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Title: Present-day irrigation mitigates heat extremes

Abstract

Irrigation is an essential practice for sustaining global food production and many regional economies. Emerging scientific evidence indicates that irrigation substantially affects mean climate conditions in different regions of the world. Yet how this practice influences climate extremes is currently unknown. Here we use ensemble simulations with the Community Earth System Model to assess the impacts of irrigation on climate extremes. An evaluation of the model performance reveals that irrigation has a small yet overall beneficial effect on the representation of present-day near-surface climate. While the influence of irrigation on annual mean temperatures is limited, we find a large impact on temperature extremes, with a particularly strong cooling during the hottest day of the year (-0.78 K averaged over irrigated land). The strong influence on extremes stems from the timing of irrigation and its influence on land-atmosphere coupling strength. Together these effects result in asymmetric temperature responses, with a more pronounced cooling during hot and/or dry periods. The influence of irrigation is even more pronounced when considering subgrid-scale model output, suggesting that local effects of land management are far more important than previously thought. In conclusion, our results underline that irrigation has substantially reduced our exposure to hot temperature extremesmore » in the past and highlight the need to account for irrigation in future climate projections.« less

Authors:
ORCiD logo [1];  [2]; ORCiD logo [3]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2]
  1. ETH Zurich (Switzerland). Inst. for Atmospheric and Climate Science; Vrije Univ. Brussel, Brussels (Belgium). Dept. of Hydrology and Hydraulic Engineering
  2. ETH Zurich (Switzerland). Inst. for Atmospheric and Climate Science
  3. National Center for Atmospheric Research, Boulder, CO (United States)
Publication Date:
Research Org.:
Univ. of Maryland, College Park, MD (United States). Univ. Corp for Atmospheric Research
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); US Dept. of Agriculture (USDA); National Center for Atmospheric Research (NCAR), Boulder, CO (United States); ETH Zurich (Switzerland); National Science Foundation (NSF)
OSTI Identifier:
1342255
Alternate Identifier(s):
OSTI ID: 1342256; OSTI ID: 1427802
Grant/Contract Number:
FC03-97ER62402/A010; SC0012972; 2015‐67003‐23489
Resource Type:
Journal Article: Published Article
Journal Name:
Journal of Geophysical Research: Atmospheres
Additional Journal Information:
Journal Volume: 122; Journal Issue: 3; Journal ID: ISSN 2169-897X
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 60 APPLIED LIFE SCIENCES; Irrigation; Climate; extremes

Citation Formats

Thiery, Wim, Davin, Edouard L., Lawrence, David M., Hirsch, Annette L., Hauser, Mathias, and Seneviratne, Sonia I. Present-day irrigation mitigates heat extremes. United States: N. p., 2017. Web. doi:10.1002/2016JD025740.
Thiery, Wim, Davin, Edouard L., Lawrence, David M., Hirsch, Annette L., Hauser, Mathias, & Seneviratne, Sonia I. Present-day irrigation mitigates heat extremes. United States. doi:10.1002/2016JD025740.
Thiery, Wim, Davin, Edouard L., Lawrence, David M., Hirsch, Annette L., Hauser, Mathias, and Seneviratne, Sonia I. Thu . "Present-day irrigation mitigates heat extremes". United States. doi:10.1002/2016JD025740.
@article{osti_1342255,
title = {Present-day irrigation mitigates heat extremes},
author = {Thiery, Wim and Davin, Edouard L. and Lawrence, David M. and Hirsch, Annette L. and Hauser, Mathias and Seneviratne, Sonia I.},
abstractNote = {Irrigation is an essential practice for sustaining global food production and many regional economies. Emerging scientific evidence indicates that irrigation substantially affects mean climate conditions in different regions of the world. Yet how this practice influences climate extremes is currently unknown. Here we use ensemble simulations with the Community Earth System Model to assess the impacts of irrigation on climate extremes. An evaluation of the model performance reveals that irrigation has a small yet overall beneficial effect on the representation of present-day near-surface climate. While the influence of irrigation on annual mean temperatures is limited, we find a large impact on temperature extremes, with a particularly strong cooling during the hottest day of the year (-0.78 K averaged over irrigated land). The strong influence on extremes stems from the timing of irrigation and its influence on land-atmosphere coupling strength. Together these effects result in asymmetric temperature responses, with a more pronounced cooling during hot and/or dry periods. The influence of irrigation is even more pronounced when considering subgrid-scale model output, suggesting that local effects of land management are far more important than previously thought. In conclusion, our results underline that irrigation has substantially reduced our exposure to hot temperature extremes in the past and highlight the need to account for irrigation in future climate projections.},
doi = {10.1002/2016JD025740},
journal = {Journal of Geophysical Research: Atmospheres},
number = 3,
volume = 122,
place = {United States},
year = {Thu Feb 16 00:00:00 EST 2017},
month = {Thu Feb 16 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1002/2016JD025740

