California dryness and recovery challenge multi-century odds

California dryness and recovery challenge multi-century odds

Between October 2011 and September 2015, California saw its driest four-year period in the instrumental record, which dates back to 1895. Parts of the state lost more than two full years of precipitation during the prolonged, severe dry spell. But, a new study by NOAA NCEI scientists suggests that from the longer-term view of paleoclimate records, the southern Central Valley and South Coast parts of the state saw their worst dry spell in nearly 450 years.

Published in the Journal of Climate , this study also looked at how long it would take the state to recover from its current deficits. And, the scientists found that California's hardest hit areas would likely need several decades for their long-term average precipitation to recover back to normal levels, starting from the 2012–2015 deficits. "The odds of the state completely recovering from its extreme dryness within two years are estimated at less than 1 percent," said Dr. Eugene R. Wahl, NCEI paleoclimatologist and lead author of the study. "But, that may be what's happening right now if very wet conditions continue into spring."

The extreme El Niño conditions between 2015 and 2016 helped jumpstart recovery in the northern half of the state. And, the scientists found that when very strong or extreme El Niño events followed a similar deep dryness, California's full recovery time was nearly cut in half. The high amounts of precipitation California has received during the current wet season have already set the state up for a faster recovery time than 80 percent of similar events. If it continues to be an extremely wet year for the state, like fall 1982 through summer 1983, California would be looking at an even shorter recovery time.

Different Strokes for Different Climate Divisions

But, different parts of the state have felt the impacts of the dryness differently, and they will likely recover at different rates. To get a better view of these regional differences, the scientists also looked at each of the seven standard climate divisions in California and their histories of extreme dry spells.

California dryness and recovery challenge multi-century odds

In most of these regions, the scientists found that similar very dry events had occurred since the late 16th century. However, two of the state's hardest hit regions—the San Joaquin Drainage and the South Coast Drainage—likely hadn't seen a four-year period as dry since at least before 1571. "These two regions include the agriculturally important Central Valley and the densely populated greater Los Angeles and San Diego metropolitan areas," said Dr. Wahl, "So, the social and economic impacts are of particular importance there."

According to analysis of instrumental data, the Southeast Desert Basin division had the highest likelihood of recovering within two years at around 4 percent. The San Joaquin Drainage and the South Coast Drainage divisions effectively had a zero percent chance of recovery within two years. And, the state's other four climate divisions ranged from a less than 0.1 percent to around a 1.5 percent chance. With the paleoclimate records, the results were similar for the Northeast Interior Basins, Central Coast Drainage, San Joaquin Drainage, and South Coast Drainage divisions. But, the likelihood of recovering within two years dropped even lower for the North Coast Drainage, Sacramento River Drainage, and Southeast Desert Basin divisions.

Megadroughts Could Be on the Way

By looking at precipitation alone, this study provides a unique view of California's past climate as well as insights into its future. Under current conditions, the scientists found that precipitation patterns alone are capable of producing unprecedented dry conditions such as occurred in the San Joaquin Drainage and the South Coast Drainage regions during 2012–2015, without the compounding factor of increasing temperatures.

In a warming world, higher temperatures could combine with and amplify severe precipitation deficits. If temperatures continue to rise as they have, the U.S. Southwest could be facing "megadroughts" —worse than any droughts in the region since medieval times—by the second half of the 21st century.

Explore further

January was wetter and warmer than average for the U.S.

More information: Eugene. R. Wahl et al. Multi-century evaluation of recovery from strong precipitation deficits in California, Journal of Climate (2017). DOI: 10.1175/JCLI-D-16-0423.1
Journal information: Journal of Climate

Provided by NOAA Headquarters
Citation: California dryness and recovery challenge multi-century odds (2017, April 11) retrieved 18 June 2019 from
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Apr 11, 2017
This article is fake news. I have records for every month of rainfall in california going back to 1850. The lowest 4 year period in state history is not 2012-2015. The period 1986–1989 had exactly the same 4 year low as this which was 63 inches. 1974–1977 had 65 inches. 1958–1961 had 57 inches. 1930–1933 62 inches. 1897–1900 65 inches. Overall average rainfall prior to 1945 was averaging 22.0 inches and after 1945 has averaged 21.7. 1945 is when CO2 emissions dramatically started spiking. After 1975 which is the period when temperatures started rising there has been an average of 22.1 inches per year. The lowest year of all was 1850 with 7.4 inches and 1897 with 9.87 inches 1975 with 8.05 inches. 2013 was the lowest recent year at 12.8 inches.

Apr 11, 2017
Rainfall where? It's a big state with a plethora of microclimates and major differences in topology.

Apr 11, 2017
A paper came out last week from NCAR that described the meteorological effect that caused the drought and is responsible for rainfall in california overall. A pattern of winds develops near the west coast of california that they called wavenumber-5. The reasons for the configuration of winds is unknown. However, when it sets up a certain way it forces almost all storms to divert from california. In other configurations such as this year it directs storms to california. So, Mr Mann was wrong to link rising temperatures to the drought. There is no evidence the configuration has anything to do with temperature.

