Another debunking of the Southwest Megadrought Panic and attribution to Climate Change.
from the Cliff Mass Weather Blog
Dr. Clifford Mass
During the past week, many major media websites have headlined a study by some UCLA researchers suggesting that the Southwest U.S. is in a megadrought–the worst in 1200 years– and that global warming is the prime cause.
To illustrate, below is the front page of the LA Times. And the Seattle Times highlighted the megadrought claims as well.
Unfortunately, there are some major problems with this study and many of the hyperbolic claims–as I will explain below.
The US Southwest has clearly experienced a dry spell recently, but global warming (a.k.a. climate change) is only a minor contributor compared to natural variability. Decadal dry periods are not unusual or unknown for the U.S. Southwest. They have happened many times before during periods when human-caused climate change could not be the origin.
Why 22 years?
A key aspect of this paper is its claim that the last 22 years were the driest over the southwest U.S. for the past 1200 years. Their measure of dryness was soil moisture and they secured this indirectly by relating tree ring chronologies to such moisture. Here is a plot of soil moisture from their paper:
Figure 1b from Williams et al. 2002. Nature Climate Change. The soil moisture is expressed as standard deviations from the mean.
Tree rings are, of course, imperfect measurements of soil moisture, but let’s put that aside for the moment.
You will notice a lot of ups and down in southwest U.S. soil moisture, and that in most ways, the recent dry period is unremarkable. In fact, there were many previous events in which the soil moisture was drier. There were many periods when the soil moisture was low (say less than -1) for longer periods.
Now, I am not a little surprised that none of the “curious” media stopped for a moment and asked: why did these researchers pick 22 years? Why not 25 years, 30 years, or 50 years?The answer is that their whole narrative, their whole claim of unusual drought, would have weakened greatly if they had used 25 years or 30 years or anything longer.
You can see the issue from the plot above. The soil moisture was in fact VERY HIGH during the 1990s, including 1998. If they had used a longer period, they would have found more normal conditions.
If you want to see this more clearly, let me show you the Palmer Drought Index over California during the past 120 years (see below). This index combines temperature and precipitation and is a reasonable thing to compare to their soil moisture index.
The 22 year period (red, -1.51)) has an average that is much lower than the past 30 years (blue -.93) or the past 25 years (cyan, -1.24). This effect is even larger if you look at precipitation. By selecting 22 years they avoided the wet period in the mid to late 1990s.
Now I am not comfortable with their approach, with claims of megadrought dependent on selecting the exact period over which it recently has been dry.
What is the origin of the two-decade dry period?
There is little doubt that it has been relatively (but not record) dry over the southwest U.S. during the past two decades. The authors of this paper claim it is mainly due to global warming, but there is strong evidence that this is not the case.
Something unusual has been going on during the past 20 years: persistent ridging (high pressure) during the winter over the northeastern Pacific. And such high pressure has kept storms away from the southwest U.S.
Several highly regarded atmospheric scientists have investigated this issue and have found that the persistent high pressure and associated warm sea surface temperatures off the West Coast are due to natural variability, not global warming. This work has been published in the peer-reviewed literature (see one below).
Specifically, natural variability, like changes in the Pacific Decadal Oscillation, is what forced the unusually warm, dry conditions of the past 20 years, and there is no evidence that global warming is contributing.
The authors of the megadrought paper, for some reason, ignored the obvious role of natural variability but focused on output from global climate models (GCMs). Such climate models, forced by increasing greenhouse gases, simulated substantial warming during the past 20 years, drying the soils and thus leading to the author’s claims that the 22-year megadrought was mainly the result of greenhouse gas emissions.
But there are substantial problems with such models and their application to this problem.
Climate models are known for their failure to properly simulate (or simulate at all) key modes of natural variability like the Pacific Decadal Oscillation. The particular models used in this work (CMIP-6) are well known to be overly sensitive to greenhouse gas concentrations. There are substantial problems with global climate model physics, such as their unphysical cloud coverage (something I am researching) and poor simulation of convection (thunderstorms). And there are many other known deficiencies. In addition, these models have been tuned to match the climate of the past century, which may undermine their ability to predict the future reliably.
In short, just because the climate models were producing warming over the southwest U.S. does not mean that increasing greenhouse gases were actually the cause, particularly when there is very good published science that suggests otherwise. Furthermore, the climate models have well-known major deficiencies.
