Protected area networks are a key management tool for maintaining biodiversity and keeping species connected. However, many were designed without climate change in mind, and may need to be restructured given future projections. Some suggestions for adapting protected area networks for climate change include increasing the number of reserves, the size of reserves, or increasing their connectivity.
But it’s one thing to make suggestions about adapting to climate change, and another to incorporate them into the planning process. Practical considerations, such as which specific strategy is most useful or which is most cost-effective, are often what drives decision-makers.
To make these decisions easier, a new study compares the distributions and relative costs of several different strategies to addressing climate change. This is done within the United States protected area network and based on habitat suitability for over 1,400 plants and vertebrates.
One strategy targets current species distributions by asking what would happen if we augmented the current network with areas projected to be suitable for species today. Another strategy targets species-specific refugia by augmenting the current network with areas projected to be suitable for species today and into the future. Yet another strategy targets climate refugia by augmenting with areas projected to be currently suitable for species as well as climate analogues of habitats that are rapidly disappearing. A final strategy targets connectivity by augmenting with areas projected to be currently suitable for species as well as climate corridors that support climate-driven movement.
These different strategies turn out to have a lot of variation in effectiveness and relative cost. For example, expanding the network based only on species’ current climatic suitability failed to protect areas that will be climatically suitable in the future for 14% of the species. In addition, a strategy that incorporates both current and future climatically suitable areas would increase costs by 59%. Incorporating different levels of climate refugia (ex. 40% vs 100% of possible areas) and different levels of climate corridors changed costs as well. However, compared to the cost of expanding reserve networks without any consideration of climate change, protecting some types of climatic refugia may be a relatively inexpensive way to adapt.
Species generally have three ways to respond to climate change: adapt, move, or die. Protected area networks are good for helping species adapt or move, but only if they’re designed in a strategic way. Practical considerations like design and cost are inherent parts of planning and need to be addressed within any recommendations. Better informed decisions lead to better designed networks and greater ability to protect biodiversity.