Noah Diffenbaugh of Stanford is a well-known source of papers claiming alarming things about weather and climate. He churns out a paper about 2-3 times a year, with the typical bent of climate change is causing “X”. This one is no different.Anthony's wrong as usual. Dr Diffenbaugh has a lot more than 2 or 3 papers published each year. Last year Google Scholar shows he had thirteen papers published.
At present 91% of California is in drought (D1 to D4, not counting the "abnormally dry" category), and less than 4% is not in drought and not abnormally dry. That's only because El Nino brought some much needed rain and snow to some of the state. California has been more in drought than not these past few years. What Anthony was protesting was a new paper in Science Advances by Daniel L. Swain, Daniel E. Horton, Deepti Singh and Noah S. Diffenbaugh. In keeping with the Serengeti Strategy favoured by climate disinformers, the only person whose name Anthony mentioned was the last-named author, Noah Diffenbaugh. That's the only person he complained about. He didn't mention the lead author, Daniel Swain, or any of the others.
Changing weather patterns in California
The paper was a follow-up to previous research relating to the California drought. Earlier research linked the drought to the "Ridiculously Resilient Ridge" - which I've written about before. From the press release for this new paper, at ScienceDaily.com:
"The current record-breaking drought in California has arisen from both extremely low precipitation and extremely warm temperature," said Diffenbaugh, an associate professor of Earth System Science at Stanford's School of Earth, Energy & Environmental Sciences and a senior fellow at Stanford's Woods Institute for the Environment. "In this new study, we find clear evidence that atmospheric patterns that look like what we've seen during this extreme drought have in fact become more common in recent decades."
In the new study, Stanford graduate student Daniel Swain and coauthors investigated whether atmospheric pressure patterns similar to those that occurred during California's historically driest, wettest, warmest, and coolest years have occurred with different frequency in recent decades compared with earlier in California's history. The study focused on the northeastern Pacific Ocean and far western North America, encompassing the winter "storm track" region from which the vast majority of California precipitation originates.
The researchers used historical climate data from US government archives to investigate changes during California's October to May "rainy season." They identified the specific North Pacific atmospheric patterns associated with the most extreme temperature and precipitation seasons between 1949 and 2015. Their analysis revealed a significant increase in the occurrence of atmospheric patterns associated with certain precipitation and temperature extremes over the 67-year period.
In particular, the Stanford scientists found robust increases in the occurrence of atmospheric patterns resembling what has occurred during the latter half of California's ongoing multi-year drought.
"California's driest and warmest years are almost always associated with some sort of persistent high pressure region, which can deflect the Pacific storm track away from California," said Swain, the study's first author and a graduate student in Diffenbaugh's lab. "Since California depends on a relatively small number of heavy precipitation events to make up the bulk of its annual total, missing out on even one or two of these can have significant implications for water availability."
Blocking ridges are regions of high atmospheric pressure that disrupt typical wind patterns in the atmosphere. Scientists concluded that one such persistent ridge pattern -- which Swain named the Ridiculously Resilient Ridge -- was diverting winter storms northward and preventing them from reaching California during the state's drought. In 2014, the Stanford researchers published findings that showed that the increasing occurrence of extremely high atmospheric pressure over this same part of the Northeastern Pacific is "very likely" linked to global warming.
The group next wanted to investigate whether the particular spatial pattern associated with the Triple R has become more common -- a question not asked in the original 2014 study. The new study provides a more direct answer to this question.
"We found that this specific extreme ridge pattern associated with the ongoing California drought has increased in recent decades," Swain said.
One interesting finding was that while there are more patterns leading to dry conditions and an increased risk of drought, there isn't a reduction in patterns associated with extremely wet conditions. From the press release:
"We're seeing an increase in certain atmospheric patterns that have historically resulted in extremely dry conditions, and yet that's apparently not occurring at the expense of patterns that have historically been associated with extremely wet patterns," Swain said. "We're not necessarily shifting toward perpetually lower precipitation conditions in California -- even though the risk of drought is increasing."
That might sound contradictory, but it's not, the scientists said. Imagine looking at a 10-year period and finding that two of the years are wet, two are dry, and the rest experienced precipitation close to the long-term average. Now imagine another decade with three very dry years, three very wet years, and only four years with near-average precipitation.
"What seems to be happening is that we're having fewer 'average' years, and instead we're seeing more extremes on both sides," Swain said. " "This means that California is indeed experiencing more warm and dry periods, punctuated by wet conditions."
A "few caveats" from Anthony Watts
Now that's interesting if a bit of a worry for people living in or depending on California weather. So what was Anthony Watts complaining about?
Well, Anthony didn't comment on any of the science that was in the paper or the press release. Either he didn't read it or, at least as likely, he didn't understand what he read. He did complain about the pictures, which is more at his level. (I once had someone complain that there weren't enough coloured pictures in scientific journals. I figured their normal reading was comics.) Anthony's complaint was that the press release about the paper had photos of dried up lakes and riverbeds to illustrate the drought. This seems to be what one of his "few caveats" referred to. (Does Anthony know what a caveat is?) Anthony would have preferred a photo of Lake Oroville full to the brim. Until January that lake was also dried up, but it has since filled with water. I don't know why he would want an article about drought to have a picture of a filled reservoir. That's a mystery that I've yet to fathom.