The southwest U.S. has always experienced periodic droughts that have extended over decades and the fact that this has occurred for thousands of years shows that global warming from increasing greenhouse gases is not the cause. This is part of the meteorology/climatology of the region.
We are in the midst of a dry period that is not particularly unusual in intensity and there is strong evidence that it is the result of natural variability.
The best science we have now suggests that increasing greenhouse gases will have uncertain effects on southwest U.S. precipitation during this century. Regarding temperatures, at this point in time, global warming effects are probably small compared to natural variability but will increase during this century as greenhouse gas emissions increase and the atmosphere and ocean slowly warm.
I like the dispassionate language.
Cliff you had me until “increase during this century as greenhouse gas emissions increase”. Chances are the CO2 will decrease as we exit the current Interglacial which is overdue and the cooling of the oceans due diminished solar inactivity and CO2 absorbtiity by the oceans.
The timing is most important for flawed studies to improve their standing. In this case it is short term La Nina conditions.
No. It is part of the GB cycle.
Southern California = (Starting year 2000 !) LA Nina, LA Nina, Average (No anything), LA Nina, Average, Average, LA Nina, LA Nina, LA Nina, Average………….
[ EL NINO ] is DEAD, dead and buried, a joke, non-existent, yester-years (Pre 2000), no more to be recognized!!!!!!!
Warming Pacific ???????
WHERE IS THAT ?
NOT SOUTHERN CALIFORNIA WATERS !
And don’t believe that BS 2015/2016 El Nino Crap, that was an underwater (Below-the-Surface) Volcano, about 2000 miles West of Seattle, in the very Southern Alaskan waters that caused a very warm pool of ocean water/sea Temps that made its way up to the Gulf of Alaska causing some of the warmest temperatures on record (Alaska, British Columbia, Seattle, Portland…).
So Warming ?
Somewhere else, over land, possibly, but not the Easter Pacific Ocean/West Coast of the United States !!!
La Nina’s SUCK, and the High Pressure Systems they produce SUCK even more !!!!!!!!!!!!
Besides Santa Ana winds, WEATHER-IS-DEAD-IN-SOUTHERN-CALIFORNIA… !
Long live the Warm 70’s, 80’s and 90’s and the Winter Storms and Rains they brought !
Enough explanation points here ?
Next year’s rains should fix the drought….my prediction…..and I’m right about half the time….
“I’m right about half the time…”
That’s what the IPCC calls “medium confidence”..
Not exactly. The phrase “about as likely as not” is used for probabilities in the range 33-66%. The term “confidence” is used to describe the amount of evidence and the agreement of that evidence. For example the probability of a 14C atom surviving 5730 years is about as likely as not. But this is known with high confidence.
Badwaxjob, What you fail to understand is the difference between accuracy and precision. Think of an archer firing arrows at a target. If he clusters his arrows tightly but they all hit the target at the same place away from the bullseye, he’s precise but not accurate. If all his arrows hit the bullseye he’s both accurate and precise. If he sprays his arrows all over the target but their average location is near the bullseye, he might be accurate but he’s certainly not precise. It’s hard to say whether he’s accurate with any confidence as the next arrow could change the finding. You need a lot of arrows to have confidence in any statement about accuracy.
It’s the same with IPCC analyses of various climate measures (like drought or cyclone frequency) – if the data varies dramatically by map location or varies dramatically over time, like it usually does because of weather, it’s hard to make an accurate statement about the trend in the measure as the next bit of data could change the result. This is fundamentally unlike your (stupid) analogy as you could only make a precise and accurate prediction because the underlying physics behind radioactive decay is known. That’s NOT the case with weather – weather is chaotic.
So, to translate IPCC-speak, when they say they have a medium confidence in a particular result they’re really saying that they can’t make either a precise or an accurate prediction. They actually don’t know squat about most things, simply put.
This has nothing to do with accuracy or precision. Those terms are related to a completely different concept. See ISO 5725 for more information.
The old define your own term method .. Nick Stokes would approve.
This reminds of when they chose a higher confidence level to increase the spread of their confidence intervals for projections of global temperature anomalies, in order to just overlap with reality. This was then spun into climate scientists being 95% confident now instead of 90%.
Would it be fair to say “definitely might happen” would be high confidence?
No, half the time you’re right every time.
How many recognized Climate Scientists could document a 50% correct forecast rate?
