 61 (33%) and 24 (13%) times, respectively. The least cited climate factor was ocean acidification (4 citations, 2%).
The predominance of temperature-mediated climate impacts is not especially surprising, but it does reinforce the importance of this fundamental environmental variable. Changing air and sea temperatures are the best documented climate changes and among the most pervasive. As scientific uncertainty about the direction and magnitude of precipitation changes is reduced, we would expect the relative importance of this climate variable to increase. Likewise with sea-level rise and ocean acidification, both of which will likely continue and perhaps accelerate, but about which the conservation implications are only beginning to be understood.
The similarities of expected climate impacts to ‘conventional’ threats raise the possibility that traditional conservation interventions might apply. For example, fire management practices and habitat restoration strategies would remain relevant for restoring appropriate fire regimes and compensating for habitat loss, respectively. However, the magnitude and direction of climate impacts could be different than conventional threats and may require modification of specific actions. For example, climate change could increase hydrologic variability (i.e., more flood events) whereas dams generally reduce such variability. Both affect biodiversity by altering hydrologic regimes, but each would prompt different strategies to compensate for anticipated increases or decreases in variability.
The nature of climate impacts could also prompt conventional conservation strategies to be deployed for different purposes. Corridors have commonly been used as a strategy to reconnect isolated habitat patches and to restore gene flow. Increasing connectivity is also frequently recommended as a core adaptation strategy (Heller and Zavaleta 2009). Our 20 projects suggest that the value of connectivity for climate adaptation is less about compensating for habitat fragmentation, and more about facilitating climate-induced changes in species’ distributions. Thinking about connectivity this way creates a different motive, and possibly leads to different tactics for corridor design in a changing climate (Krosby et al. 2010).
Anticipated changes to focal ecosystems and species
The 20 project teams evaluated potential climate impacts to 75 ecosystems and species. Twelve projects out of 20 (60%) indicated that at least one focal ecosystem or species (or the project boundary) would likely need to change (Fig. 1). On average, project experts anticipated a potential change in one-third of the focal ecosystems or species that they evaluated at the workshop. Eight projects (40%) reported that none of the focal ecosystems or species evaluated at the workshop required adjustment or that more analysis was needed to know if an adjustment was necessary.
Addressing all 75 focal ecosystems and species as a group, 35 (47%) were thought to be unchanged; 17 (23%) needed more analysis to determine if adjustments were necessary; 11 (15%) should likely be adjusted now; 6 (8%) would require a project boundary adjustment to continue to accommodate them; 5 (6%) should no longer be considered in the project area or should be considered elsewhere in the region; and 1 (1%) new focal ecosystem/species was identified.
The Western Arctic conservation project in Alaska, USA and Canada illustrates the types of changes to focal ecosystems and species that were anticipated. Following their climate impact analysis, the project team determined no adjustments were needed to conserve the focal species ‘barren ground caribou’ and ‘bowhead whale.’ In contrast, to continue to conserve ‘ice-dependent marine mammals’ the project’s scope or boundary would need to significantly change from the current delineation and encompass additional areas where ice might remain under warming scenarios. They also determined that ‘benthic fauna’ should be dropped because anticipated severe shifts in species composition due to warmer waters were not feasible to address. Finally, the team felt that further analysis was needed for the ‘greater and lesser scaup’ (e.g., life history, shift in populations) to determine if a major adjustment was needed.
The fact that 40% of the project teams did not make adjustments to their focal ecosystems and species could reflect a general reluctance of conservation practitioners to “give up on anything.” It could also reflect a reality in which conservation options are already constrained such that few modifications are even possible without abandoning a project entirely. Even so, most project teams did indicate numerous modifications of more than half of their focal ecosystems and species. This demonstrates that climate change may necessitate modifications to conservation projects and that conservation practitioners are willing to make appropriate changes when developing adaptation strategies.
Climate adaptation strategies
In response to potential climate impacts, project teams developed a total of 42 adaptation strategies. Each strategy was designed to address a specific climate impact. Instead of attempting to develop strategies for every possible climate impact, project teams were asked to prioritize one to three climate impacts that they felt were the most important for their projects. Project teams were encouraged to develop adaptation strategies for additional climate impacts at their own discretion.
