Climatic distributional shifts and refugia for North American ecoregions

Climate-projected distributional shifts and refugia for North American ecoregions

Climate model projections suggest major North American biome shifts in response to anthropogenic climate change (Rehfeldt et al. 2012). Such shifts could have profound influences on native flora and fauna, many of which would have to move long distances to track their climatic niches. To evaluate potential ecosystem changes at a somewhat finer scale, I projected the change in climate space for level III ecoregions (Commission for Environmental Cooperation 1997) as surrogates for multiple associated species and ecological communities. First, I developed a random forest model (Breiman 2001) to predict ecoregion class from bioclimatic variables (see Table 1 in pdf), using 1-km interpolated climate data for the 1969-1990 normal period (Hamann et al. 2013), available at http://adaptwest.databasin.org/pages/adaptwest-climatena.

This model was then used to project ecoregions onto future mid-century (2041-2070) and end-of-century (2071-2100) climate conditions. Climate projections were based on 1-km downscaled climate anomalies (Wang et al. 2016) generated by an ensemble of 15 widely-used GCMs from the Coupled Model Intercomparison Project, Phase 5 (CMIP5, Taylor et al. 2012), available at http://adaptwest.databasin.org. I used representative concentration pathway (RCP) 8.5, to represent the 21st century conditions that are to be expected without dramatic reductions in greenhouse gas emissions or technological fixes (Fuss et al. 2014). I also evaluated RCP 4.5 to represent a future in which significant emissions reductions are achieved. The change in area was also calculated for each Level III ecoregion (see Table 2 in pdf).

Results for RCP 4.5 and RCP 8.5 are shown below in Figures 1 and 2, respectively.

Figure 1 

Figure 1. Model-predicted (a) baseline, (b) mid-century, and (c) end-of-century changes in North American ecoregions for RCP 4.5. Boreal, hemi-boreal, and western forested regions are shown in green and blue-green shades; arctic ecoregions are in blue shades; prairie/parkland ecoregions are in brown shades; and temperate forest ecoregions are in yellow and orange shades (see Table 1 for full list of ecoregions). Boreal ecoregions are also outlined in black.

Figure 2 

Figure 2. Model-predicted (a) baseline, (b) mid-century, and (c) end-of-century changes in North American ecoregions for RCP 8.5. Boreal, hemi-boreal, and western forested regions are shown in green and blue-green shades; arctic ecoregions are in blue shades; prairie/parkland ecoregions are in brown shades; and temperate forest ecoregions are in yellow and orange shades (see Table 1 for full list of ecoregions). Boreal ecoregions are also outlined in black.

Data can be downloaded or viewed below, and are also found on Zenodo.org at http://doi.org/10.5281/zenodo.1407176

Cite this data as: Stralberg, D. 2018. Climate-projected distributional shifts and refugia for North American ecoregions. http://doi.org/10.5281/zenodo.1407176. Available at https://adaptwest.databasin.org. 


Data files
Download
All files, zip format (65 MB)
Zipfile
Supplemental information Link
Individual rasters as Databasin map layers

Predicted ecoregions, current period  Map layer
Predicted ecoregions, RCP 4.5,  2050s Map layer
Predicted ecoregions, RCP 4.5,  2080s Map layer
Predicted ecoregions, RCP 8.5,  2050s Map layer
Predicted ecoregions, RCP 8.5,  2080s Map layer

Data layers 
-----------------
Data layers represent ecoregion projections at 1-km resolution for North America: 
_predcurrent.tif
_pred_XXXXX_YYYY.tif
where:
XXXXX = Representative Concentration Pathway (rcp45 or rcp85)
YYYYY = Time period (2050s or 2080s)


See "ecoregion_lookup.csv" for ecoregion definitions and projected change summaries.


Projection information
-------------------
"+proj=lcc +lat_1=49 +lat_2=77 +lat_0=0 +lon_0=-95 +x_0=0 +y_0=0 +ellps=GRS80 +units=m +no_defs"
-------------------
Projection    LAMBERT
Spheroid      GRS80
Units         METERS
Zunits        NO
Xshift        0.0
Yshift        0.0
Parameters    
49  0  0.0 /* 1st standard parallel
77  0  0.0 /* 2nd standard parallel
-95  0  0.0 /* central meridian
0  0  0.0 /* latitude of projection's origin
0.0 /* false easting (meters)
0.0 /* false northing (meters)


REFERENCES

Breiman, L. 2001. Random Forests. Machine Learning 45:5-32.

Commission for Environmental Cooperation. 1997. Ecological Regions of North America: Toward a Common Perspective, Montreal, Canada.

Fuss, S., J. G. Canadell, G. P. Peters, M. Tavoni, R. M. Andrew, P. Ciais, R. B. Jackson, C. D. Jones, F. Kraxner, N. Nakicenovic, C. Le Quere, M. R. Raupach, A. Sharifi, P. Smith, and Y. Yamagata. 2014. Betting on negative emissions. Nature Climate Change 4:850-853.

Hamann, A., T. Wang, D. L. Spittlehouse, and T. Q. Murdock. 2013. A comprehensive, high-resolution database of historical and projected climate surfaces for western North America. Bulletin of the American Meteorological Society 94:1307-1309.

Rehfeldt, G. E., N. L. Crookston, C. Sáenz-Romero, and E. M. Campbell. 2012. North American vegetation model for land-use planning in a changing climate: a solution to large classification problems. Ecological Applications 22:119-141.

Taylor, K. E., R. J. Stouffer, and G. A. Meehl. 2012. An Overview of CMIP5 and the Experiment Design. Bulletin of the American Meteorological Society 93:485-498.

Wang, T., A. Hamann, D. Spittlehouse, and C. Carroll. 2016. Locally Downscaled and Spatially Customizable Climate Data for Historical and Future Periods for North America. PLoS ONE 11:e0156720.