Everything you want to know about California’s drought (except when it will end).

Summary: For decades scientists warned us that the American southwest had experienced long brutal droughts. We did nothing to prepare. Now we reap the consequences, as California experiences the worst droughts of the past century. With no end in sight, we must mobilize to mitigate the damage. Which might prove severe. This can become a blessing, if we learn from it. While we bicker about the climate change in 2100, which depends on innumerable and unknowable factors (how much coal will we burn?), scientists warn us that we’re unprepared for the inevitable occurrence of past extreme weather.  Katrina and Sandy were normal, as is this drought. More exciting weather is coming.

Click here to see the updated version of this post as of 14 March 2015!

“We don’t even plan for the past.”
— Steven Mosher (member of Berkeley Earth; bio here), a comment posted at Climate Etc.

Contents

1. The California drought: it’s bad
2. Climate Science gives us worse news
3. About this & past California droughts
4. Useful Sources of Information
5. For More Information
6. The Hydro-Illogical Cycle

(1)  The California drought: it’s bad.

It’s bad, with no end in sight.

1. “California Facing Worst Drought on Record“, NOAA, 20 January 2014.
2. “California breaks drought record as 58% of state hits driest level“, Los Angeles Times, 31 July 2014.
3. “Groundwater: California’s big unknown“, NOAA, 27 August 2014 — We’re in trouble if that starts to run out.

How bad is it? Let’s look at the past year (the California “water year” runs from October to September). The average is 23″; 1924 was the driest year at 9″; the last 12 months was 12″. Six of past 8 years were dry. The new “water year” started in October a little dry: 0.7″ vs average of 1.2″. But not as bad as 1917 – 1934: a 17 year-long period with only one year of ab0ve-average rainfall (including the record low of 1924)! Click all images to expand.

Do we all share the pain? Not equally. California is like that.

But precipitation is just one factor that makes a drought. Temperature also has a large effect on the soil. Hence the creation of sophisticated indexes to measure droughts, such as the Palmer Drought Severity Index and the Standardised Precipitation-Evapotranspiration Index (SPEI). Rainfall in California has been low, but not unusually so (as climate goes). But it’s warm, and so the drought indexes are at their lows for the past century.  Some ignored this factor, as in this article at Watts Up with That, which opens with a map of the Palmer Index for California, then ignores that — concluding that the experts cited in the above articles are wrong, and describing this as the worst California drought on record is a “wildly incorrect statement that seems focused on creating public panic.”

Now for the very bad news.  This year has been bad, but drought’s impact increases over time. And this drought is in its third year (see this graphic from the US Drought Monitor showing the increasing severity). Here is the 36 month SPEI back to 1895, from NOAA, 13 November 2014:

The dryness and heat has been especially intense over California. The last 36 months (November 2011-October 2014) has been the driest and warmest such 36-month period on record. This combination has resulted in the most extreme 36-month SPEI on record. By this measure, the current drought is the most severe drought for California in the last 120 years.

(2)  Climate science research gives us worse news.

As usual here, I let scientists speak for themselves. These are articles are an antiode to the confident assertions of climate activists that blame all extreme weather on climate change, such as “The Crisis Over California’s Water“, Joshua Frank, Counterpunch, 21 November 2014 (citing 2 scientists’ theory does not make it fact, especially for historically common phenomena; also note the implication that all climate change is anthropogenic). Red emphasis added to the interesting parts.

(a)  “Long-Term Aridity Changes in the Western United States“, Edward R. Cook et al, Science, 5 November 2004 — A mildly stated conclusion:

If the Z-C modeling results hold up, it is plausible that continued warming over the tropical Pacific, whether natural or anthropogenically forced, will promote the development of persistent drought-inducing La Nina–like conditions. Should this situation occur, especially in tandem with midcontinental drying over North America, the epoch of unprecedented aridity revealed in the DAI reconstruction might truly be a harbinger of things to come in the West.

The Colorado River Compact, allocating the water, was negotiated in 1921 — near the wettest time during the past 1,200 years.