Citation Metrics:
Cited by: 7works
Citation information provided by
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  • Cited by 7
  • Irrigation is an essential practice for sustaining global food production and many regional economies. Emerging scientific evidence indicates that irrigation substantially affects mean climate conditions in different regions of the world. Yet how this practice influences climate extremes is currently unknown. Here we use ensemble simulations with the Community Earth System Model to assess the impacts of irrigation on climate extremes. An evaluation of the model performance reveals that irrigation has a small yet overall beneficial effect on the representation of present-day near-surface climate. While the influence of irrigation on annual mean temperatures is limited, we find a large impactmore » on temperature extremes, with a particularly strong cooling during the hottest day of the year (-0.78 K averaged over irrigated land). The strong influence on extremes stems from the timing of irrigation and its influence on land-atmosphere coupling strength. Together these effects result in asymmetric temperature responses, with a more pronounced cooling during hot and/or dry periods. The influence of irrigation is even more pronounced when considering subgrid-scale model output, suggesting that local effects of land management are far more important than previously thought. In conclusion, our results underline that irrigation has substantially reduced our exposure to hot temperature extremes in the past and highlight the need to account for irrigation in future climate projections.« less
  • This article examines the rapid expansion of sewage irrigation in China. The objective factors for the expansion are that China's water resources are less than plentiful, plus the fact that the steadily increasing use of water by industry and agriculture produces a corresponding increase of waste water. China's total annual precipitation is about 6 trillion cubic meters, the total annual volume of runoff about 2.6 trillion cubic meters, and the per capital volume of flow is only 2,700 cubic meters, which is one-fourth of the world average. The subjective factors accountable for the rapid development of sewage irrigation in Chinamore » are that city sewage provides the farmland of some localities a steady source of water, and that the peasants want to use it because the sewage contains fertilizers and trace chemicals which enhance the development of crops. Topics considered include the impact of sewage irrigation on the agricultural environment, and the development of sewage irrigation in China through regional systems of comprehensive prevention and control.« less
  • Thermal conductivity is a familiar property of materials: silver conducts heat well, and plastic does not. In recent years, an interdisciplinary group of materials scientists, engineers, physicists, and chemists have succeeded in pushing back long-established limits in the thermal conductivity of materials. Carbon nanotubes and graphene are at the high end of the thermal conductivity spectrum due to their high sound velocities and relative lack of processes that scatter phonons. Unfortunately, the superlative thermal properties of carbon nanotubes have not found immediate application in composites or interface materials because of difficulties in making good thermal contact with the nanotubes. Atmore » the low end of the thermal conductivity spectrum, solids that combine order and disorder in the random stacking of two-dimensional crystalline sheets, so-called "disordered layered crystals," show a thermal conductivity that is only a factor of 2 larger than air. The cause of this low thermal conductivity may be explained by the large anisotropy in elastic constants that suppresses the density of phonon modes that propagate along the soft direction. Low-dimensional quantum magnets demonstrate that electrons and phonons are not the only significant carriers of heat. Near room temperature, the spin thermal conductivity of spin-ladders is comparable to the electronic thermal conductivities of metals. Our measurements of nanoscale thermal transport properties employ a variety of ultrafast optical pump-probe metrology tools that we have developed over the past several years. We are currently working to extend these techniques to high pressures (60 GPa), high magnetic fields (5 T), and high temperatures (1000 K).« less
  • The WRF-Chem model coupled with a single-layer urban canopy model (UCM) is integrated for 5 years at convection-permitting scale to investigate the individual and combined impacts of urbanization-induced changes in land cover and pollutant emissions on regional climate in the Yangtze River Delta (YRD) region in eastern China. Simulations with the urbanization effects reasonably reproduced the observed features of temperature and precipitation in the YRD region. Urbanization over the YRD induces an urban heat island (UHI) effect, which increases the surface temperature by 0.53 °C in summer and increases the annual heat wave days at a rate of 3.7 d yr −1 in themore » major megacities in the YRD, accompanied by intensified heat stress. In winter, the near-surface air temperature increases by approximately 0.7 °C over commercial areas in the cities but decreases in the surrounding areas. Radiative effects of aerosols tend to cool the surface air by reducing net shortwave radiation at the surface. Compared to the more localized UHI effect, aerosol effects on solar radiation and temperature influence a much larger area, especially downwind of the city cluster in the YRD. Results also show that the UHI increases the frequency of extreme summer precipitation by strengthening the convergence and updrafts over urbanized areas in the afternoon, which favor the development of deep convection. In contrast, the radiative forcing of aerosols results in a surface cooling and upper-atmospheric heating, which enhances atmospheric stability and suppresses convection. The combined effects of the UHI and aerosols on precipitation depend on synoptic conditions. Two rainfall events under two typical but different synoptic weather patterns are further analyzed. It is shown that the impact of urban land cover and aerosols on precipitation is not only determined by their influence on local convergence but also modulated by large-scale weather systems. For the case with a strong synoptic forcing associated with stronger winds and larger spatial convergence, the UHI and aerosol effects are relatively weak. When the synoptic forcing is weak, however, the UHI and aerosol effects on local convergence dominate. This suggests that synoptic forcing plays a significant role in modulating the urbanization-induced land-cover and aerosol effects on individual rainfall event. Hence precipitation changes due to urbanization effects may offset each other under different synoptic conditions, resulting in little changes in mean precipitation at longer timescales.« less