Evidence suggests California's drought is the worst in 1,200 years

December 5, 2014
Research by WHOI paleoclimatologist Kevin Anchukaitis, left, and Univ. of Minnesota assistant professor Dan Griffin has shown that the drought of 2012-2014 has been the worst in 1,200 years. They used tree-rings from centuries-old blue oak like the one pictured to provide long-term context for the ongoing California drought. Credit:Megan Lundin, Wind Wolves Preserve, Bakersfield, CA.

As 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.

Daniel Griffin, an assistant professor in the Department of Geography, Environment and Society at the University of Minnesota, and Kevin Anchukaitis, an assistant scientist at Woods Hole Oceanographic Institution, asked the question, "How unusual is the ongoing California drought?" Watching the severity of the California drought intensify since last autumn, 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.

Tree rings are a valuable data source when tracking historical climate, weather and natural disaster trends. Floods, fires, drought and other elements that can affect growing conditions are reflected in the development of tree rings, and since each ring represents one year the samples collected from centuries-old trees are a virtual timeline that extend beyond the historical record in North America.

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 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."

The results of their study are published this week in Geophysical Research Letters in the article, "How unusual is the 2012-2014 California Drought?"

Explore further: 1934 drought was worst of the last millennium, study finds

More information: onlinelibrary.wiley.com/doi/10 … 002/2014GL062433/pdf

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gkam
3.2 / 5 (9) Dec 05, 2014
Those in other states will not care until they see the price of meat, fruit, grains, and vegetables.
Wake
1.6 / 5 (10) Dec 05, 2014
This appears to be a study with well thought out science. While their findings are quite interesting from a scientific point of view don't you get the feeling that this is nothing more than trying to convince people that AGW is here?

But it the NEXT longest drought in 1200 years ago was in 1934 that sort of destroys their attempt.

Why is there no NEWS being written anymore? Only propaganda to make some sort of political point one way or another.
gkam
3.4 / 5 (10) Dec 05, 2014
There is no question it is here. This discusses some parameters of it.

"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."

Isn't that reason enough? Do we not have to prepare?
pandora4real
4.6 / 5 (5) Dec 05, 2014
"Why is there no NEWS being written anymore? Only propaganda to make some sort of political point one way or another."

Why are there so many goddamned trolls?!?

This xmas give your SO the gift of sterilization. Among the plethora of problems that come from producing so many human blanks is that they all want to BE someone. Hence, the rise in sadistic trolls that see issues as a way of creating an ego identity.

The tragedy is for nature. Humans can get what they've got coming and societal breakdown won't be all bad for the environment once we start hanging those types on piano wire.
Benni
1.3 / 5 (8) Dec 05, 2014
Is that so? Worst in 1200 years, meaning this has happened before.........so what was going on at that time that it was as bad or worse and how did it get fixed back then? Maybe there's an unaccounted "orbital wobble" in here somewhere.
sparkynull
1 / 5 (6) Dec 05, 2014
Interesting article until they jumped to the conclusion that it's "human-wrought changes" causing this climate change. I found it interesting that another article on this site "Tree rings reveal nightmare droughts in the West" also discusses prolonged drought and how it is not an unusual occurrence yet doesn't try to push the climate agenda.
zz5555
5 / 5 (9) Dec 05, 2014
Interesting article until they jumped to the conclusion that it's "human-wrought changes" causing this climate change.

Can you point out where they claim that human-wrought changes are causing the drought? They do say that human-wrought changes are making the drought worse, but I can't find a place where they lay the blame for the drought itself on humans.

And why would anyone be surprised that "human-wrought changes" are making the drought worse? One of the main causes of drought is heat, and since AGW causes temperatures to rise it would be surprising indeed if AGW didn't exacerbate any drought that occurs.
MandoZink
5 / 5 (7) Dec 06, 2014
I think the phrase "try to push the climate agenda" pretty much explains the mindset behind the fractured misunderstandings in sparkynull's comment.

He apparently also didn't care that the drought-affected area of California is influenced by entirely different weather systems than the Wasatch Front / Weber River Basin chronicled in the "Tree rings reveal nightmare droughts in the West" article. The 500+ miles of intervening landscape includes both the Sierra Nevada's and the entire Great Basin.

That's like like comparing weather/climate in extreme western Kentucky to that of Charleston, South Carolina. Same distance and long/lat offset. A long-term effect in one area is not a good comparison to another locale both far away and under completely different patterns of weather.

