Climate change scenarios forecast increased drought exposure for terrestrial vertebrates in the contiguous United States
Data files
Nov 01, 2024 version files 50.98 MB
-
README.md
3.06 KB
-
Results_analysis_Files.zip
25.14 MB
-
SpeciesChanges_Final.csv
168.90 KB
-
SPEI_processing_Files.zip
25.67 MB
Abstract
Anthropogenic climate change is altering patterns of extreme weather events across the planet, with far-ranging consequences for biodiversity. Increases in the frequency, duration, and severity of droughts are anticipated to substantially impact natural ecosystems. Here, we predicted the extent to which 1,221 terrestrial vertebrates in the contiguous United States will be increasingly exposed to annual (12-month) and prolonged (36-month) drought, under three global climate models and two representative concentration pathways. On average, a 377% increase in annual drought exposure and a 579% increase in prolonged drought exposure are anticipated for the study area by 2050–2080, compared to 1950–2005. Species in the southwestern USA could see the largest increases in drought exposure, while this area also has the highest vertebrate diversity and an abundance of drought-threatened species. Our results aid in identifying vertebrates and ecoregions anticipated to see large increases in drought exposure, which can inform conservation strategies aimed at mitigating vertebrate extinction risks.
https://doi.org/10.5061/dryad.9kd51c5sf
This dataset contains code and shapefiles needed to run the analysis of this paper. The R scripts contain specific information about each section of code, with additional content and instructions.
Description of the data and file structure
Glossary:
SPEI: Standard Precipitation-Evaporation Index - the measurement of drought used in this research.
MACAv2 dataset: downscaled projections of climate data used to obtain modeled historical and future climate data.
PRISM dataset: observed climate data used to obtain observed drought data between 1953–1982 and 1991–2020.
PET: Potential Evapotranspiration, a variable used in combination with precipitation to calculate SPEI values.
Code scripts:
SPEI_calculations.R
Contains all the code necessary to transform the raw climate data from the MACAv2 and PRISM data into monthly SPEI rasters.
Associated files:
- none
SPEI_processing.R
Contains all code necessary to transform the SPEI data, and the associated historical and future periods into rasters of change in drought frequencies (SPEI > 1.5).
Associated files:
- ranges_quartered.shp (shapefile of study area quartered through the centroid)
Results_analysis.R
Contains all the code necessary to run the analysis used to obtain the results and result visualizations.
Associated files:
- ecoregions_raw.shp (shapefile of 74 level III ecoregions used to spatially summarize drought)
- specieslist.xls (XLS of vertebrates included in this analysis)
- monthchanges.csv (CSV file with percentages of change in the number of drought months per quarter of the contiguous USA)
- SpeciesChanges_final.csv (CSV file with projected changes in drought exposure for each vertebrate species under the various future scenarios)
Sharing/Access information
Specific instructions for downloading are provided in the R scripts described above. Data was derived from the following sources:
- Species range data from IUCN: https://www.iucnredlist.org/search/grid?searchType=species
- Study area polygon (cb_2018_us_state_5m.zip): https://www.census.gov/geographies/mapping-files/time-series/geo/carto-boundary-file.html
- Precipitation and PET data for MACAv2 downscaled projections (i.e., modeled climate data): https://climate.northwestknowledge.net/MACA/data_portal.php
- PRISM observed climate data: https://www.fs.usda.gov/rds/archive/products/RDS-2022-0086/_metadata_RDS-2022-0086.html
Code/Software
We used R 4.2.2, all necessary R packages can be found within the R scripts provided.
We used the standardized precipitation evapotranspiration index (SPEI) to calculate past and future drought occurrence in the contiguous United States. To this end, we used three Global Climate Models (GCM) and two Representative Concentration Pathways (RCP), for a historical and future period. We contextualized these findings using observed data for two recent periods. We analyzed changes in drought exposure across species ranges extracted from IUCN and 84 Level III Ecoregions of the United States.
