Saturday, December 15, 2012

Food for thought

Greetings Peaksters

       Here's an interesting article about the future of the Colorado River.   The river that serves the southwest and parts of California  an area that accounts for 15% of the US crops.  Annual flows could drop 20 percent by mid century.  (see below).

    By then, of course, there will be a great need for water.  The West will already be very parched.    For instance, check out these maps from a 2010 study by National Center for Atmospheric Research (NCAR) .  They are pretty mind blowing.   By 2060,  agriculture appears nearly impossible in most of the US.

     As you can see,  the US won't be alone. Unfortunately we won't have to wait until 2060.   In fact the  UN  is already warning of a looming worldwide food crisis in 2013     Besides the US.  Australia, Canada, and even Europe, major food producers, are predicted to be hit severely
For a more thorough look,  check out Stuart Saniford's Future of Drought series


Look at the maps close up here -here
The National Center for Atmospheric Research (NCAR) recently published a report modeling drought severity at the global level over the remainder of this century.  The horrifying results are shown below in Figure 1. 

Figure 1:  Dust Bowl Nation:  NCAR modeling of Palmer Drought Severity Index (PDSI) for the 21st century under a scenario where CO2 reaches 520 ppm by 2050 (--a plausible 21st century CO2 level with near-term economic collapse and positive climate feedbacks).  A PDSI index exceeding -3 (cherry red) is ‘severe drought,’ while an index exceeding -4 (brick red) is considered ‘extreme drought’.  For context on PDSI values: during the Dust Bowl decade, the US Great Plains briefly spiked to a drought severity index of -6 (purple), but rarely exceeded -3 (cherry red).  Source:  (Click on the map within this link to get a close-up on the US)
OK, so how can we interpret this map?  Well, the ‘reddening’ of the continental US shows that we’re certainly on tap for some serious drying out over the coming century, but just how bad is it projected to get?  Namely, what does a PDSI index of -3 (cherry red) or worse over the majority of the nation by the 2060s signify?

To gauge the danger illustrated in the NCAR drought map, let’s look at a PDSI reconstruction of the Great Plains over the past century – which includes the Dust Bowl decade of the 1930’s.  See figure below:
Figure 2.  Dust Bowl Drought Index.  Palmer Drought Severity Index (PDSI) graph of Great Plains 1900-2000, including the Dust Bowl decade of the 1930s.  Source:
Note that, during the 1930’s Dust Bowl in Figure 2, the PDSI briefly spiked to -6, but otherwise rarely dipped below -3.  Also note the PDSI moving average (smooth black line) does not exceed -3.  Thus, the monumentally destructive Dust Bowl drought represented ‘merely’ a less-than-a-decade stretch of PDSI right around -3.  And if you want a feel for what this looks like in real life, see Ken Burns’ Dust Bowl documentary:  Maybe also dig out that old copy of Steinbeck’s Grapes of Wrath. 
The take-home lesson?  An decade-long PDSI of -3 will kick your ass.  It will kick you off the land. 
Now compare the Dust Bowl PDSI levels of around -3 to the NCAR projections for the US in the 2060s.  An appropriate response to the juxtaposition of the two graphs is “What the #*&%?!”  The continental US becomes agricultural train-wreck, with perhaps over 80% of the country mired in severe drought (exceeding -3) or worse, including the Midwestern agricultural heartland.  Fully half of that drought-stricken 80% features unholy drought levels from -4 to -10.  


Will the West ever solve its water woes?

Congress isn’t planning to take action on climate change any time soon. But if the planet keeps warming, a number of states won’t be able to ignore the problem quite so easily. One good place to see this is in the Colorado River basin.