Apr 11, 2017
Gkam its the same with temperature. In my region of the Bay Area there are 10 different wunderground weather stations including my own. They show 2 degrees difference. What is the real temperature of this area? If you have a 1000km between weather stations what is the temp of the area? Do we count the continuous average temp or the high and low and average? Do we care about the low being higher or the high being higher, the winter higher or summer? Is it the difference between low and high or the absolute temp? Is it the temp 1 meter off the sea level or the sea level, does the humidity with the temp make a difference for what we are trying to measure? The idea is so confused and imprecise mixing temps from different instrument types in different conditions. They call it a record setting drought by precisely picking a specific set of dates probably. It's not record setting partly because our records are so incomplete.

Apr 11, 2017
I understand the microclimates of the Bay Area, having done degree-day analyses in many of them for energy management tracking.

And I grew up in the Central Valley and lived in the desert for a while. Add the Sierras and you have all the kinds of toplogy and differing rainfall.

How do you get a single number?

Apr 11, 2017
Rainfall is just the tip of the iceberg in terms of lack of information. If you look at 64 different event types that NOAA now tracks we have data on almost all of them for less than 40 years. People would write in newspapers about storms but nobody could track the extent or severity in the way we can today. It is well known that twisters are being recorded far more than before but nobody thinks they are occurring more. It's just that we can now track them. There are more people, more instruments, more satellites. We have to face the fact for most information about the past we have nothing. Until 2000 the ocean was essentially a complete black hole. The temperature readings were surface and spotty and inaccurate. We knew nothing about deep temperature flows or mantle interactions and we still don't. Even our ARGO floats cover less than 50% of the ocean volume and are lacking anything below 3-6 thousand feet depth. We know only the smallest pieces of information.

Apr 11, 2017
Okay,. . . so how do you get a single number?

Apr 11, 2017
Most of the records we have of the past are based on very few data points. Ice cores dug in 31 places of the Antarctic or arctic regions. How does 30 ice cores give us a complete accurate history and all those ice cores show is a snapshot of the atmosphere possibly. Relating that to every chemical and proxy of data is impossible.

We have rainfall records for 150 years. A 100 year storm is a 100 year storm. It is not THAT rare. We don't even know what is a 100 years storm becauase we don't really have accurate data on storms for more than 30-40 years for most of the earth. How can we compute the probability of a 100 year storm when we don't have 100 years of data let alone 400 or 500 that might be more reasonable for such an estimate. This is typical of the climate alarmist crowd. Trying to turn everything that happened yesterday into the be all and end all of extremism as if we are the most special people to have ever lived in the world. It's stupid.

Apr 11, 2017
We have to disagree. There is no doubt we are in for something extreme.

Apr 11, 2017
Nope. He was unable to answer the simple question of how he got a single number.

It was all obfuscation.

Apr 11, 2017
Please read his first post.

California has the Sierras, soggy redwoods, a thousand mile Central Valley and dry deserts. Where did that single number for each year come from?

Where was the rain gauge?

Apr 11, 2017

It cannot represent the entire state. We have many microclimates just here in the Bay Area.

Those of you who live elsewhere may not understand the differences.

Apr 11, 2017
Anyone who starts out with the phrase "This article is fake news" has just advertised the fact that they have a delusion to validate. The next sentence is a real doozy - "I have records for every month of rainfall in california going back to 1850". Next he will tell you that he personally compiled those records.
All these are significant indications that the poster has a level of psychosis sufficient to eliminate any associated input from serious consideration by any sane participant, especially when followed by further postings that read like a Charlie Manson interview - they start out dodgy and head straight to sheer lunacy.

Apr 11, 2017
This article is fake news. I have records for every month of rainfall in california going back to 1850. The lowest 4 year period in state history is not 2012-2015. The period 1986–1989 had exactly the same 4 year low as this which was 63 inches.

Knock it off. The Politically Correct crowd living here, does not care on ewhit about Real Science or the accuracy of your facts, just ask George gkam,

Apr 11, 2017

The proper term is "Scientifically Correct".

Apr 11, 2017
This article is fake news. I have records for every month of rainfall in california going back to 1850
what is your record source?

the source for the study (not article) is:
NOAA's National Centers for Environmental Information
so, the first thing i will ask for is a link to your references

the basic reason is direct from the study
unprecedented in the instrumental record.
by definition that means the official collected data presented and filed by agencies
moreover, it specifically states
This article employs spatially-explicit precipitation reconstructions for California in combination with instrumental data to provide perspective on this event since 1571
well, going back to 1571 definitely uses a larger data set than your going back to 1850

so to present a logical refute to the above, you would first have to present your source
then you would have to present evidence that this isn't considered in the study

Apr 11, 2017
I'm also curious about the data john_mathon has. Do you have a link? Is it for one station or is it an aggregate of stations all over California?

Just for fun I looked at a station in Los Angeles where drought is worse than most areas.


