Saturday, December 6, 2014

The Californian drought is the worst in 1,200 years

Sou | 9:40 PM Go to the first of 31 comments. Add a comment

According to research carried out by Daniel Griffin from the University of Minnesota and Kevin Anchukaitis from Woods Hole Oceanographic Institution, the current drought in California is the worst in at least 1,200 years.

Here is the latest drought update for California from the US Drought Monitor, which wouldn't include the recent rain. It's for the 2 December - four days ago.

Source: US Drought Monitor

From what I read, it will take quite a bit more than this week's downpours to lift California out of its drought.

In a paper just published in Geophysical Research Letters (GRL), Drs Griffin and Anchukaitis found that this Californian drought was the most severe drought going back at least 1200 years. The abstract:
For the past three years (2012-2014), California has experienced the most severe drought conditions in its last century. But how unusual is this event? Here we use two paleoclimate reconstructions of drought and precipitation for Central and Southern California to place this current event in the context of the last millennium. We demonstrate that while 3-year periods of persistent below-average soil moisture are not uncommon, the current event is the most severe drought in the last 1200 years, with single year (2014) and accumulated moisture deficits worse than any previous continuous span of dry years. Tree-ring chronologies extended through the 2014 growing season reveal that precipitation during the drought has been anomalously low but not outside the range of natural variability. The current California drought is exceptionally severe in the context of at least the last millennium and is driven by reduced though not unprecedented precipitation and record high temperatures.

The press release is at Science Daily. Here are some excerpts:
California finally experiences the arrival of a rain-bearing Pineapple Express this week, two climate scientists from the University of Minnesota and Woods Hole Oceanographic Institution have shown that the drought of 2012-2014 has been the worst in 1,200 years...
...they wondered how it would eventually compare to other extreme droughts throughout the state's history.
To answer those questions, Griffin and Anchukaitis collected new tree-ring samples from blue oak trees in southern and central California. "California's old blue oaks are as close to nature's rain gauges as we get," says Griffin. "They thrive in some of California's driest environments." These trees are particularly sensitive to moisture changes and their tree rings display moisture fluctuations vividly.
As soon as the National Oceanic and Atmospheric Administration (NOAA) released climate data for the summer of 2014, the two scientists sprang into action. Using their blue oak data, they reconstructed rainfall back to the 13th century. They also calculated the severity of the drought by combining NOAA's estimates of the Palmer Drought Severity Index (PDSI), an index of soil moisture variability, with the existing North American Drought Atlas, a spatial tree-ring based reconstruction of drought developed by scientists at Columbia University's Lamont-Doherty Earth Observatory. These resources together provided complementary data on rainfall and soil moisture over the past millennium. Griffin and Anchukaitis found that while the current period of low precipitation is not unusual in California's history, these rainfall deficits combined with sustained record high temperatures created the current multiyear severe water shortages. "While it is precipitation that sets the rhythm of California drought, temperature weighs in on the pitch," says Anchukaitis.
"We were genuinely surprised at the result," says Griffin, a NOAA Climate & Global Change Fellow and former WHOI postdoctoral scholar. "This is California--drought happens. Time and again, the most common result in tree-ring studies is that drought episodes in the past were more extreme than those of more recent eras. This time, however, the result was different."
While there is good evidence of past sustained, multi-decadal droughts or so-called "megadroughts"' in California, the authors say those past episodes were probably punctuated by occasional wet years, even if the cumulative effect over decades was one of overall drying. The current short-term drought appears to be worse than any previous span of consecutive years of drought without reprieve.
...So what are the implications? The research indicates that natural climate system variability is compounded by human-caused climate change and that "hot" droughts such as the current one are likely to occur again in the future. California is the world's 8th largest economy and the source of a substantial amount of U.S. produce. Surface water supply shortages there have impacts well beyond the state's borders.
With an exceptionally wet winter, parts of California might emerge from the drought this year. "But there is no doubt," cautions Anchukaitis, "that we are entering a new era where human-wrought changes to the climate system will become important for determining the severity of droughts and their consequences for coupled human and natural systems."
I didn't cut much. You can read the full press release here at ScienceDaily.com.

From the WUWT comments

Despite getting a lot of publicity in the mainstream media, this research hasn't been featured at WUWT so no comments today. It's probably too inconvenient or else Anthony hasn't got around to copying and pasting it under a "claim" headline. Anthony doesn't much like to write about climate change and his home state. However you may recall he has posted a couple of previous articles trying to downplay the severity of this most recent Californian drought, such as here and here.

Daniel Griffin, Kevin J Anchukaitis. "How unusual is the 2012-2014 California drought?" Geophysical Research Letters, 2014; DOI: 10.1002/2014GL062433


  1. Its probably not in the best of taste, however, given that deniers like to snigger at the 'Gore Effect', every time a public appearance by the Oscar and Nobel winning ex-VC coincides with a cold snap, it is tempting to derive some ironic amusement the co-location of the world's leading denier site with record aridity unprecedented in a millenium?

    Watt's Warmth anyone? ;-)

    1. I echo your sentiment, Phil - and don't worry, WUWT-ers are an uncouth lot and don't know what good taste is.

      It's not just drought not seen for more than a millenium, but record heat in the instrumental era too.

