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. 2010 Dec 14;107(50):21256-62.
doi: 10.1073/pnas.0909651107. Epub 2010 Dec 13.

Climate Change and water in Southwestern North America special feature: water, climate change, and sustainability in the southwest

Glen M MacDonald  1
Affiliations

Climate Change and water in Southwestern North America special feature: water, climate change, and sustainability in the southwest

Glen M MacDonald. Proc Natl Acad Sci U S A. .

Abstract

The current Southwest drought is exceptional for its high temperatures and arguably the most severe in history. Coincidentally, there has been an increase in forest and woodland mortality due to fires and pathogenic outbreaks. Although the high temperatures and aridity are consistent with projected impacts of greenhouse warming, it is unclear whether the drought can be attributed to increased greenhouse gases or is a product of natural climatic variability. Climate models indicate that the 21st century will be increasingly arid and droughts more severe and prolonged. Forest and woodland mortality due to fires and pathogens will increase. Demography and food security dictate that water demand in the Southwest will remain appreciable. If projected population growth is twinned with suburb-centered development, domestic demands will intensify. Meeting domestic demands through transference from agriculture presents concerns for rural sustainability and food security. Environmental concerns will limit additional transference from rivers. It is unlikely that traditional supply-side solutions such as more dams will securely meet demands at current per-capita levels. Significant savings in domestic usage can be realized through decreased applications of potable water to landscaping, but this is a small fraction of total regional water use, which is dominated by agriculture. Technical innovations, policy measures, and market-based solutions that increase supply and decrease water demand are all needed. Meeting 21st-century sustainability challenges in the Southwest will also require planning, cooperation, and integration that surpass 20th-century efforts in terms of geographic scope, jurisdictional breadth, multisectoral engagement, and the length of planning timelines.

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Conflict of interest statement

The author declares no conflict of interest.

Figures

Fig. 1
Fig. 1
(A) Composite standardized temperature anomalies for 2001–2009 relative to 1895–2000. (B) Composite standardized precipitation anomalies for 2001–2009 relative to 1895–2000. (C) Mean PDSI values for the period 2001–2009. Data are from ref. and mapped by state climate divisions.
Fig. 2
Fig. 2
(A) Southwest (California, Nevada, Arizona, New Mexico, Utah) average annual temperature (2). (B) Southwest average annual precipitation (2). (C) Southwest average annual Palmer Drought Severity Index (2). (D) Naturalized discharge of the Colorado River at Lees Ferry, AZ (3). (E) Southwest population size (7). (F) Southwest irrigated agricultural land area (8, 9).
Fig. 3
Fig. 3
(A) Southwest average annual temperature (2). (B) Southwest average annual PDSI (2). (C) Southwest water withdrawals by usage sector (4).
See this image and copyright information in PMC

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References

    1. National Drought Mitigation Center US Drought Monitor. http://www.drought.unl.edu/monitor/monitor.htm.
    1. National Oceanic and Atmospheric Administration, Earth System Research Laboratory, Physical Sciences Division http://www.esrl.noaa.gov/psd/data/usclimdivs.
    1. US Bureau of Reclamation Upper Colorado Region. http://www.usbr.gov/uc/water.
    1. Konieczki AD, Heilman JA. Water-use trends in the desert Southwest—1950–2000. US Geological Survey Scientific Investigations Report 2004–5148. 2004
    1. California Department of Forestry and Fire Protection (CAL FIRE) http://www.fire.ca.gov.

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