It shows the 4-year period ending in 2015 as the lowest in the 140 year record with the period ending in 2016 as the next lowest, followed by 1951, 1990, 1901, 1962, 1950.... There's no real pattern here except that the last 2 years were record lows in the 140 year record. Record lows aren't trends though.

There appears to be no trend whatsoever, which is consistent with what the IPCC found. There is no measured pattern of increasing drought globally despite their confident computer predictions that global warming will increase drought. They also predict it will increase precipitation, so go figure. (IPCC AR5, Chapter 10, p. 871)

Apr 11, 2017
an excellent citation...
Did you check his numbers?
exactly how can anyone check the numbers when there is no source to check?
just a vague reference to NCAR- nothing specific at all

it's not like there is a linked page or reference above that points to anything... and published data going back to 1850 means you need source material

can you provide evidence from the study that this data is being ignored?

can you show where this data is not included in the study?

making a claim isn't equivalent to proving a point

it is also not a logical presentation or "excellent citation as to why" one should believe the opinion of the poster

to refute the science one must present equivalent evidence
there is no reference available above from John to validate - only a claim
at best, this is an untested claim: http://www.auburn...ion.html

Apr 11, 2017
Sorry, the link for LA rain, 1877-2016 is:


There are still 3 months to count. The year-to-date total is:


Apr 12, 2017
"This news is fake" .... pretty inflammatory.

But here is a small datapoint: NOAA reported that the past March in Central Texas was the hottest on record (going back to 1880). (We're all gonna fry!) Yet my utility bill showed that during the period, the average temp was two degrees cooler than the previous year's corresponding period. Don't know where exactly the utiliity's thermometer is sited, but it's in Central Texas. Shouldn't it show the same "record" heat?

Statistics can be fun AND profitable!

Please explain how this can be.

Apr 12, 2017
" the average temp was two degrees cooler "

Yes, . . peak versus average.

Time for school.

Apr 12, 2017
But here is a small datapoint: NOAA reported that the past March in Central Texas was the hottest on record (going back to 1880). (We're all gonna fry!) Yet my utility bill showed that during the period, the average temp was two degrees cooler than the previous year's corresponding period
location of measurement

terrain around gauges

time of measurement - Depending on the time interval between 2 readings, the values may not represent the actual maximum or minimum temperature

consistency and accuracy - more than likely your gauges are not certified for accuracy and checked/maintained regularly and they may not be placed in proper locations per the NOAA mandate

the temperature half way up a mountain (especially of considerable size and mass) will always be different than the top/bottom

Apr 12, 2017
To refute "data" one must present conflictionary "data" are confused about science vs. data
no, i am not - John and you are

the reason: to refute the scientifically measured and certified data there must be equivalent data
That said, if John could return and present HIS source data we could stop debating about whether the "scientific" conclusions drawn from the data are accurate...
yes and no

we cant learn and determine that the source is or is not accurate or equivalent for comparison (the yes part)

(the no part) you can't compare 6 apples to 6 firetrucks because they're both red and be accurate about anything except the colour

Apr 12, 2017
"Going back for English comprehension classes are you? Where is the "peak"?

The peak is what you argued: The highest temperature.

The "average" is usually intended to signify the arithmetic mean.

My gosh, . . .

Apr 12, 2017
John_mathon has gotten himself confused and thinks that it's ok to average all the temperatures from weatherstations together to get a state-wide average, despite the fact that over the last 167 years the number of weatherstations has increased and some locations have changed. Think about it this way: say there was a global network of weatherstations for a number of years and then a new station is installed in Antarctica. If we just blindly start averaging in that weather station and we see that the average has suddenly dropped, is it true that the globe's temperature has dropped or have we forgotten to account for the sudden addition of a data series from a location that is colder than average? The latter, of course. So we would have to deal with this additional data in one of two ways: ignore it entirely, or use data from nearby stations to interpolate the missing data from the previous years. John has done neither.

Apr 12, 2017
NOAA reported that the past March in Central Texas was the hottest on record

Can you point to the NOAA website where this claim is made? I can't find anything about this in NOAA's State of the Climate page for March (https://www.ncdc....l/201703 ). They do point out that it was the warmest winter for Texas, but nothing about Central Texas. Central Texas was 6F-9F warmer than average, so it's possible. I did find an article about Austin having the warmest March on record, but that's just a tiny part of Central Texas. Given that your utility's thermometer is an even tinier part, it's probably not a meaningful measure.

Statistics can be fun AND profitable!

I think you have to understand statistics first. ;)

Apr 13, 2017
Well his post clearly says "overall average" at least once and uses the word "average" 2 more times....the rain gauge is "all" of them operating in the state of California at the times of the measurements and the number is the average per either 4 year period or 1 year period which he specifies depending on the time frame of said measurements
NoNo you dont understand... george LIVES there.


It cannot represent the entire state. We have many microclimates just here in the Bay Area.

Those of you who live elsewhere may not understand the differences
-See? So of course hes going to know more than an actual scientist who lives there.

Because, you know, hes a psychopath and all.

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