Each adaptation strategy included an objective and a set of one or more actions designed to intervene in anticipation of a specific climate impact. Teams noted whether these strategies included new or adjusted actions compared to their initial conservation strategies, and estimated approximate costs. For example, one adaptation strategy objective for the Northern Reefs of Palau project was “by 2015, identify and effectively protect all resistant and most resilient coral sites in order to increase probability of retaining coral cover in the face of sea surface temperature increases and acidification.” The strategic actions associated with this objective were to: (a) map the most resistant and resilient sites; (b) include special protection of these sites in the management plan; and (c) insure effective enforcement of allowable human activities. This strategy was new to the project and was estimated to cost between $10,000 and $100,000.
In order to describe and compare general features of these adaptation strategies, we categorized strategies as focusing on resistance, resilience, or transformation (after Heller and Zavaleta 2009) (Table 5), identified which strategies included actions that were new or adjusted from earlier non-climate adapted strategies (Table 6), and categorized specific actions associated with each strategy according to the conservation actions taxonomy promulgated under the Open Standards for the Practice of Conservation (CMP 2007) (Table 7). See Supplementary Table 2 for a complete table of adaptation strategies as defined by project teams, and our classifications of those strategies and actions.
Resistance strategies attempt to maintain the status quo of biodiversity in the face of climate change or other climate-exacerbated threats. Such strategies included compensating for changes in water availability, or rebuilding habitat that might be degraded by climate change. Resilience strategies aim to enhance the ability of ecosystems or species to accommodate disturbances induced or exacerbated by climate change (Holling 1973; Gunderson and Holling 2002; Heller and Zavaleta 2009). Such strategies included protecting refugia, creating corridors to allow for species movement or managing for different age and seral stages that are better adapted to anticipated conditions. Transformation strategies aim at protecting or managing for a novel future state, such as changes in ecosystem types that occur with inundation of coastal land with sea level rise or proactively translocating species beyond current range limits. Under these definitions, for example, the Northern Reefs of Palau project cited above was classified as a resilience strategy because it aims to increase the ability of coral reef ecosystems to persist in the face of warmer temperatures and more acidic water. Some adaptation strategies presented a combination of resistance and resilience objectives or resilience and transformation objectives. As with categorization of climate impacts, we allowed for joint categorization in our tallies.
Of the 42 adaptation strategies developed by the 20 conservation projects, 22 (52%) focused on resistance and 18 (45%) focused on resilience. Two strategies included transformation elements—anticipating the need for new policy mechanisms to protect shallow lake bottom habitats that would potentially be exposed as lake levels drop in the Great Lakes, and securing abandoned agricultural land to allow for climate-mediated migration of wetlands (Table 5).
The predominance of resistance strategies contrasts with the literature about climate change and biodiversity management in which resilience strategies were recommended more than twice as often as resistance strategies (Heller and Zavaleta 2009). One possible explanation for this difference is the inherent tendency of conservationists to try to keep things as they are, such that resistance strategies may be preferred whenever possible. Another is that ecosystems and species already at risk may not have the capacity to accommodate further change. In such cases, resilience may sound good in principle, but may not be a practical or possible option in practice to maintain these ecosystems and species.
Regardless of the type of adaptation strategy adopted, climate adaptation strategies consistently departed from business-as-usual. Eighteen (43%) of the strategies the projects developed included entirely new actions not previously considered as part of the original conservation plan. Twenty-four (57%) of the strategies included actions that were adjustments of the original strategies. Only two strategies retained an existing action without modification, but still included new or adjusted actions. Indications were not recorded for 7 strategies (17%) (Table 6). These findings provide strong evidence that considerations of climate change motivate substantive changes in conservation strategies. They also suggest that conservation projects that ignore climate change could be compromised because they are not appropriately tailored to their potential future situation.
To better understand the nature of the actions to be taken under adaptation strategies, we categorized actions according to a standard taxonomy of 21 conservation actions (Salafsky et al. 2008). Some project teams included scientific research and conservation planning actions that did not have an obvious place in the taxonomy. To account for those, we added an additional set of actions to the taxonomy under the general header of “Science and Planning” including scientific research, conservation planning, priority-setting, and monitoring. Most actions were easily assigned to a specific action classification, but a couple could only be assigned to general heading categories.
Adaptation strategies comprised a diversity of actions. Every major category of the action taxonomy was represented except Education and Awareness. Actions to restore habitat and natural processes like hydrologic and fire regimes, and to influence government policies and recommendations were dominant, cited 16 and 13 times, respectively. When actions are viewed in relation to higher-level headings within the taxonomy, science and planning are frequently cited, as are actions related to land and water protection; livelihood, economics & other incentives; and external capacity building (Table 7).