All statistics are 50/50; something happens or it doesn’t.
Ironically, any 50/50 probability scenario, like a coin toss, almost never comes up exactly 50 out of a hundred one way or the other. In this same way, the daily average temperature for any give location very rarely matches the global average temperature.
Warmer air holds more moisture yet somehow leads to drought? Then again, AGW increases polar temperatures reducing the temperature gradient between the poles and the equator yet leads to more severe weather, so with AGW the opposite of what should be expected is “TRUTH”.
One group of warmists proclaim that warmer air holds more moisture, and this leads to drought.
Another group of warmists proclaim that warmer air holds more moisture, and this leads to floods.
Sometimes it does, sometimes it doesn’t! In other words, no correlation between humidity and precipitation.
Yes. warmer air CAN hold more moisture, but it still has to acquire that moisture somewhere. Once it has that moisture, it is somewhat bless inclined to give it up. Warm dry air will dry out the areas it comes to, while warm moist air may or may not precipitate when it comes to an area. The precipitation may be greater if the air cools sufficiently, or it may be the similar or even less. Just to complicate things, changes in altitude of an air mass will typically create significant changes in temperature which will determine the amount of precipitation. This weather stuff is hard! that’s why a legion of pseud-scientists pretty much just guesses in the most assured tones they can muster while hedging their predictions with might, may, possibly, probably, etc. weasel words.
If there had been 22 years of wet, then AGW would have been blamed for the same reasons.
“Their measure of dryness was soil moisture and they secured this indirectly by relating tree ring chronologies to such moisture.”
Tree rings are neither thermometers nor moisture detectors. They may give a vague hint about something but certainly not nearly enough to draw major conclusions.
Tree rings are a reliable indicator of how many annual cycles a tree has survived. I’d be willing to bet that I could sample several trees from my wood lot and not find any meaningful correlations in the width of the rings.
Forgetting rings, the latitude and altitude that particular trees appear or disappear from tells us something…except around the hills here where we have spruce, fir, hardwood, cedar, pine of various stripes and even yucca on some slopes…all in a big hodge podge of microcosms..seen fir that germinated about 20 yrs ago around a 1000 ft lower than the norm…seems to be growing fine…either they like warm weather or it’s getting colder (I tend to associate them with cold) and as of yet, not seen any palm trees migrating into the area…anyway, stumps exist well north of current tree line in the N hemisphere, probably placed there by clever creation theorists.
So much for dendrochronology.
Tree ring width is affected by LOTS of things. Insect infestations, fungal infestations, shade from other trees (trees in a forest setting have narrower rings because of shading than those in a pasture, for instance), nutrient sharing with other plants/trees (e.g. root entanglement). Moisture is just one factor among many.
The study is paywalled so I can’t tell if they used any confounding factors to weight their data values. If not then the study is worthless.
BTW, the Southwest, including central and south California, is classified as arid desert or semi-arid desert. Both are typically low moisture climates. What did they actually expect to find with this study?
I see the soil moisture chart- but not the original tree ring data- which I’d like to see. No doubt in an arid area there is a vague relationship between soil mositure and tree ring growth but not nearly enough to draw strong conclusions. All of the things you mentioned and many others will effect the growth of the rings. If one ring is 10% wider than the previous ring- what exactly is the conclusion? Can they conclude that there was 10% more rain? Maybe there was the same amount of rain but the temperature was not so hot- which might allow the tree to grow more that year. Attempting to correlate tree ring width with the climate is a fantasy. But, in the news item, it says that the researchers claim 42% of the drought’s severity is due to increased greenhouse gases causing climate change? How the hell can they draw that conclusion? Not 41%- not 43%- but 42%! The reporter, Ian James, isn’t smart enough to challenge this “research”?? Apparently not. I wonder how many trees were studied? I should think it should be thousands but I bet it was very few.
I believe that it can also depend on just where a bear decides to relieve itself in the woods.
Moisture, like warmth does not impact plant growth in a linear fashion. Both too little and too much moisture will impeded plant growth.
On flat ground, flooding might lead to disease. Many days of light rain will mean less water soaking in. On a slope, regular rain fall would be better than a large dump, that would wash away nutrients. How beneficial the rain was would be seasonally dependent where there are shallow roots or good drainage. Trees watered by snow melt (possibly the rafters used in the study) would be worse off by heavy spring rain that washes the snow away.