  2. In what is hopefully not a total fluke of weather, right now here in the land of fruits and nuts it's looking like the beginning of Noah's flood.

    1. Brandon, it's good that the rain is finally pouring down, but a shame it has to come with such a vengeance - flash floods etc. I hope most of it sticks and fills up the dams, rather than flowing into storm water drains and the sea.

      We've been getting more than our share of storms here these past few days, too. Which is a bit strange, given the almost El Nino. That usually means drier than normal weather here.

    2. The recent rains raised the California reservoir levels by less than 1 percent

    3. Shasta was up 2%, Oroville up 5% last week; the 2 biggest.

      Daily Reservoir Storage Summary

      California’s holiday gift: forecasts of a wet winter
      Kurtis Alexande, San Francisco Chronicle
      Updated 9:40 am, Saturday, December 6, 2014
      Meteorologists say periodic showers are likely through the middle of December, while new federal climate models, including a bumped-up forecast for El Niño, hint at definitively soggier months ahead.


      my area
      North Coast stream flows above normal
      Area retains exceptional drought designation

      Stream flows are running above “normal” in the region following the series of storms during the past week. The Thanksgiving storms dropped .92 inches on Nov. 28; .80 on Nov. 29; .72 on Nov. 30; .04 on Dec. 1; .88 on Dec. 2 and 1.36 on Dec. 3 in the Willits area. Since Oct. 1 area rains are “normal” based on 102 years of data


      Experts don’t think the drought can be broken in one year. Rat saw it happen in ’78.

      Wharf Rat

    4. Here's is a good summary of the reservoirs. You can change the date.


      Too bad they don't give an overall percentage. Once could figure it out by weighting the reservoir capacity.

  3. Thanks, Sou. Yes, there have been flood warnings but so far no landslides in my area that I've heard of. Some areas got hail two nights ago, we only got thunder ... rare treat to me having grown up where that's more common than here. I too hope our water management crews are on top of capturing as much of it as they can. Mostly though it feels and sounds like a mostly normal winter. Which is strange.

    Whatever funky state ENSO and PDO are in appears to be working out for the both of us, so cheers and stay dry. :)

    1. My biggest shock upon moving to California what that after a month or so there, there was a thunderstorm. Ho hum, whatever, normal occurrence everywhere I'd lived (or lived since).

      The Merc and the Chron the next day had it on their front page -- "The biggest thunderstorm since the thunderstorm of '77" one of them blared.

    2. Was that the one about two years ago? I experienced that one from inside an airplane coming in from Chicago. First and only time I've been in an aircraft struck by a bolt of lightning. It was rather thrilling, but I must say I would have appreciated the light show from the ground instead. The photos were incredible.

    3. September 8, 1999 apparently. The headline must have been in the Chron. The Merc has archives available online (the chron wants you to pay even just to search); the two articles listed there are a bit less dramatic.

    4. Oh yeah, '99. F0 tornado formed briefly over Richmond. That was a really wet winter in general. I-880 got so flooded that my normal 45 minute commute to work took 2+ hours.

  4. The WHOI page has pretty pictures on top of the text:

  5. An interesting comment in Eric Worrall's enthusing over Steve Mac's supposed takedown of the Sheep Mountain chronology. SM comments archly:

    "this comment has very little to do with my post at Climate Audit. Nor is “Mike’s Nature trick” relevant to the topic discussed at CA. Nor has Mike’s Nature trick been correctly described in the above article."
    By "this comment" he means the post.

    1. Thanks, Nick. I had to go out for a bit and just before I left I noticed Eric's article. I couldn't fathom what he was going on about, especially with post-1980 trees somewhere and Michael Mann's paleo reconstructions. AFAIK there have been a few thermometers about the place since the 1980s so we don't need to rely on trees to tell us what's happening to the temperature.

      Not that I'd take Steve McIntyre's word for anything but it's fun to see him put Eric in his place (as dunce of the class) :)

      I'll go back and see if I can figure out what the fuss is all about.

    2. I've had a peep at CA. Seems to me that Steve's audience has declined a lot - or maybe not. I've never bothered with him much. But when you've got ignoramuses like Eric Worrall, Ferdberple, Anthony Watts, the Scottish Sceptic and Wondering Willis making inane comments, it speaks volumes. And Steve himself wanting a rewrite of a paper published 16 years ago, to include data beyond the period looked at - that spells weird.

      CA is so far past its use-by date. Even years ago when some might have considered it "fresh", CA smelt off. These days it seems to be vying with WUWT to see which is the nuttiest denier blog.

      For anyone who's curious you can read the WUWT article here:


      And the CA article here:


      In the latter archive you can witness Steve McIntyre going nuts (ie losing it, going off his rocker) doing a Christopher Monckton with Nick Stokes - the only thing he's missing is the threat of legal action. Nick remains cool as a cucumber as usual :)

    3. It's hard to grasp through all the invective, but in that thread is the auditor trying to claim that there is no temperature station that diverges from the NH mean, so therefore Nick's example is wrong? And then he and Mosher proceed to dispute every example Nick gives?