(b)  “North American drought: Reconstructions, causes, and consequences“, Edward R. Cook et al, Earth-Science Reviews, March 2007 — In this later paper, Cook et al give us the long-suspected bitter news. Excerpt from “conclusions”:

These reconstructions, many of which cover the past 1000 years, have revealed the occurrence of a number of unprecedented megadroughts over the past millennium that clearly exceed any found in the instrumental records since about AD 1850, including an epoch of significantly elevated aridity that persisted for almost 400 years over the AD 900-1300 period. In terms of duration, these past megadroughts dwarf the famous droughts of the 20th century, such as the Dust Bowl drought of the 1930s, the southern Great Plains drought of the 1950s, and the current one in the West that began in 1999 and still lingers on as of this writing in 2005.

… The extraordinary duration of past North American megadroughts is difficult to explain, but climate models strongly point to tropical Pacific Ocean SSTs {sea surface temperatures} as a prime player in determining how much precipitation falls over large parts of North America.

(c)  Unfortunately, climate models are not yet able to give reliable forecasts for regional precipitation (they do neither well):  “The Key Role of Heavy Precipitation Events in Climate Model Disagreements of Future Annual Precipitation Changes in California“, David W. Pierce et al, Journal of Climate, August 2013 — Open copy here. “Climate model simulations disagree on whether future precipitation will increase or decrease over California, which has impeded efforts to anticipate and adapt to human-induced climate change. This disagreement is explored in terms of daily precipitation frequency & intensity.”

(3)  Articles about this and past California droughts.

Here are excellent explanations written for a general audience.

(a)  Past droughts, an example — and warning:

1. “California drought: Past dry periods have lasted more than 200 years, scientists say“, San Jose Mercury News, 25 January 2014 — “Researchers have documented multiple droughts in California that lasted 10 or 20 years in a row during the past 1,000 years.”
2. “Could the California drought last 200 years?“, National Geographic, 13 February 2014 — “Clues from the past suggest the ocean’s temperature may be a driver.”

(b)  Water management in California

1. “Drought in the United States: Causes and Issues for Congress“,  Congressional Research Service, 12 August 2012 — What do you guess Congress did with these recommendations?
2. “California faces growing water management Challenges“, Public Policy Institute of California, January 2014.
3. “The drying of the West“, The Economist, 22 February 2014 — “Drought is forcing westerners to consider wasting less water.”
4. “It Takes How Much Water to Grow an Almond?!“, Mother Jones, 24 February 2014 — “Why California’s drought is a disaster for your favorite fruits, vegetables, and nuts.”
5. “The Dust Bowl Returns”, Blain Roberts and Ethan J. Kytle (Assoc Profs of History at CSU – Fresno), op-ed in the New York Times, 9 February 2013 — “How long can we continue to grow a third of the nation’s fruit and vegetables?”

(c)  Analysis of the drought

1. “Science linking drought to global warming in dispute“, New York Times, 16 February 2014 — “It all adds up across the Southwest to an increasingly stressed water system. That’s what they might as well get ready for.”
2. “A climate analyst clarifies the science behind California’s extreme drought“, Andy Revkin, New York Times, 6 March 2014.
3. “Clarifying the discussion about California drought and climate change“, Peter Gleick (President, Pacific Institute), Science Blogs, 6 March 2014.
4. “California Drought Is Worst Since at Least 1895, Data Shows“, Mashable, 14 August 2014.

(4)  Useful Sources of Information.

The Internet provides a wealth of information about climate. NOAA especially provides wonderful toys.

1. Make your own climate map, showing precipitation or one of the drought indexes.
2. Make your own animated climate map, showing the evolution of the drought over time.
3. NOAA’s Seasonal Drought Outlook at the Climate Prediction Center.
4. The U.S. Drought Portal — A wealth of information about past and present droughts in USA, and their impacts.
5. US Drought Monitor — U Nebraska – Lincoln and Federal Agencies — Ditto as above.
6. The California Climate Tracker — make graphs and maps of California climate data. By the Desert Research Institute.
7. Westmap — make graphs and maps of climate date. By the Desert Research Institute
8. Paleoclimate Drought Resources – “What paleoclimatology tells us about drought, from the World Data Center for Paleoclimatology”.

(5)  For More Information.

See these posts:

1. Have we prepared for normal climate change and non-extreme weather?
2. Let’s prepare for past climate instead of bickering about predictions of climate change.
3. Droughts are coming. Are we ready for the past to repeat?
4. Everything you wanted to know about California’s drought (except when it will end).

(6)  The Hydro-Illogical Cycle

From the SPEI website.