The Colorado River’s Horseshoe Bend, in Page, Ariz., in March 2008. (Matt York/AP)
The Colorado River provides fresh water to nearly 40 million people in seven states out west: Arizona, California, Nevada, Colorado, New Mexico, Utah and Wyoming. A sizable chunk of U.S. agriculture relies on that water — about 15 percent of the nation’s crops and 13 percent of its livestock. (Indeed, the vast majority of the river’s water is used for irrigation and agriculture.)
But there’s a problem: The Colorado River may soon no longer have enough water to satisfy the region’s needs. Thanks to rapid population growth in cities like Las Vegas and Phoenix, water demand is surging. Meanwhile, the supply of water is dropping — and could keep dropping as climate change speeds evaporation, shrinks the snow pack in the Rocky Mountains, and makes droughts more likely. By some recent estimates, annual flows could drop up to 20 percent by mid-century.
The dilemma is laid out in a big new report from the U.S. Bureau of Reclamation, looking at the future of the Colorado River. The chart below sums things up. The authors of the study took the best estimates of future population growth in the region and paired them with estimates of future water supply. Trouble ensues:
There’s a fair bit of uncertainty here — climate models still disagree on how sharply annual flows will drop in the future. And population growth is hard to predict. Some environmental groups have even suggested that states might be exaggerating their projected growth to qualify for more federal money for big infrastructure projects.
That said, the best estimates suggest that demand will continue to outstrip supply, much as it has in the past decade. By 2060, the report says, the median shortfall could reach 3.2 million acre-feet (or about five times as much water as Los Angeles uses each year). The amount of irrigated farmland is also expected to shrink.
When scientists talk about the need for “climate adaptation,” this is what they mean. So how are these states going to deal with the water problem? The report has an in-depth analysis of different adaptation options, grouped into a few broad categories:

Our savior! (3-D rendering courtesy Dassault Systemes)
–Importing water from elsewhere. The report examined a bunch of zany proposals for bringing more water to the basin. One idea is to build a massive 600-mile pipeline from the Missouri River down to Denver. Sure, it would cost many billions of dollars and require large new power plants to pump the water, but why not? Or maybe ships could tow freshwater icebergs from the Arctic down to Southern California! Sadly, the report concluded that many of these schemes are unfeasible for now.
–Desalination. Another idea: If the fresh water’s running out, why not set up some desalination plants to treat brackish water or seawater? There’s already a $150 million desalination plant operating in Yuma, Ariz., to recycle salty irrigation water. The report doesn’t rule this out, though these plants are pricey and would likely only be built in severe shortages. (What’s more, desalination plants use a lot of energy, which means more carbon emissions, which worsens the problem… )
–Conservation and reuse. This is the option environmental groups tend to prefer, and there are dozens of different strategies here. Cities can recycle their “grey water,” (say, using old bathwater to flush toilets or water golf courses). Land managers could kill off thirsty plant species like thetamarisk. Water managers could slow the pace of evaporation by placing covers over reservoirs and irrigation canals. Governments could even set up a system in which users trade water permits.
Add it all up, and the report concludes that there are probably enough realistic water-saving strategies out there to make up for the projected shortfall in the next 50 years. That’s the good news. 
The bad news is that none of this is cheap or easy. Right now, a city like San Diego pays about $800 for an acre-foot of water from the Colorado River. But desalinated water would cost up to $2,150 per acre-foot, according to the report. Recycling waste water costs up to $1,800 per acre-foot. Covering irrigated canals? As much as $15,000. That’s one reason why state and local authorities have often resisted drastic measures.
What’s more, the report notes, even if the right mix of adaptation strategies were adopted, the Colorado River Basin would still be highly vulnerable to droughts and water shortfalls in a certain portion of years. There’s no way to stave off all possible calamities.
Further reading:
— Perhaps the best book on the history of the American West’s water woes (and a look at how states have tangled over water rights) is Marc Reisner’s “Cadillac Desert.” 
— Note that shortages are already occurring in many places. Las Vegas has been grappling with this issue since 2009, spending billions on new pipes into Lake Mead and forming “wastewater patrols.”
— My colleague Juliet Eilperin recently looked at how low levels in the Colorado River affect power plants: “In the Colorado River’s 100-year recorded history, 1999 through 2010 ranks as the second-driest 12-year period, yielding an average of 16 percent less energy.”


Post a Comment

Subscribe to Post Comments [Atom]

<< Home