Finding these articles "interesting", as was stated, is not the same as understanding and comprehending their implications.
Osiris1
2.3 / 5 (3) Dec 06, 2014
If we are in for problems of the water kind, in spades--then prepare. We can! We in California have in reality an unlimited supply of water, except that it is salty sea water. The Pacific ocean is our west coast. Why not build LOTs of solar powered desalinization plants all along our coast, big ones. Build enough to duplicate the expected rainfall in 'normal' years, so whatever drought comes, our crops are guaranteed. Comes with a caveat though, a freeze on new home construction in southern California would stop rampant growth that continually trumps any effort to catch up with needed water supply. Also a LOT of desert would have to be under photovoltaic collectors. This begs a command decision: the survival of which is more valuable, humans or obscure insects or birds with no more value than as curios that could be preserved in zoos. That judgement made in favor of human life, obstructionist economic saboteurs could be jailed and projects moved forward.
mbee1
1 / 5 (4) Dec 06, 2014
there is a tiny problem,it is currently raining and flooding in the state so the drought may very well be out. It does not rain much in California in the summer so anytime it stops raining before Feb, you are in a drought which is what happens every freaking year in the state. What they are complaining about is the rain before than was smaller than they want since the population of the state doubled since 1970 without a single new source of water being built. On top of that a lot of farmers in the southern part of the sacramento valley planted tree crops and grape crops which required a lot of water, all surplus water in prior years, no surplus this year so those farmer had a problem self created.
Vietvet
4 / 5 (8) Dec 06, 2014
@mbee1

"there is a tiny problem,it is currently raining and flooding in the state so the drought may very well be out."

Another example of your ignorance and stupidity.
richard_f_cronin
1 / 5 (6) Dec 06, 2014
97 % of Climatologists agree. Not all scientists. Although the American Geophysical Union still supports AGW, many more independent Geoscientists and Paleoclimatologists are seeing things differently. I would ask readers to thoroughly examine reports you read and consider that the same effects could just as well be due to geothermal heat. Kilometer thick land-based glaciers sloughing off the Antarctic land mass due to geothermal heat ( Studies of Thwaites glacier, Univ. Texas Austin). 1200 year record drought is a long time ago; say, the early 800s. Wouldn't that be the early part of the Medieval Warming Period ( 800 to 1400 AD) ? The mass of our atmosphere is one millionth of the total mass of the Earth. CO2 comprises 4 % of the atmosphere, and we're worried about 100 ppm, perhaps 200 ppm of CO2.
runrig
5 / 5 (7) Dec 06, 2014
Mr Cronin.
You are right so say the Thwaites glacier has geothermal acting at it's base.
see:
http://phys.org/n...mal.html

However as this is the first study of this kind, who's to say how long this has been going on. a decade or centuries? And one glacier is hardly the whole of the WAIS.

Also the rise in the major GHG in our atmosphere that is controllable by mankind, CO2, has been 120ppm - a 40% rise. It is irrelevant that it is just 0.4% of the atmosphere as ~ 99% of it is transparent to terrestrial IR. That makes CO2 VERY important and indeed the control knob of it's temperature once solar is absorbed. Sorry empirical science has known about this for ~150 yrs. It's not up for debate.
zz5555
4.5 / 5 (8) Dec 06, 2014
I would ask readers to thoroughly examine reports you read and consider that the same effects could just as well be due to geothermal heat. Kilometer thick land-based glaciers sloughing off the Antarctic land mass due to geothermal heat ( Studies of Thwaites glacier, Univ. Texas Austin).

Did you read that study? It shows that the geothermal heat is much less than the additional heating coming from anthropogenic changes. As the lead author says:
"The fastest glacial changes are happening where the ocean is warmer," Schroeder said. "Geothermal heating is not enough by itself to have caused the observed changes."
In response to those who are using his study to deny climate change, Schroeder confirmed that volcanic activity is not the dominant force of ice loss and rising sea levels.
(https://news.vice...ice-caps )

Other studies confirm this.
mvogell
5 / 5 (3) Dec 06, 2014
"It's not up for debate."
EVERYTHING is up for debate now because everyone thinks they are an expert and people who deal with these issues as a profession are either morons or bought off. Thankyou internet!, you've given everyone the platform to tell others how smart they are and how stupid everyone else is.
cantdrive85
1 / 5 (8) Dec 06, 2014
The sky is falling, the sky is falling...