The predominance of habitat restoration and policy actions may be a reflection of The Nature Conservancy’s core competencies—teams may have been predisposed to pursue actions with which they were most familiar and skilled. That notwithstanding, projects prescribed a diversity of actions within their strategies, demonstrating that the challenge of climate adaptation does not have a single, simple solution. Adaptation requires a carefully selected combination of actions to achieve desired outcomes. Just as the specific impacts are varied, so too are the actions that should be taken.
The fact that several project teams indicated a need for more planning and research underscores the need for rigorous science to answer key questions and resolve key uncertainties. This is understandable in this early phase of adaptation strategy development, but project teams must avoid “analysis paralysis” or letting uncertainty be an excuse for delaying reasonable actions.
Costs of adaptation strategies
A possible concern about modifying conservation strategies to account for climate change is that adaptation strategies may be too costly. To assess this concern, we summarized categorical cost estimates provided by project teams. Teams estimated cost as Low (<$10,000), Medium (≥$10,000, <$100,000), High (≥$100,000, <$1,000,000) and Very High (≥$1,000,000). Some teams estimated costs for entire strategies; some reported estimates for each action. In the latter cases, we summed the action-wise cost estimates and recategorized a cost estimate for the entire strategy. Cost estimates were not reported for ten strategies.
Nearly half of the adaptation strategies (15 of 32 strategies for which cost estimates were made) had cost estimates less than $100,000. Seventeen strategies were estimated to cost more than $100,000 or even $1,000,000 (Table 8). Such costs are not inconsequential, but neither are they prohibitively expensive, especially considering the spatial scale of so many of these projects.
Our learning experiment with 20 projects from around the world highlights three major challenges that need to be addressed by institutions engaged with adapting and redesigning conservation projects to climate change. First, adapting to climate change requires clearly linking an explicitly stated expectation about how climate change may affect species, ecosystems, or even people, to clear objectives and actions that can address those climate impacts. The structured process we used for developing adaptation strategies was intended to create clear logic leading from climate impacts to adaptation strategies. For example, the Great Lakes project concluded that increasing air temperature will lead to increased evapotranspiration and a lowering of average seasonal lake levels by 0.5–1.5 m. This in turn will expose shoreline substrate, creating new ground for invasive species and for human development. The project team determined that a key adaptation strategy is to develop policy to ensure that any new exposed bottom land (including wetlands and unvegetated nearshore) is protected from development. Adaptive monitoring could include tracking lake levels, exposed substrate, and the progress of actions toward policy development.
Second, the outcome from our 20-project sample suggests that for the majority of conservation projects, climate impacts will necessitate significant changes, such as changing the project area, reprioritizing or even abandoning some ecosystems or species, revising conservation goals for ecosystems or species, or modifying management actions or interventions. Although not surprising, these results constitute early evidence of how climate change could specifically impact a number of existing conservation projects. Ideally, all conservation projects should evaluate potential adjustments for climate change. Incorporating climate considerations into conservation projects must become the new business as usual, although the institutional mechanisms for achieving this are not yet in place. Key enabling conditions include having an explicit step-by-step methodology, cultivating the ability to take reasoned action despite uncertainty, identifying ‘no-regrets’ strategies that hedge bets against major uncertainties, and further embracing an adaptive conservation paradigm.
Finally, although all of our projects adjusted their strategies in some way, there was a general cautiousness reflected by the fact that only two projects pursued a transformative direction. Leading edge thinking calls for new frameworks for conservation that embrace unavoidable and accelerating change (e.g., Harris et al. 2006; Kareiva and Marvier 2007). For example, Harris et al. (2006, p. 175) states about ecological restoration that:
To this complexity and lack of understanding, we now have to add the fact that environments are changing, and the rate of change is unprecedented. The past is no longer a prescriptive guide for what might happen in the future. There is a large component of ecological restoration that still places considerable value on past ecosystems and seeks to restore the system’s characteristics to its past state. Valuing the past when the past is not an accurate indicator for the future may fulfill a nostalgic need but may ultimately be counterproductive in terms of achieving realistic and lasting restoration outcomes.
Our results indicate a significant gap between theory and practice—understandable for the early stages of climate adaptation. We hypothesize that climate adaptation in reality may require a greater preponderance of transformative strategies, and that scientists and institutions should accelerate exploring such approaches to define and develop the next generation of conservation strategies.