U.S. Department of Energy Office of Biological and Environmental Research

BER Research Highlights


Future Climate Warming Induces Emergence of New Hydrologic Regimes of Surface Water Resources in the Conterminous United States
Published: October 25, 2016
Posted: May 10, 2017

Global warming poses great challenges to the future U.S. surface water supply.

The Science  
Future climate change projections often focus on average trends over time, or zero in on changes in extreme events. When evaluating climate change impacts, however, it is often important to consider additional parameters, such as changes in the seasonality of runoff. This study evaluates whether the overall pattern of surface water supply in a given watershed has shifted significantly away from historical conditions—that is, when it is projected to enter a new “hydrological regime”— using a statistical technique, and finds that more than 40% of the continental United States land area is likely to experience a significant hydrological regime shift by the end of the 21st century.

The Impact
Many human and natural systems have evolved in the context of a relatively stable climate, so it is important to understand when and where climate change could push systems across thresholds that would result in rapid, nonlinear changes. This study assessed changes in the probability distributions of surface water resources in large (HUC-4) sub-basins across the United States under a range of future climate projections. The research found that each 1°C increase in global mean temperature was associated with an 11-17% increase in land area experiencing a new hydrologic regime, which could pose significant challenges to water resource managers. Northern California and the Pacific Northwest are projected to experience these regime shifts by 2030, earlier than other US regions.

Summary
Researchers at the Department of Energy’s Pacific Northwest National Laboratory (PNNL) analyzed runoff projections from the Variable Infiltration Capacity (VIC) hydrological model which was driven by 97 downscaled and bias-corrected Coupled Model Intercomparison Project Phase 5 (CMIP5) climate projections over the conterminous United States (CONUS). A statistical technique based on the two-sample Kolmogorov-Smirnov test was used to determine the year in which the summer and winter surface runoff in each sub-basin shifted to a new regime in each of these projections, compared to the simulated historical hydroclimate from 1970-1999. They found that the overall land area experiencing a significant hydrologic regime shift followed a linear relationship with respect to global mean temperature, with 11-17% more lands experiencing statistically significant changes in winter and summer runoff across all scenarios and models considered. Further decomposition showed that the emergence of new runoff regimes is typically dominated by changes in variability, rather than shifts in average runoff, and that these runoff regime shifts are driven by an increase in the year-to-year variability of precipitation across many future climate scenarios.

Contacts (BER PM)
Robert Vallario
Integrated Assessment Research Program
Bob.Vallario@science.doe.gov

David Lesmes and Paul Bayer
Subsurface Biogeochemical Research
David.Lesmes@science.doe.gov and Paul.Bayer@science.doe.gov

(PI Contacts)
Maoyi Huang
Pacific Northwest National Laboratory
Maoyi.Huang@pnnl.gov

Funding
This study was conducted with support from the US Department of Energy’s Office of Science, Office of Biological and Environmental Research (BER) for the Subsurface Biogeochemical Research (SBR) program through the PNNL SBR SFA, and the BER’s Integrated Assessment Research Program for the Regional Integrated Assessment Modeling project (RIAM).

Publications
Leng, G., et al., “Emergence of new hydrologic regimes of surface water resources in the conterminous United States under future warming,” Environmental Research Letters, 11(11):114003, (2016). DOI:10.1088/1748-9326/11/11/114003 (Reference link)

Topic Areas:

  • Research Area: Multisector Dynamics (formerly Integrated Assessment)
  • Research Area: Subsurface Biogeochemical Research

Division: SC-23.1 Climate and Environmental Sciences Division, BER

 

BER supports basic research and scientific user facilities to advance DOE missions in energy and environment. More about BER

Recent Highlights

Aug 24, 2019
New Approach for Studying How Microbes Influence Their Environment
A diverse group of scientists suggests a common framework and targeting of known microbial processes [more...]

Aug 08, 2019
Nutrient-Hungry Peatland Microbes Reduce Carbon Loss Under Warmer Conditions
Enzyme production in peatlands reduces carbon lost to respiration under future high temperatures. [more...]

Aug 05, 2019
Amazon Forest Response to CO2 Fertilization Dependent on Plant Phosphorus Acquisition
AmazonFACE Model Intercomparison. The Science Plant growth is dependent on the availabi [more...]

Jul 29, 2019
A Slippery Slope: Soil Carbon Destabilization
Carbon gain or loss depends on the balance between competing biological, chemical, and physical reac [more...]

Jul 15, 2019
Field Evaluation of Gas Analyzers for Measuring Ecosystem Fluxes
How gas analyzer type and correction method impact measured fluxes. The Science A side- [more...]

List all highlights (possible long download time)