This page provides links to data that were developed in a new study (Carroll et al. 2018; full citation below), representing the distribution of “climate corridors”, areas that form the best route between current climate types and where those climates will occur in the future under climate change. Because dispersing organisms may need to avoid hostile climates, these routes are often circuitous. Routes were found to be funneled along north-south trending passes and valley systems and along the leeward or drier slopes of north-south trending mountain ranges. Climate connectivity areas, where many potential dispersal routes overlap, were found to be distinct from refugia and thus poorly captured by many existing conservation strategies. Existing parks and protected areas with high importance for climate connectivity were found in southern Mexico, the southwestern US, and western and arctic Canada and Alaska. Areas within southern Mexico, the Great Plains, eastern temperate forests, high Arctic, and western Canadian Cordillera were also found to hold important climate connectivity areas which merit increased conservation focus due to pressures from human land use or due to current low levels of protection. Results from this study can help land managers create more effective responses to climate change by identifying landscape features which promote connectivity among refugia. 

Figure 1. Map of shortest-path and current-flow analysis results for an example climate type located in western North America. Forward shortest paths connecting each current climate location to its closest future analog differ from backward shortest paths connecting each future  climate location to its closest current analog. Current-flow centrality results connect all current and future locations of the climate type by means of diffuse flow rather than single paths.

Figure 2. Results of the current-flow centrality analysis of connectivity in North America between current (1981-2010) and projected future (2071-2100) climate types. Current-flow centrality values represent the net flow of dispersers through a site, and assumes a degree of randomness in dispersal movements. High values were found within north-south trending passes (b) and ridge systems (d), and may avoid areas with disappearing or novel climate types (gray areas in (c)).

Fig. 3. Results of the shortest-path centrality analysis of connectivity in North America between current (1981-2010) and projected future (2071-2100) climate types. Shortest-path centrality values represent the number of overlapping dispersal paths at a site, and assume that dispersers have complete knowledge of the landscape which allows them to identify the single path with least total cost in terms of exposure to non-analogous climate types. Forward (current-to-future) shortest paths are shown in (a), and backward (future-to-current) paths in (b).

Fig. 4. Relative importance of major North American protected areas for climate connectivity, as measured by current-flow centrality values which had been reclassified within 15 EPA Level I ecoregions to ensure representation across broad biome types. 25 of 182 EPA level III ecoregions (areas in gray in figure) fell in the top quintile of reclassified centrality values and either had <10% of their area protected or high levels of anthropogenic pressures which placed them in the top quintile of human footprint values.

Data

The archives linked below provides results from the study in the zipfile format.The archive contains the following files:

• Current-flow centrality values representing connectivity between current (1981-2010 period) to future (2071-2100 period) climate analogs under RCP8.5.
  
• Forward shortest-path centrality values representing connectivity between current (1981-2010 period) to future (2071-2100 period) climate analogs under RCP8.5.
  
• Backward shortest-path centrality values representing connectivity between current (1981-2010 period) to future (2071-2100 period) climate analogs under RCP8.5.
  
• Projection information (lazea.prj)
  
• R script for calculating current-flow and shortest-path centrality based on current and future climate types.
  

These data have been prepared as part of the AdaptWest project and their development was funded by the Wilburforce Foundation. Cite these data as: Carroll, C. , Parks, S. A., Dobrowski, S. Z. and Roberts, D. R. (2018), Climatic, topographic, and anthropogenic factors determine connectivity between current and future climate analogs in North America. Global Change Biology 24:5318-5331. doi:10.1111/gcb.14373.