It’s not that the proxies can’t show a similar trend to what is measured. It’s that you can’t compare magnitudes with modern measurements, let alone come up with 41% was due to climate change when 100% of the 8% difference could be due to comparing measurements with proxies.
They can’t even tell if a tree was shaded during a portion of its life. Tree rings are garbage unless sampled very widely and correlated with better known events. MIchael Mann’s work was meant to achieve a predetermined result. It wasn’t science at all and many of his peers use the same deliberately flawed methodologies.
Just one of the tricks Michael Mann and crew used was to calibrate Bristlecone Pine ring-widths with Northern Hemisphere (North American?) average temperatures, not Southwest American local temperatures. S. Clemens: Figures don’t lie by liars can figure.
Another fly in the ointment: tree ring width always diminishes as the tree gets older. The ring is a cross-section of a sheath of annual new wood coating the outside of the tree (under the bark). As the tree diameter increases, the surface area of the sheath must increase. If total growth was constant year to year, the width of the sheath must (and does) diminish.
Of course, growth is not constant but instead is sigmoid or “S-shaped” (cumulative growth) and parabolic (growth rate). Peak diameter incremental growth occurs when a tree is 20-30 years old. Thereafter the diameter growth rate declines, and so do ring widths. There is no reason tree ring width should be constant on any tree, and every reason that ring widths must diminish with age.
Thanks! I hadn’t considered tree diameter. Without that knowledge there is no way to calibrate indications from a bore into the tree. Root growth also can’t increase indefinitely. Thus the nutrient flow into the tree per unit volume of the tree will also go down. This would also affect ring width.
It just gets more and more apparent every year that far too many environmentalists and climate scientists have no physical experience in the field – all their experience is in a lab or computer using models or simulations.
I wonder if any of these so-called climate scientists consulted a forester, a logger, or even a game warden with years of experience as a peer-reviewer or as a consultant on designing their study?
Under guidance of a forester here we look at rings of the bigger trees that we gather for firewood (using a lot of that this winter). The rings not only tell us the age of the tree but you can see when dry spells hit (late 1800’s & circa 1940). Later years have been wetter and the trees grew at impressive rate, perhaps aided by abundant CO2 or not. The biggest trees being gathered were well toward the end expected life spans when they fell.
And with 10x or so more trees per acre as there should be, is it any wonder soil moisture is depleted?
natural fire used to do that but then came smokey the bear
Aside from the failings of warmunists’ models to correctly model the world, a couple of points here need to be made to put things in proper perspective:
1) The southwestern quadrant of the US is and always has been dry, therefore in a state of “drought” as compared to any other sections of the US. Precipitation values and trends only deal with how dry the normally dry conditions are.
2) Most of the precipitation that matters – as far as maintaining existing ecosystems, and providing human requirements for domestic water and for irrigation of crops – for the entire southwest is contained and stored annually in the high mountains, the majority of which are comprised of the southern Rocky Mountains in Colorado, with some contribution from the Sierra Nevada, though that contribution is very small compared with the Rockies.
Now, look at the current snowpack water content map produced by NRCS at https://www.nrcs.usda.gov/wps/portal/nrcs/main/co/snow/products/. From this map it appears that nearly half of Colorado, and most of its high mountain areas with significant snowpack (not the deserts of western Colorado) are experiencing average snowpack (90-109%) compared to the statistical average snowpack experienced in 1991-2020. It is these high mountain snowpacks that supply most of the irrigation and drinking water volume for the entire southwestern US.
It is not a “mega drought” … nor even much of a drought at all.
I can attest to the dry spell in Colorado being over at least temporarily. Snowfall was sparse until about the Marshall fire and above average afterward.
It’s actually unusual to have snow on the ground in the Denver area for long periods, but that has been the case for the past several weeks and more snow is coming in after a warmup this weekend.
A graph shows the 93%. The dark black line shows we’re just below the 30-year mean snow-water content of our snowpack in Colorado.
There’s plenty of water in the snowpack, and not just for the front range. As Duane’s graph makes clear, a near-average amount of water is in the works for all the western slope drainages: The White River, Yampa, Colorado, Las Animas, Dolores, Rio Grande, Gunnison and the San Juan Rivers.
We do this every year.
How many times can they cry wolf before their cries are drowned out by reality?