      That's some heady kool aid they're drinking...

    4. The way I read it, McIntyre accused Stokes of "making stuff up once again" without bothering to consider that out of all the jillions of stations out there, surely at least one of them had diverged from the hemispheric average. I see it all the time. Contrarian makes an easily refutable factual error in knee-jerk reaction, then splits hairs or tries to reframe the original argument when shown to be thoroughly incorrect. It's not kool aid so much as not able to afford being seen as wrong because ... well ... when one is wrong, one always has to be right.

    5. Sou, "But when you've got ignoramuses like Eric Worrall, Ferdberple, Anthony Watts, the Scottish Sceptic and Wondering Willis making inane comments, it speaks volumes."

      Even before I read your comment, I was struck that WW&W were more participatory on the CA thread than they are at WUWT which I'd think is more their home turf ... most obviously for Anthony. Like you I don't keep close tabs on CA, so I don't know if that's an anomaly or not. It's almost as if WUWT is in this bizarre state of being full-on denier central, but the larger players mostly use it for a bully pulpit but go elsewhere for talking shop.

      The more I think about it, the more curious, and amused, I become.

    6. It strikes me that they are trying to appear knowledgeable when they don't have a clue what they are talking about.

      Recall when Anthony relied on not one but two tree ring studies (including Colorado and one solely in Utah!) when trying to play down the current Californian drought.


      What a hypocrite, when at CA he wrote, obviously without understanding a thing about the subject:

      "This is quite possibly the most definitive thing I’ve ever seen published on tree ring proxies. It’s vindication and falsification all in one. The out-of-sample issue is indeed devastating as Richard Drake points out."

      Vindication of what exactly? Falsification of what? "Out of sample issue" does he even know what he means? I doubt it. I think he throws about words like "devastating" much the same way he throws about words like "mendacious" and "hate" whenever he finds someone writing science, which he really, really doesn't like.

    7. It's weird isn't it? First he jumps on Nick for the quite reasonable point that some stations must diverge from their average (or else, why would you need the average, you muppet?!), and then when he realizes he's been pwned, he then points out that Mann claimed this station was a "sweet spot", therefore Stokes must also disagree with Mann - which would only be an issue if McIntyre was as wrong as Mann. Incredibly pig-headed behavior.

      He's obviously been caught out in that post - I guess when your whole career is built on constructing cheap internet gotchas, you get really pissed when someone does it back to you ...

    8. Sou, re: tree rings. Classic confirmation bias at its finest. Trust the data when it tells the proper story, not only arbitrarily discard it but stomp its living guts out and the researchers who gathered it when it doesn't. Here's one from dbstealey yesterday on the Friday Funnies thread: "Where did you get your chart? What is the provenance? Because it seems to contradict WoodForTrees database. Everyone accepts WFT. Why should we accept something that contradicts it?"


      For the record, I got my data from HADCRUT4. It "contradicts" WFT because I used data prior to 1979.

      I think Anthony understands McIntyre's argument which, if I understand correctly, is that if the latter years of the tree ring proxies diverge from the instrumental record, we can't rely on them for anything prior to that either. Not an entirely horrible argument on the face of it, except at WUWT "everyone accepts" that the WMP was warmer than today because of ... tree rings. And Vikings in Greenland. It gives me a devastating headache on their behalf.

      Captain Flashheart,

      I often wonder if they realize their face is planted on the floor because they've tied their own shoelaces together. And yeah, we're on the same wavelength: when you professional trade on picking nits instead of actually producing novel research it's gotta be tough to realize everyone else can see your own fleas.

      "You muppet" was a nice touch. Thanks for that.

    9. If I was pushing the lukewarmer pea across the table, I'd be trying very hard to get rid of the 'MWP'.

      A global, synchronous event as warm as or warmer than the present at a time when there was no major forcing change is a very strong argument for high climate sensitivity.

    10. We need to talk about Eric.

      Nick Stokes' mention of his name on this site would have been enormously gratifying (in ways we don't really want to think about) for our little Errol um.. Eric.

      "Nick Stokes has cited me, Nick Stokes has cited ME"

  6. Now -- think what California's going to look like when we get three years of _rainfall_ greater than seen in the past thousand years.

    It'll be much worse than this: http://en.wikipedia.org/wiki/Great_Flood_of_1862

    ... Central Valley Lake ...

  7. The utter wuwters are crowing over NOAA's official exoneration of AGW in the matter of CA's drought.
    Here's Michael Mann on that NOAA paper via The Huffington Post


    1. Correction: I omitted the inverted comers around NOAA's "paper"

    2. "The utter wuwters are crowing over NOAA's official exoneration of AGW in the matter of CA's drought".
      I'm sure you must be mistaken. The study was based purely on computer "modelling" which surely means the "skeptics" won't accept that as acceptable science.


    3. I just got pointed to it by a reactionary in another forum.

      The NOAA paper is all about precipitation:

      The paper in the OP mentions precipitation was not unusual; it was the combination of low precip and high temperature that led to severe drought.

  8. Let me know when the drought reaches 220 years long, then we could say its bad.


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