Overview

• Forecast species and rare community vulnerability to climate change based on their capacity to adapt biologically
• Map future climate envelopes that will constrain distributions

Details

Assessments of future conditions involve models to forecast the geographic distribution and fate of species. These assessments use climate data generated by a host of different global climate models that each address different assumptions about future CO2 emissions (summarized in IPCC Assessment Reports).

Two basic modeling approaches – both representing types of correlative bioclimatic envelope models – have been used to forecast the potential effects of climate change on species distributions: correlative models and mechanistic models. Correlative models generally link the current distributions of species with current climate using statistical models or machine-learning techniques. These models are often called species distribution models, niche models, climate-envelope models, and more generally, bioclimatic models. Mechanistic models attempt to simulate the distribution of a species based on understood mechanisms (e.g., moisture requirements, competitive interactions, experimentally-derived temperature tolerances). Theoretically, mechanistic models should be more robust for the purpose of projecting potential climate-change impacts; however, the data to build such models is often lacking. Substantial uncertainties are associated with both approaches due to uncertainties in the climate-change projections as well as in the empirical and theoretical relationships upon which the models are founded. Nonetheless, these models have been shown to capture recent range shifts for some species and provide projections that correspond with expected shifts in species distributions.

It is important to be mindful when using any of these approaches that future projections will be based on statistical associations, so that they cannot be used to infer cause-effect relationships. This is a limitation of any current approach to assess future consequences of climate change. Global climate models are built on uncertainties about the likelihood of different CO2 emissions scenarios, as well as how different atmospheric CO2 levels affect the climate system and the biophysical conditions determined by climate. Moreover, future projections based on statistical associations are inherently dependent upon the underlying assumptions of the specific model used to generate the climate and vegetation data. Consequently, decision-makers should be reluctant to use assessments based on data from a single global climate model if small changes in assumptions of any one model produce radically different projections about the future. It is therefore recommended that any of the above assessments should be repeated using input data that bracket the range of climate sensitivity projected by different global climate models. That is, it is recommended that assessments consider using worst-case change scenarios, average-change scenarios and minimal-change scenarios.

The success of management actions to reduce overall vulnerability may also depend on an improved understanding of the adaptive capacity of species and ecosystems. Managing large intact areas will provide species the space required to cope with changes in their environment with their own phenotypic plasticity , genetic diversity , and other factors that contribute to organism’s capacity to adapt to the changing conditions, known as adaptive capacity. Adaptive capacity is “the potential, capability, or ability of a system to adjust to climate change, to moderate potential damages, to take advantage of opportunities, or to cope with the consequences” (IPCC 2007). Adaptive capacity is also considered one of the three major determinants of vulnerability, along with exposure to climate stressors and sensitivity of responses to those stressors. Management adaptation actions are aimed at modifying extrinsic factors in order to maximize the realized adaptive capacity.

Approaches and Tools

• Projected Generalized linear model and logistic regression model
• Maximum entropy models
• Map where species high or low adaptive capacity based on the combination of ecosystem biodiversity and species-level adaptive capacity

Pilot Projects

Overview

• Forecast ecosystem vulnerability to climate change
• Map locations that would support shifts in vegetation types and biomes

Details

Assessments at this level aim to forecast future locations of plant communities. They employ modeling approaches that can map the geographic distribution of vegetation based on biophysical processes (e.g., nutrient cycling, moisture patterns, fire regimes). The models can project potential future locations of vegetation using biophysical data from global climate models such as those used in the IPCC process.

Approaches and Tools

• Dynamic Vegetation Models project broad changes to vegetation communities, biomes, and ecosystem processes (fire, carbon)
• Map projected changes in fire severity based on climate scenarios

Pilot Projects

Overview

• Forecast land-use change
• Project sea-level rise
• Analyze projected trends in climate variables (precipitation, temperature, etc).
• Project climate change
• Map potential future biodiversity hotspots

Details

The landscape-level assessment aims to identify future patterns in landscape conditions. An assessment can examine changes in biophysical conditions (e.g., sea level rise, changes in precipitation patterns) using outputs from climate assessments like the IPCC. They can also build on information gathered for the species and populations level by generating maps that present the future aggregate of individual species distributions (i.e., provide a composite map built on individual species data layers). This composite map can be used to delineate biodiversity hotspots or quantify changes in the number and identity of species across landscapes.

Approaches and Tools

• Map resilience to sea-level rise
• Coastal Resilience Tool
• Map influence of sea-level rise on terrestrial ecosystems
• Sea Level Affecting Marshes Model (SLAMM) tool
• Map climate trends with The Nature Conservancy Climate Wizard

Pilot Projects