DOI: 10.5061/dryad.bcc2fqzpx
title: Data for: Climate change increases evaporative and crop irrigation demand in North America

description: Across North America, warmer temperatures have increased reference
 evapotranspiration (ETo), taxing water resources. This problem is
 especially pronounced for semi-arid regions with large amounts of
 irrigated agriculture, such as California’s Central Valley. In this
 region, increased ETo has increased irrigation demand, but the role of
 anthropogenic climate change (ACC) in driving this increase has not yet
 been quantified. Here, we quantify the first-order influence of ACC on ETo
 and how these changes have translated into increased irrigation demand. We
 calculated observed and counterfactual ETo over North America using
 ERA5-Land data and 20 models from the Coupled Model Intercomparison
 Project Phase 6 (CMIP6). At the scale of North America, we found that ACC
 accounted for all of the observed ETo increase (1.06 mm/yr) during
 1980-2022. The largest observed increases in ETo were found in the
 southwestern and central regions, where ACC has likely exacerbated trends
 linked to natural climate variability. The largest ACC contributor to
 increased ETo was increased vapor pressure deficit, while decreased solar
 radiation has tempered increased ETo. We estimated that the first-order
 influence of ACC on agricultural irrigation demands in the Central Valley
 was equivalent to ~11% of the region’s groundwater loss during this time.
 Our findings suggest that ACC is accelerating demand for water in this
 already water-limited region.  
description: # Data for: Climate change increases evaporative and crop irrigation
 demand in North America
 [https://doi.org/10.5061/dryad.bcc2fqzpx](https://doi.org/10.5061/dryad.bcc2fqzpx) ## Description of the data and file structure These data files accompany the manuscript, Climate Change Increases Reference Evapotranspiration and Crop Irrigation Demand in North America. Files included are observational ETo, CO2-adjusted observational ETo, and four estimates of counterfactual ETo (with forced contributions from T + RH, windspeed, solar radiation, and all variables removed).  Observational and CO2-adjusted observational ETo were calculated from ERA5-Land using the Penman-Monteith Equation. Counterfactual ETo files were created by removing forced trends in each / variable from ERA5-Land; forced trends calculated using a low-pass filter on GCM data from CMIP6. ### Files and variables #### File: ETo\_co2adj\_era5land\_obs.nc **Description:** CO2-adjusted observational ETo (mm) #### File: ETo\_era5land\_counterfactual\_solar.nc **Description:** Counterfactual ETo (mm) with forced trends in solar radiation removed.  #### File: ETo\_era5land\_counterfactual\_vpd.nc **Description:** Counterfactual ETo (mm) with forced trends in temperature and relative humidity removed.  #### File: ETo\_era5land\_counterfactual\_wind.nc **Description:** Counterfactual ETo (mm) with forced trends in wind speed removed.  #### File: ETo\_era5land\_counterfactual.nc **Description:** Counterfactual ETo (mm) with forced trends in all variables removed.  #### File: ETo\_era5land\_obs.nc **Description:** Observational ETo (mm).