Guest posts by Willis Eschenbach
Due to the lack of blood to my head, I posted my first comment on an article on PhysOrg titled “On this flooded island of the homeless, climate change has never been more real“. Trying their best to move our hearts, the article talks about some homeless people in Sacramento, California, who seem to believe the recent drought will last forever. The story was also chosen by LA Times and other documents. Of course, the LA Times can’t call them “homeless,” which is politically incorrect today. The term currently used by the heralds of noble virtue is “unhoused”…
[Lest you think I am without compassion for the homeless, please read my posts “Fixing The Brakes“, “Fixing The EGR“, and “Wandering In Wonderland“. But I digress …]
In any case, this is the plot. Thinking the river would never rise again, or perhaps not caring about it at all, a number of “homeless people” took up residence on a land jutting out into the Sacramento River called ” Bannon Island”. And of course, 100% predictably, after the last few years of little rain, recent heavy rains have slowly transformed the vacant lot. First, it turned back into an island, then into a partially submerged swamp. As the photo above shows, now these homeless people have to move to/from their place of residence by raft. Shocking, I know, and clearly a telltale sign of “climate change” to the uninformed about climate.
My comment is:
When California has been dry for the past few years, that drought has been attributed to “climate change,” and the people on Bannon Island are tall and dry. Mostly high.
Now we have rain again, Bannon Island is partially flooded and Bannon Island people are wet, but the possibility is still high… and that is also due to “climate change”…
You guys are a joke. If both wet and dry conditions can be blamed on climate change, EVERYTHING is a result of climate change. And that’s just pointless.
Get a handful. California has had both floods and droughts for millennia. And if you live on a lowland riverbed, you shouldn’t be surprised if rain can flood your home.
Of course.
w.
It may be a bit harsh in retrospect, but I don’t care for those who turn human stupidity and lack of foresight into some sort of bogus climate morality tale.
Amidst the usual mud-throwing personal attacks that are typical reactions of people with no scientific background, someone said:
This is quite clear even to high school students: more energy in a high-contrast system and mixed processes leads to increased extremes on both sides. You don’t even need earth science for this, which can greatly influence the outcome, exacerbating or diminishing events.
I’ve answered:
While this may be true in theory, in practice there has been LESS annual variation in precipitation in Sacramento recently. Variations in the 1800s were larger than they are today. See here for actual data. (Note that data is missing for the last few years.)
Unfortunately, the PhysOrg website does not allow images in comments. If they had, I would have posted this image.
Figure 1. Monthly rainfall, Sacramento, CA. The source: KNMI
Of course, this did not convince the man, who again resorted to a personal attack, saying that “It’s true in practice and you’re not a climate scientist.” I had to laugh at that, as my work has been cited by the IPCC as well as in a congressional submission to the EPA, and Google Scholar lists ~200 citations for various scientific papers by I.
However, it did give me an idea of how I might measure “climate extremes”. I decided to look at the standard deviation of the precipitation data for Sacramento. “Standard Deviation” is a measure of how spread the data is. If we currently have more extremes, i.e. more wet years and more drier years, then the standard deviation of recent data will be larger than the standard deviation of previous years.
“Standard deviation” measures the standard deviation of a number of years prior to a given year. I used the 30-year standard deviation in the figure below, meaning that each data point over time represents the standard deviation of the 30-year period prior to that point. Why 30 years? Well, calculations for that time period are often said to represent climate rather than weather. This is the result.
Figure 2. 30-year standard deviation of monthly precipitation in Sacramento, California. The photo shows one of the homeless residents on Bannon Island examining the unusual and erratic changes in the weather.
“Great,” I, “the deal is done!” … however, as happened more than once, in the night I woke up and thought “Wait, I forgot something!” Grrr… what I missed was the fact that when mean rainfall decreases, as happened in Sacramento, we expect the standard deviation to decrease as well. So Figure 1 doesn’t show what I want to investigate.
Of course, that kept me tossing and turning for the rest of the night, until I woke up early and did my calculations again by expressing them as the 30-year standard deviation divided by the value average (average) spanning 30 years of values. This removes the effects of changes in the mean over time. Here is that result.
Figure 3. 30-year standard deviation of monthly precipitation divided by the 30-year mean (mean) of monthly precipitation, Sacramento, California.
So that is recommended. The shape of the curve has changed, but the conclusion about the descending extremes has not changed.
When I saw that I had a different thought, viz, Well, maybe I’m missing the short-term rise at the extremes masked by looking at a 30-year period.. So instead, I looked at the standard deviation after 6 years divided by the mean after 6 years as shown below.
Figure 4. 6-year standard deviation of monthly precipitation divided by 6-year mean of monthly precipitation, Sacramento, California.
Obviously, although the overall temperature increases and “more energy in the system”the change in precipitation in Sacramento is becoming less severe, not so severe… just imagine.
Someday in the future I might look at some other datasets… any suggestions on what data it might reveal are happily accepted, but there are no guarantees. Ars longa, vita brevis …
Rain in California is very important to me because I live in a redwood forest about six miles inland from the Pacific Ocean, an hour and a half north of San Francisco… and the rain continues to fall. Supposed to rain every day for the next ten days, looks like a real frog strangler. However, I have no complaints, it fills the groundwater table so our well will produce water next summer.
My best wishes to all, wet or dry, stay or not,
w.
As is my custom: I ask that when you comment, you quote exactly the words you are discussing. This lets people know exactly who and what you’re discussing, and avoids many of the misunderstandings that plague the Web.
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