Lake Powell drought ended? Don’t trust the warming denialists’ predictions

April 20, 2011

Every once in a while a factoid crosses the desk and/or mind of an otherwise badly-informed person who denies global warming is a problem, and without bothering to check the significance of the factoid, the denialist world ramps up The Crazy Rant.

And so, Steve Goddard (who should need no introduction) seized upon a chart that shows a momentary uptick in water in drought-ravaged Lake Powell.  Ignoring more than 50 years of history of the river flows, Goddard pronounced the case for global warming dead.

Former AGW poster child Lake Powell water levels have been rising rapidly over the last few years.

Goddard’s claim is a grand example of the triumph of ignorance over experience, science, data, history and the law, in discussions of climate change.

Did Goddard read his own chart?  It shows a decline in lake level from 2010.

Lake Powell levels, charted by Steve Goddard?

Goddard’s own chart shows a decline in Lake Powell’s March 20 level, from 2010; did he look at the chart? Even Goddard’s source says, “Lake Powell is 89.99 feet below Full Pool (Elevation 3,700).”

“Full pool” level is 3,700 feet elevation (the height of the surface of Lake Powell above sea level).  Goddard’s chart shows the lake hasn’t been at that level since 2000 (and it was declining for some time prior to that).  Goddard’s chart shows four years of rise compared to seven years of decline.

The U.S. Bureau of Reclamation isn’t as optimistic as the warming deniers, noting that drought conditions continue on the Colorado Plateau.

 Upper Colorado River Basin Hydrology

In the Upper Colorado River Basin during water year 2010, the overall precipitation accumulated through September 30, 2010 was approximately 90% of average based on the 30 year average for the period from 1971 through 2000.  For Water Year 2011 thus far, the estimated monthly precipitation within the Upper Colorado River Basin (above Lake Powell) as a percentage of average has been: (October – 135%, November – 95%, December – 225%, January – 50%, February – 100%, March – 90%)

The Climate Prediction Center outlook (dated March 17, 2010) for temperature over the next 3 months indicates that temperatures in the Upper Colorado River Basin are expected to be above average while precipitation over the next 3 months is projected to be near average in the northern reaches of the basin while below average in the southern reaches of the basin.

Upper Colorado River Basin Drought

The Upper Colorado River Basin continues to experience a protracted multi-year drought.  Since 1999, inflow to Lake Powell has been below average in every year except water years 2005 and 2008.  In the summer of 1999, Lake Powell was close to full with reservoir storage at 23.5 million acre-feet, or 97 percent of capacity.  During the next 5 years (2000 through 2004) unregulated inflow to Lake Powell was well below average.  This resulted in Lake Powell storage decreasing during this period to 8.0 million acre-feet (33 percent of capacity) which occurred on April 8, 2005.  During 2005, 2008 and 2009, drought conditions eased somewhat with near or above average inflow conditions and net gains in storage to Lake Powell.  2011 will be another above average inflow year so drought conditions are easing somewhat in the Colorado River Basin. As of April 18, 2011 the storage in Lake Powell was approximately 12.73 million acre-feet (52.3 % of capacity) which is below desired levels.  The overall reservoir storage in the Colorado River Basin as of April 18, 2011 is approximately 31.40 million acre-feet (52.8 % of capacity).
Updated: April 19, 2011

Rick Clayton

Goddard isn’t the first denier to stumble down this path — but can’t they learn from the stumblings of others?  Remember Australia’s “Jo Nova,” who used a photograph of drought-stricken Glen Canyon Dam and environs to claim that warming was not posing problems?  Remember Anthony Watts claiming Lake Powell as a “good proxy” for water in the entire area, and seizing on a momentary uptick?  (Oh, yeah — Watts based his glee on a Goddard note — even repeating Goddard’s error that Lake Powell’s low levels were due to increased use of water in Los Angeles . . .)

Oy.  Do they ever learn?

More, Resources:

The sources from my earlier post on Lake Powell still edify those who bother to read them:

More current sources:

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