A look at weather extremes and the big-picture climate connections.

Southwest Turns Anxious Eye to Shrinking Lake Mead

In a dramatic reversal of fortune compared to last year, an unusually dry winter is causing the level of Lake Mead, Nevada, to decline, making water managers increasingly anxious about supplying water to the thirsty Southwest.

The latest U.S. Drought Outlook shows continued dry conditions in the Southwest are likely for the rest of the winter.

During the past three years, the level of Lake Mead has followed a boom and bust cycle, dropping to a record low in 2010 during an intense drought, then recovering during 2011 thanks to record mountain snowfall, and now dropping again in the midst of a dry winter.

According to an article in the Las Vegas Review-Journal, water managers are forecasting the lake level to drop by about 13 feet due to the dry winter so far. As the newspaper reported:

"In December, the U.S. Bureau of Reclamation was predicting a roughly 11-foot rise in Lake Mead over the next year. Now the bureau expects the nation's largest man-made reservoir to shed about 13 feet by January 2013.

One acre-foot equals about 326,000 gallons, which is enough water to supply two average valley homes for one year. At current consumption levels, the 2.45 million acre-foot reduction in Lake Mead's forecast since last month represents enough water to supply the entire Las Vegas Valley for a decade."

During the past 11 years, a particularly dry and warm climate has lingered in Utah, Nevada, Arizona and Southern California, leading to reduced flow along the Colorado River. In fact, scientists have already shown that the stress on the water resources in the Southwest region is consistent with the effects of a warmer climate, and that increased emissions of heat-trapping gases are linked to recent changes in river flows and winter snow pack. Adding to the region's water challenges is the fact that cities that draw water from Lake Mead, such as Las Vegas, have grown in recent years and are further taxing the water supply.

(This Climate Central chart shows how the demand for water from the Colorado River Basin has recently outstripped supply.)

Last year, Climate Central ran an in depth series on water issues in the Southwest, as well as a story that explored how climate change may affect water supplies in the coming decades.


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By TH (Dayton)
on January 29th, 2012

“In fact, scientists have already shown that the stress on the water resources in the Southwest region is consistent with the effects of a warmer climate, and that increased emissions of heat-trapping gases are linked to recent changes in river flows and winter snow pack”

Really? how did they do this?
This article is hyperbole and NOT based on fact.

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By Independent
on January 29th, 2012

Most of those states are Republican and they don’t believe in global warming. Maybe now they will listen to scientists instead of their elected officials.

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By TheDuder (Salmon/ID)
on January 30th, 2012

So, TH, you don’t see supporting evidence so the whole piece is hyperbole and not based on fact? If you don’t know how “they” characterize the effects of a warmer climate on water resources stresses, perhaps you should go out and learn something about it. Go and buy a book based in science. Maybe an entry-level physics book or climate science book. Do you know what the facts are? One fact is that higher temp = high evaporation and transpiration rates. It also means more fires, lower relative humidity, and changes in precipitation and storm tracks. These are very simple relationships.

This piece is based on fact: scientists have shown this. It is a fact. The degree to which warming atmosphere affects water resources will not be determined down to 100% accuracy, but the effects mentioned are quite well understood.

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By David Lewis (Seattle, Washington, 98045)
on January 31st, 2012

“A Great Aridness”, written by WIlliam deBuys, discusses water in the American Southwest - past, present, and future.  Its a well written interesting book written by someone who lives in and who loves the Southwest. 

One thing that struck me in his description of the present day situation is how Arizona faces disaster first if there is an unprecedented drought.  Arizona used to have the same rights as California to its agreed on portion of the Colorado River Basin water but they signed those rights away to get California to stop opposing their bid to get a big federal handout to build the infrastructure necessary to move the water into the Sun Corridor, i.e. the Phoenix and Tucson region.  They got water now to get rich now with no assurance of water later.  They got decades of phenomenal growth out of it.  If Lake Mead dries up, its Arizona that gets cut off first.

Unprecedented drought seems unavoidable even if the global climate was not changing - the commitment of water that was agreed in 1922 in the basin was based on observations from a few wet years in a wet century.  Paleo records show that the 20th century was a wetter than normal century.  The records show that “unprecedented” droughts such as American citizens have never seen have hit repeatedly.  A study of American Southwest water is a study of hypocrisy - all the big projects were federal handouts to these states, and these are the people who tend to pretend they don’t support federal handouts.  Throw climate change in on top of this and crisis threatens to become immediate.  Las Vegas editors sneered when the first study of what would happen to Lake Mead that incorporated climate change projections was published in 2008 - very soon afterward events scared Las Vegas into building the “bathtub” drain, the “third straw” to get the last drop of Lake Mead water if it ever dries up. 

See:  http://theenergycollective.com/david-lewis/74559/arizona-climate-impact-ground-zero

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By ShaKay (Murfreesboro, TN 37129)
on July 18th, 2012

Why aren’t all buildings in Las Vegas, that has @360 sunny days a year, required to use solar energy?
Solar and Wind power, I read complaints about how windy it is near Lake Mead, used to supplement
electric power.  This would greatly reduce how much water is used for hydroelectric power and enable Lake Mead to recover somewhat.  Insist that solar energy be utilized.  I saw a story about a new casino
being built “green”, nothing was ever mentioned about using alternative sources of electricity.  I hope
there will be new rules for all buildings in Las Vegas.

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