Carroll C, Roberts DR, Michalak JL, et al. Scale-dependent complementarity of climatic velocity and environmental diversity for identifying priority areas for conservation under climate change. Glob Change Biol. 2017;23:4508–4520. https://doi.org/10.1111/gcb.13679
…Ready for it? Challenges of Conservation
As humans have taken an increasingly significant toll on the environment, scientists and policymakers have turned to different conservation strategies to preserve and protect our planet’s natural resources. In an ideal world, we would be able to protect all of our natural areas. In reality, we only have limited resources and therefore a common strategy is to pick certain places to turn into protected conservation areas. Typically, planners aim to protect areas that are “high value” in terms of conservation. These can be distinct areas that are rich in biodiversity and span a range of different types of habitats.
This is Why We Can’t Have Nice Things: Impacts of Climate Change
While the task of selecting conservation areas is a challenge on its own, it is further complicated by considering the impact that climate change can have on these areas. Climate change is predicted to cause shifts in where plants and animals live, which means that the distribution of habitats and species across the world will likely look very different in the future than it does today. This poses a particular challenge when trying to define conservation areas. Are the current conservation areas going to remain valuable in the future? If not, can we figure out which areas we should be protecting in anticipation of future conditions?
In a recent study, Carroll et al. explore one way to answer these questions. They investigate modeling the shifts in ecosystems given their current state and the changes we are predicting to occur due to climate change. The goal of these models is to identify climate refugia, or areas which are relatively more resistant to changes in climate and thus can act as refuges for species, supporting biodiversity. One important concept in trying to predict where these refugia might be is climatic velocity. Climatic velocity is the rate at which an organisms that currently live in a certain type of habitat must move in the future in order to remain in the same type of climate as conditions, such as temperature and rainfall, change. Some habitats are expected to change rapidly, which means there is a high climatic velocity, while others will change more slowly.
Call It What You Want: Selecting Metrics for Models
When creating models to identify the best future conservation areas, areas can be prioritized based on metrics such as potential biodiversity, climatic velocity, variety of different types of ecosystems represented, or some combination of all of these. However, since we have no way to know exactly what the future will look like, there is no particular model that is necessarily correct. Rather, we have to try and decide which approach will give us the best prediction given our current knowledge. While it might seem like the more we can incorporate into a model the better the model will be, that is not always the case since it can lead to greater uncertainties. Additionally, these different metrics are spread across vastly different scales. Types of ecosystems generally vary over a large area, whereas topography and diversity can vary over a much smaller area, with climatic velocity falling somewhere in between.
In this paper, Carroll and colleagues explored how to optimize these models by comparing the results from a variety of different models that were programmed to prioritize different metrics. They ran a number of models ranging from ones that optimized single metrics to ones that optimized for different combinations of multiple metrics to identify important conservation areas in North America.
Look What You Made Me Do: Improvements to Models
When Carroll et al. compared the results from different models, they found that results from the models that optimized for biodiversity were quite different from those from ones that optimized for climatic velocity, which they thought to be a result of the different space and time scales over which these metrics change. Because of this, they suggest a two-step approach to improve how these models are being used in conservation planning. First, climatic velocity models can be used to identify larger areas, known as macrorefugia. Then, those areas can be analyzed with diversity metrics to identify smaller areas to target, known as micorefugia.
We can never know if these models are exactly correct, but the more we refine them the more confidence we can have in their results. More work needs to be done to identify the most useful models for identifying valuable conservation areas in the face of future changes, but this paper is an important step in understanding how these models can best be used in conservation planning. These models will be critical for helping planners identify which areas to protect under conservation plans, an important step in protecting ecosystems under the threat of climate change.