Although the sky must have fallen before, about 1200 years ago. The sky keeps falling...
thermodynamics
5 / 5 (6) Dec 06, 2014
CantThink85 said:
The sky is falling, the sky is falling...

Although the sky must have fallen before, about 1200 years ago. The sky keeps falling...


This comes from the person who thinks the stars are driven by electricity. I think that his belief in the electric universe puts his understanding of physics in the proper perspective.
HANAMAN
1 / 5 (4) Dec 06, 2014
U have Lived in central california all my life and at 65 have seen many droughts. It is not a uncommon occurance here. In fact it seems to be the norm every 7 years or so. Of course some are worse than others. I am also a pragmatic man and realize humans have to have some impact on the global landscape. I only ask one thing...can we please have competing scientist that are knowingly predisposed to an outcome do the work. At least we would know where their hearts lie. Two professors from a liberal school in Minnesota does not surprise anyone of the final analysis. let the games begin.....
zz5555
5 / 5 (7) Dec 06, 2014
I only ask one thing...can we please have competing scientist that are knowingly predisposed to an outcome do the work. At least we would know where their hearts lie. Two professors from a liberal school in Minnesota does not surprise anyone of the final analysis. let the games begin.....

What makes you think that a professor at UMinn is liberal? My grad school was generally considered liberal, but many professors, especially in science, were quite obviously conservative. The correct way to refute science is to refute science, not make assumptions about the scientists' politics and ignore the science.

Besides, known skeptics have looked at climate science before and failed to find a problem. The fake skeptics then ignore the results - not because the scientists weren't conservative (because they were), but rather because the fake skeptics didn't like the results.
ROBTHEGOB
1 / 5 (7) Dec 08, 2014
Sun comes up, sun goes down. Sun comes up again. Adapt or die. Get over it; we can't and don't control the movement of the planets, which is what is really causing climate change. Nothing new here, move along.
thermodynamics
5 / 5 (5) Dec 08, 2014
Robthegob said:
Sun comes up, sun goes down. Sun comes up again. Adapt or die. Get over it; we can't and don't control the movement of the planets, which is what is really causing climate change. Nothing new here, move along.


Can you please give us a peer reviewed reference that shows this is the case? All the peer reviewed references I have seen say that man made CO2 is the culprit. Please give me the peer reviewed reference that says that is not the case. Here is a good reference that Captain Stumpy uses that says that CO2 is the cause:

http://www.scienc...356.full

Please show your references that say otherwise
DutchWayne
1 / 5 (3) Dec 08, 2014
Worst in 1200 years. That means there is a worse drought within the life cycle of something alive in California and it means it has happened before under the normal climate cycle. What happened 1200 years ago? In Europe and I believe in China, the climate began to warm beginning an upward climate swing that continued until the early 1300's, followed by the little ice age. Also know as the pre-industrial world. This only further documents the natural up and down cycle of the earth.

What has changed? How about a massive influx (legal and illegal) of tens of millions of people into a desert who are stripping water from the interior and moving it to the coast. I would like to see the 97% of climatologists explain how that has no impact.
zz5555
5 / 5 (3) Dec 08, 2014
Worst in 1200 years. That means there is a worse drought within the life cycle of something alive in California and it means it has happened before under the normal climate cycle. What happened 1200 years ago? In Europe and I believe in China, the climate began to warm beginning an upward climate swing that continued until the early 1300's, followed by the little ice age.

So if I understand you correctly, you believe that a warming climate can make a drought more serious. Sort of like the warming that is happening now and known to be caused primarily by humans. So that means you must agree with the article that global warming, as caused by humans, can make a drought more serious - just like when the warming was caused by natural events.

Note: Just because a very bad thing can happen naturally that doesn't mean that same bad thing suddenly becomes no problem when we cause it to happen.
Forestgnome
1 / 5 (3) Dec 08, 2014
Drought is easily measured. You measure precipitation. If tree ring data surprises them, then it sounds like it doesn't correlate well with the precip data, which means it brings into question tree ring measurements altogether. Maybe they're not as accurate as they thought they were for gauging historical data. Surprising results are often warning signs a measurement is questionable.
runrig
5 / 5 (3) Dec 08, 2014
Nothing new here, move along.


Yes please do

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