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Title: Competing Influences of Anthropogenic Warming, ENSO, and Plant Physiology on Future Terrestrial Aridity

The 2011–16 California drought illustrates that drought-prone areas do not always experience relief once a favorable phase of El Niño–Southern Oscillation (ENSO) returns. In the twenty-first century, such an expectation is unrealistic in regions where global warming induces an increase in terrestrial aridity larger than the changes in aridity driven by ENSO variability. This premise is also flawed in areas where precipitation supply cannot offset the global warming–induced increase in evaporative demand. Here, atmosphere-only experiments are analyzed to identify land regions where aridity is currently sensitive to ENSO and where projected future changes in mean aridity exceed the range caused by ENSO variability. Insights into the drivers of these changes in aridity are obtained using simulations with the incremental addition of three different factors to the current climate: ocean warming, vegetation response to elevated CO 2 levels, and intensified CO 2 radiative forcing. The effect of ocean warming overwhelms the range of ENSO-driven temperature variability worldwide, increasing potential evapotranspiration (PET) in most ENSO-sensitive regions. Additionally, about 39% of the regions currently sensitive to ENSO will likely receive less precipitation in the future, independent of the ENSO phase. Consequently aridity increases in 67%–72% of the ENSO-sensitive area. When both radiative andmore » physiological effects are considered, the area affected by arid conditions rises to 75%–79% when using PET-derived measures of aridity, but declines to 41% when an aridity indicator for total soil moisture is employed. This reduction mainly occurs because plant stomatal resistance increases under enhanced CO 2 concentrations, resulting in improved plant water-use efficiency, and hence reduced evapotranspiration and soil desiccation. Imposing CO 2-invariant stomatal resistance may overestimate future drying in PET-derived indices.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [3] ;  [1] ;  [4]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Universite de Lorraine (France). Annuaire des Laboratoires et des Recherches
  3. Columbia Univ., New York, NY (United States); NASA Goddard Inst. for Space Studies (GISS), New York, NY (United States)
  4. Lawrence Livermore National Laboratory, Livermore, California
Publication Date:
Report Number(s):
LLNL-JRNL-731283
Journal ID: ISSN 0894-8755
Grant/Contract Number:
AC52-07NA27344; FOA-0001036
Type:
Published Article
Journal Name:
Journal of Climate
Additional Journal Information:
Journal Volume: 30; Journal Issue: 17; Journal ID: ISSN 0894-8755
Publisher:
American Meteorological Society
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Atmosphere-land interaction; Teleconnections; Drought; ENSO; Climate models; Climate variability
OSTI Identifier:
1372956
Alternate Identifier(s):
OSTI ID: 1389970

Bonfils, Céline, Anderson, Gemma, Santer, Benjamin D., Phillips, Thomas J., Taylor, Karl E., Cuntz, Matthias, Zelinka, Mark D., Marvel, Kate, Cook, Benjamin I., Cvijanovic, Ivana, and Durack, Paul J.. Competing Influences of Anthropogenic Warming, ENSO, and Plant Physiology on Future Terrestrial Aridity. United States: N. p., Web. doi:10.1175/JCLI-D-17-0005.1.
Bonfils, Céline, Anderson, Gemma, Santer, Benjamin D., Phillips, Thomas J., Taylor, Karl E., Cuntz, Matthias, Zelinka, Mark D., Marvel, Kate, Cook, Benjamin I., Cvijanovic, Ivana, & Durack, Paul J.. Competing Influences of Anthropogenic Warming, ENSO, and Plant Physiology on Future Terrestrial Aridity. United States. doi:10.1175/JCLI-D-17-0005.1.
Bonfils, Céline, Anderson, Gemma, Santer, Benjamin D., Phillips, Thomas J., Taylor, Karl E., Cuntz, Matthias, Zelinka, Mark D., Marvel, Kate, Cook, Benjamin I., Cvijanovic, Ivana, and Durack, Paul J.. 2017. "Competing Influences of Anthropogenic Warming, ENSO, and Plant Physiology on Future Terrestrial Aridity". United States. doi:10.1175/JCLI-D-17-0005.1.
@article{osti_1372956,
title = {Competing Influences of Anthropogenic Warming, ENSO, and Plant Physiology on Future Terrestrial Aridity},
author = {Bonfils, Céline and Anderson, Gemma and Santer, Benjamin D. and Phillips, Thomas J. and Taylor, Karl E. and Cuntz, Matthias and Zelinka, Mark D. and Marvel, Kate and Cook, Benjamin I. and Cvijanovic, Ivana and Durack, Paul J.},
abstractNote = {The 2011–16 California drought illustrates that drought-prone areas do not always experience relief once a favorable phase of El Niño–Southern Oscillation (ENSO) returns. In the twenty-first century, such an expectation is unrealistic in regions where global warming induces an increase in terrestrial aridity larger than the changes in aridity driven by ENSO variability. This premise is also flawed in areas where precipitation supply cannot offset the global warming–induced increase in evaporative demand. Here, atmosphere-only experiments are analyzed to identify land regions where aridity is currently sensitive to ENSO and where projected future changes in mean aridity exceed the range caused by ENSO variability. Insights into the drivers of these changes in aridity are obtained using simulations with the incremental addition of three different factors to the current climate: ocean warming, vegetation response to elevated CO2 levels, and intensified CO2 radiative forcing. The effect of ocean warming overwhelms the range of ENSO-driven temperature variability worldwide, increasing potential evapotranspiration (PET) in most ENSO-sensitive regions. Additionally, about 39% of the regions currently sensitive to ENSO will likely receive less precipitation in the future, independent of the ENSO phase. Consequently aridity increases in 67%–72% of the ENSO-sensitive area. When both radiative and physiological effects are considered, the area affected by arid conditions rises to 75%–79% when using PET-derived measures of aridity, but declines to 41% when an aridity indicator for total soil moisture is employed. This reduction mainly occurs because plant stomatal resistance increases under enhanced CO2 concentrations, resulting in improved plant water-use efficiency, and hence reduced evapotranspiration and soil desiccation. Imposing CO2-invariant stomatal resistance may overestimate future drying in PET-derived indices.},
doi = {10.1175/JCLI-D-17-0005.1},
journal = {Journal of Climate},
number = 17,
volume = 30,
place = {United States},
year = {2017},
month = {7}
}