Every year parts of the Southwest will suffer water shortages, and the West, continues to grow. Colorado’s population grew 15% over the last 20 years. If we continue to get average snowpacks, and nature’s supply ramains constant, then that supply must be allotted differently. This (in my mind unfortunate) adaptation is because of demographics, not climate change.
Correction: Colorado’s population grew 15% over the last ten years, not 20.
I can not believe the accuracy of that graph, soil moisture going back that far? NO way.
What temps, precip, and centuries made the southwest a desert to begin with? Any thing unique recently that makes it more of a desert? Climate designations don’t change in the short time frame of this study. You would think any (so-called) scientist would first ask themselves what is the climate we are examining!
Let’s assume for the sake of argument that most – say 80% – of the land area of the southwest averages only 10 inches of precipitation per year, nearly all of which either immediately evaporates or infiltrates into the water table, and is therefore not available to support vegetation or human water demands. But the other 20% gets 50 inches of annual precipitation, most of which is in the form of snowpack that gets released during the spring melt, nearly all of which is in the form of runoff which in turn is stored in controllable reservoirs.
This is a pretty accurate model of the southwestern US.
So let’s also say that the desert areas are in drought, and only get 8 inches of precipitation instead of 10 inches, of which virtually 0% runs off. The practical effect of this declared “drought” is negligible … especially when the high mountains receives near average precip, most of which runs off and is stored for practical uses, such as irrigation and domestic water demands. For city dwellers and farmers, the “drought” in the lowlands is a non-factor.
I guess I was approaching it from a different standpoint. The area has been a desert probably for millennia. It has little rainfall, and as you say, it disappears from the biosphere very quickly. My point is that it is erroneous to proclaim rising CO2 makes it “more” of a desert than it has been for a very long time.
And your evidence for that statement is….
More tumbleweeds, no doubt.
I love the way griff goes out of his way to present arguments showing why the article is wrong and why we should all believe as he does.
Do you have any “supporting evidence” — e.g. references or links or detailed logical arguments, as used in the ATL article — for your bald assertion ?
It takes no logic to conform to an idée fixe. It requires only dogmatism.
Given your belief that the UK is 3% wetter … you probably need to explain how increase water leads to droughts. Increased rainfall leading to increased drought is a NO so your YES stands as a beacon of your stupidity..
“…focused on output from global climate models…”
They have to do this because models is all they’ve got.
What is the resolution for the proxies?
Is this another case of comparing yearly or monthly data against data that has been smoothed to decades if not centuries?
I megadoubt it.
Another issue is that much of the rain that does fall in the American southwest, falls during the yearly monsoon season. Once soils reach saturation, any extra moisture is going to run off into the rivers and end up in the oceans.
Is this the drought that caused problems at the Oroville dam?
Oroville Dam crisis 5 years after 180,000 people were sent fleeing (mercurynews.com)
Let’s hope the “megadrought” doesn’t come to an end.
Thanks, Cliff, for the realistic analysis.
And thanks, WUWT, for cross posting it here.
How much of the western drought is due to directing surface water into domestic water systems never to hydrate the soil?
can’t talk about that…the believers all live in cities that suck up all the water…and the believers are free of sin.
“….all live in cities that suck up all the water”
Not per capita. FYI, the link includes the indirect water usage you might be tempted to wudaboud aboud…
Julander and Clayton using decadal snowpack data showed that the current condition in Utah was similar to previous dry decades over the period of 1930 to about 2015. using only the best, serially complete snow course data that were unimpacted by other variables such as vegetation change and encroachment – snowpacks have declined about 3 to 6%… adding the past few years would make those figures even higher – maybe as high as 10 or 15% but still similar and statistically not different that previous decades. Robert gillies, climatologist at Utah state published a very similar paper at the same time indicating that snowpacks in utha had declined 9%.
This is a regional episodic climate change cycle which has been dated back thousands of years, and might go back to the end of the last ice age. Global warming has nothing to do with it, but it really is a climate change cycle. It’s just confined to the American Southwest.
Basically the 20th century was the wettest century in the past 2000 years for the American Southwest. OTOH, the average precipitation for the Southwest is 2/3 of what we had during the 20th century. A real Southwest regional drought has only 1/3 of the 20th century’s precipitation, and real droughts here can go on for hundreds of years. Those are called megadroughts.
Paleoclimatologists have said for about 10-15 years now that it looks like a megadrought is starting in the Southwest, and some now say this is definitely the start of such a megadrought.
