Severity of drought conditions across the country: dark is worse: From New York Times
An interesting article appeared in the NYT on the drought conditions in California and whether or not it relates to global climate change. The stimulus for the article was Obama’s visit to the region, where he cited global climate change as the source or at least a contributing factor to California’s serious water shortage problem. But the far more interesting point about the article is that it revealed competing models from climatologists who do not agree on whether the current drought represents a deepening from global climate change mechanisms or if the drought conditions represent a weather event that is part of the normal weather cycle, even though this one tips the all time scales as the state’s driest weather span in recorded history.
To begin with, 2013 was the driest year in the 119 years that California has been keeping records, so some have argued that this is a one in 500 year drought, no matter what the cause. Our general understanding of global climate change means wet areas will get wetter and dry areas will get drier and while California is going through a horrendous water shortage experience, other parts of the country have received wetter than normal winters, including the Midwest and East Coast.
Climate scientist Jacob O. Sewall, published a paper in 2004 based on modeling the influence of a reductions of Arctic sea ice, which has been melting much faster than earlier predictions had projected. Indeed, we are near the mid 20th century level based on earlier projections for arctic ice melting. What Sewall’s model revealed was that increased melting of arctic sea ice caused a warming of the atmosphere due to less reflectance of light from the ice, and this albedo effect had an influence on a huge slice of atmospheric weather conditions, one of which was to create a high pressure region off the coast of California: such a high pressure region has been parked there for the last three years. This high pressure mass makes it more likely that moisture-bearing storms will travel a more northerly route and will more likely dump moisture on Seattle rather than Sacramento.
But Richard Seager, a climate scientist at Columbia University who studies water issues, feels that California’s current drought has been created by natural environmental conditions, not global warming, claiming they are a lot like those in the 1970s, although it wasn’t clear the data on which he based his conclusions, other than gross similarities. Heavy rains in the northern California have reduced the drought conditions somewhat during this month but the reservoirs are only about half full from where they need to be for adequate water. California gets much of its water from snow in the winter along the western slopes of the Sierra Nevada. That means 38 million people and a $45 billion agricultural economy are critically dependent on about five heavy snow storms a year, making the annual snowfall seem more like global climate gambling.
Other sources of Water for California: California also gets a share of water from the Colorado River Project through an agreement that goes back to 1922 and includes, for the lower basin, fed by water stored in Lake Mead with recipients including California, Nevada, Arizona and Mexico. But this source of water is being challenged by drought as well: [From Jeff Masters' Wunderblog] “For the first time in history, the U.S. government has ordered that flow of Colorado River water from the 50-year-old Glen Canyon Dam be slashed, due to a water crisis brought about by the region’s historic 14-year drought. On Friday, the Federal Bureau of Reclamation–a division of the Department of Interior that manages water and electric power in the West–announced that it would cut water released from Lake Powell’s Glen Canyon Dam by 750,000 acre-feet in 2014. An acre-foot is the amount of water that will cover an acre of land one foot deep; 750,000 acre-feet is enough water to supply at least 750,000 homes for one year. The flow reduction will leave the Colorado River 9% below the 8.23 million acre feet that is supposed to be supplied downstream to Lake Mead for use in California, Nevada, Arizona and Mexico under the Colorado River Compact of 1922 and later agreements. “This is the worst 14-year drought period in the last hundred years,” said Upper Colorado Regional Director Larry Walkoviak in a Bureau of Reclamation press release.“
Lake Powell 1999 and 2013
“In the winter of 2005, Lake Powell reached its lowest level since filling, an elevation 150′ below full pool. Lake levels recovered some in 2005 – 2011, but the resurgence of severe to extreme drought conditions have provoked a steep decline in 2012 and 2013, with the lake falling 35′ over the past year. As of August 18, 2013, Lake Powell was 109′ below full pool (45% of capacity), and was falling at a rate of one foot every six days.” Water from Lake Powell serves electrical and water services to Utah, Colorado, Arizona and New Mexico. Thus the reduction in water supplied from Lake Powell to Lake Mead, means that the states served by Lake Powell are low on water too.
One additional source of water for California is ground water, but digging wells can be very costly and already, ground water in some regions of the Southwest has become as challenging to tap as any other source of water. But water wars have started and often play out locally, such that we hear very little about them unless a radical form of hostility breaks out.
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