Next Anthony put up a chart showing major droughts in the West - not just California. That seems to be the remainder of his "few caveats". It's a favourite chart of Anthony's, which is odd because it was based on data from tree rings. Anthony Watts knows that his climate conspiracy theorists put all their faith in data from tree rings - um not! Also why Anthony would want to show a chart of the West, not just California, is a mystery. The bigger mystery though (because the West encompasses California) is why he would show a chart that only goes up to 2003. Why does he want to hide the last twelve years? (His chart is wrongly labeled too, indicating it only goes to 2000 when it should state it goes to 2003.) The answer might lie in what's happened in the last fourteen years. Not just California, but much of the West has been in drought a lot of that time.
Below is an animated chart which has the version that Anthony showed together with his notation, and on which I've marked the percentage of the West that is now in drought. The chart is based on data from Cook et al 2004 and it only goes to 2003. That means that the plot that Anthony shows doesn't include most of the current drought years.
To give you some idea of what conditions have been like since the period Anthony's chart covers, below is a chart showing the percentage of USA West that was in drought from 2000 to 2016, using data from the US Drought Monitor:
And below is an animated map just showing the pattern of drought at the end of March each year, from 2004 to 2016 - again from the US Drought Monitor:
There are many WUWT puzzles - here are two more:
- Why would Anthony Watts want to pretend that drought isn't a problem?
- Why would he not be wanting to find out more about it's causes and the likelihood of future occurrences?
It's one thing to be a climate conspiracy theorist and reject everything scientific. The fact that Anthony would rather see seas rise a couple of meters this century than accept science is one thing. However this research isn't about something that affects people far from Anthony's home (like Miami and Bangladesh sinking beneath the sea). This research is about the part of the world that Anthony and his family live in.
Doesn't he care whether he'll have water this year or next? Doesn't he care whether his home state can continue to produce food? Is denial so important to him that he'd rather see his home state dry up completely rather than consider that science might help alleviate the problem?
From the WUWT commentsMost of the people commenting seem to be not just denying science, they are denying weather. There's no drought as far as many of them are concerned. And it was hotter way back when, in their flawed memories. Just so you can compare, here is a chart of the average annual temperatures in California from 1895 to the present - from NOAA. You can see how much hotter it's been in this latest period of drought:
Compare the above with the memories of emsnews:
April 3, 2016 at 5:57 am
I grew up out there in the desert Southwest including California. The 1950’s were hot and dry! I remember the military base in the Death Valley region when I was very young. We were all warned to not stand with the sun in our face lest the heat warm our feet through the sneakers and burn our feet including, melting our shoes.
My father dug pits in the ground and covered these over for us to play in out of the hot sun! Then the 1960’s came and it was cold, cold at night to the point I bought a bunch of old fur coats from Value Village and made blankets out of these since my hippie hovel had no heating system (no one needed it during the previous 1920-1960 warm cycle!).
jim Steele is a climate conspiracy theorist who has some fantasy that it was hotter in the 1930s than the 2010s:
April 2, 2016 at 4:31 pm
Diffenbaugh is a relentless alarmist. But that is what gets funded. Diffenbaugh blamed drought on warmer temperatures but doesn’t tell you that maximum temperatures in most of California have cooled since the 1930s as shown in this published illustrations http://landscapesandcycles.net/image/103207378.png
Rising minimum temperatures have little, if any effect on drought.
There is no average precipitation in California. El Nino and La NIna cause precip to bound between extremes and there is no trend as determined by Blue Oak tree ring. http://landscapesandcycles.net/image/103367298_scaled_608x228.jpgHe's wrong. The average maximum has been a lot higher lately. (Jim did an Anthony Watts and hid the latest data. His trend map stops nine years ago, in 2007.):
As usual, various conspiracy theories are put forward. Lots of people joined Taylor Pohlman in his conspiracy theory:
April 2, 2016 at 5:04 pmNone of the little "climate hoaxers" thought to read the paper. I don't think it would make any difference. Conspiracy theorists are immune to reason. Anyway, for those of you who don't as a rule favour a conspiracy theory over a rational explanation, the authors explain their choice of period in the paper:
“Between 1949 and 2015…”. Could it be he left out the 30’s because of the ‘inconvenient’ amount of heat then? At least he has an excuse for leaving out the 1850’s, presumably lack of data, but no such excuse for bisecting the twentieth.
Whereas the NCDC precipitation and temperature data sets extend as far back as 1895, the R1 reanalysis begins in 1948, and so we restricted our analysis to the overlapping set of full October-May “cool season” periods between 1949 and 2015 (October 1948 through May 1949, October 1949 through May 1950, etc).
References and further reading
Daniel L. Swain, Daniel E. Horton, Deepti Singh, and Noah S. Diffenbaugh. "Trends in atmospheric patterns conducive to seasonal precipitation and temperature extremes in California". Science Advances, March 2016 DOI: 10.1126/sciadv.1501344
- Rise of the ridiculously resilient ridge: California drought patterns becoming more common - press release at ScienceDaily.com
- The Rise of the Ridiculously Resilient Ridge - blog article about the paper by the lead author, Daniel Swain
Diffenbaugh, Noah S., Daniel L. Swain, and Danielle Touma. "Anthropogenic warming has increased drought risk in California." Proceedings of the National Academy of Sciences 112, no. 13 (2015): 3931-3936. doi: 10.1073/pnas.1422385112 (open access)
Cook, Edward R., Connie A. Woodhouse, C. Mark Eakin, David M. Meko, and David W. Stahle. "Long-term aridity changes in the western United States." Science 306, no. 5698 (2004): 1015-1018. DOI: 10.1126/science.1102586 (pdf here)
Human influence on the Californian drought - HotWhopper article, October 2014