This page provides links to several datasets that were generated for and presented in Dobrowski and Parks, 2016 (citation below). These datasets represent metrics of climate change exposure and are based on the premise that unique climates are shifting in response to climate change. The rate of these climatic shifts is termed climate change velocity, which is often invoked as a metric of climate change exposure.
The products provided here measure the distance (and therefore the velocity) between each pixel and its future climate analog in a different manner compared to previous approaches. Notably, the distance is not based on a straight line (i.e. Euclidean distance) between the source and destination pixel, but is instead based on a trajectory that that minimizes exposure to dissimilar climates. The trajectory between each source and destination pixel was delineated using least-cost methods that utilized a resistance surface that penalized dissimilar climates. The distance of this trajectory, or path, is termed the minimum exposure distance (MED). Similarly, the velocity is the length of this trajectory divided by the elapsed time between the reference and future time period and is termed velocityMED. By definition, the MED-based velocity is always greater than or equal to ED-based velocity.
Figure 1. Climate trajectories and minimum cumulative exposure (MCE).
Figure 2. Climate velocity for North America for the interval 1995 to 2085
This dataset also includes an additional measure of climate change exposure that is complementary to velocity-based metrics. This newly developed metric is termed minimum cumulative exposure (MCE) and quantifies the exposure to dissimilar climates (in °C) along each trajectory. That is, each source and destination pixel has an associated trajectory, or path, that was delineated by minimizing exposure, and MCE quantifies the exposure along those trajectories. Generally, regions with little topographic relief have little-to-no MCE because there is no climatic resistance to movement, whereas more topographically complex regions have higher MCE because intervening valleys and mountains between each source and destination pixel have more climatic resistance.
Figure 3. Minimum cumulative exposure (MCE).
Figure 4. Classification of velocity and minimum cumulative exposure (MCE).
Figure 5. Climate trajectories for Yellowstone National Park, USA.
In total, there are five gridded products contained in the zipfile linked below:
1. Minimum exposure distance (MED; km)
2. MED-based climate velocity (velocityMED; km/year)
3. Minimum cumulative exposure (MCE; °C)
4. ED-based velocity (velocityED; km/year)
5. Ratio of MED:ED
The reference climate is represented my mean annual temperature for the years 1981-2010 and the future climate is represented by mean annual temperature for the years 2071-2100. Future climate is an ensemble of 15 CMIP5 GCMs and use the RCP 8.5 emissions scenario. All climate datasets were obtained from AdaptWest (https://adaptwest.databasin.org/).
This dataset has been prepared for the AdaptWest project and was funded by the National Science Foundation and the USFS Rocky Mountain Research Station.
Sample code and input data used in the analysis
Output grids for MED, velocityMED, MCE, velocityED, and ratio of MED:ED