Here is one book about this: _The West without Water: What Past Floods, Droughts, and Other Climatic Clues Tell Us about Tomorrow_ , by B. Lynn Ingram and Frances Malamud-Roam
Its Amazon link is:
Ummmm…. I want to be sure I understand this: there is a drought in the US desert areas, essentially in places that have a long, long history of drought and at best, low precipitation levels…. and this is something ODD?
Someone please be kind enough to explain to me what planet these newspaper/media/grant-seeking people come from, because I only have so much popcorn to survive on if I have to face much more of this.
The North American continent’s southwest portion goes through repeated cycles of prolonged rainy & cold weather with flooding, and prolonged cycles of heat and drought during which plants that survive are extremely hardy, e.g., cactus of all sorts. There is nothing unusual about this, but it attracts the grants-seekers like spilled sugar attracts ants to a picnic table.
Here’s why they fail as observers: The winter squall projected by the NWS arrived, but the bulk of the snow was to the south of me, all the way down to the center of the state. IF we got an inch of white fluffy stuff up here in my AO, the Sun has reduced it to rivulets,m whereas south of Chicago the snow depth goes as high as 12 inches. That is WINTER SNOW patterns, people, and has everything to do with moisture levels and which way the wind blows. We had less that I hoped for because it goes into the local groundwater systems, but that’s how it is. Further south, truckers were stuck in drifts up to their cab doors.
That is W-E-A-T-H-E-R. Same as the things that hapen at Lake Mead and other areas, and nothing about the weather can be controlled. When I was in grade school a million years ago, we had heavy snows every winter. Ice storms were common and highways had to be plowed out and cinders (from coal-fired trains, no salt usage then) were spread to make the roads safer to drive on.
I think it’s worse in Norway and Sweden, but I’ve never been there and they like winter sports, anyway.
I live in Western Canada. Like the U.S. SouthWest, our moisture fights its way to us over the Rocky mountains and arrives much diminished. Almost all of this moisture originates as evaporation from the Pacific Ocean. Like the U.S. SouthWest, we have periodic drought and we can practice agriculture here only because a significant amount of moisture arrives as snow in winter and doesn’t melt until spring, making it available at the time of germination.
While the SouthWest may be experiencing a dry spell, Western Canada has not seen a wetter 20 year period in my 64 years than we have had since 2000.
I would be very surprised if this does not correlate to SouthWest moisture levels, as all this moisture has to come from the Pacific. I expect that our weather patterns deliver moisture somewhere on a North-South band that is variable and cannot come to both places equally or consistently. Sometimes we get it and sometimes you get it. We are not as drought prone because we don’t dry out during the winter. That’s it.
A cold surface to the north heralds a high over northwestern Canada.
Was Human activity a significant driver 1200 years ago? If not, what was? And how does one know that Human activity is a significant driver today and not whatever the driver was in the past?
Why the forced global warming is (also) involved in these droughts: https://kaltesonne-de.translate.goog/warum-feuer-im-sueden-der-usa-ein-echtes-klimawandelsignal-darstellen/?_x_tr_sl=de&_x_tr_tl=en&_x_tr_hl=de&_x_tr_pto=wapp
I agree there’s a problem with picking 22 years. Saying that the GMST has not gone up in the past 6 years or whatever is has a similar problem. Why that start date? One can argue that’s different because… Picking starting and ending dates is not science. Perhaps comparisons can be made comparing all dates and averaging them. In this case use 12 through 32 years. But that’s not science either. I am sure Willis could whip up a plot showing those 21 different time frames. That 22 years is the cardinal rules tip off on an emergency is B.S. That the beginning of a warming pause is this one specific date is also B.S. It may be an effective tactic though.
What I find remarkable is that in the other hemisphere we’ve also going through a horrible drought over the last 15 years or so. Perú and especially Chile are suffering a lot bc of it (we’re a few months behind having to ration water in Santiago…pretty bad). Of course we have a mediterranean weather prone to drought, but still, it’s become quite dire. The interesting thing is that the drought here is also caused by cold seas and high pressure systems blocking the rains. I wonder if simultaneous droughts in the Pacific coasts – both north and south – are a recurrent event
The weakening of the solar wind magnetic field during the 24th and 25th solar cycles favors blocking the jet current. It causes a weaker flow of air from the ocean over the continent. In addition, La Niña, which lengthens at low solar activity, is now in effect.