Climate change could mean fewer sunny days for hot regions banking on solar power


Research News


While solar power is a leading form of renewable energy, new research suggests that changes to regional climates brought on by global warming could make areas currently considered ideal for solar power production less viable in the future.

Princeton-based researchers recently published in the journal Nature Communications the first study to assess the day-to-day reliability of solar energy under climate change. The team used satellite data and climate models to project how sunlight reaching the ground would be affected as warmer global temperatures alter the dynamics and consistency of Earth’s atmosphere.

Their study found that higher surface temperatures — and the resulting increase in the amount of moisture, aerosols and particulates in the atmosphere — may result in an overall decrease in solar radiation and an uptick in the number of cloudy days. Hot, arid regions such as the Middle East and the American Southwest — considered among the highest potential producers of solar energy — were most susceptible to greater fluctuations in sunlight, the researchers found.

“Our results could help in designing better solar power plants and optimizing storage while also avoiding the expansion of solar power capacity in areas where sunlight intermittency under future climate conditions may be too high to make solar reliable,” said corresponding author Amilcare Porporato, Princeton’s Thomas J. Wu ’94 Professor of Civil and Environmental Engineering and the Princeton Environmental Institute (PEI). The research was supported by the Carbon Mitigation Initiative based in PEI.

“To use an academic metaphor, in terms of solar power, semiarid places are now like students who get an A nearly every day,” Porporato said. “Now, climate change is disturbing the usual dynamics of the atmosphere and the regularity of the solar radiation reaching the planet’s surface. We tried to quantify how much more often those A’s could become B’s, or even C’s, as a result.”

Existing research on how solar energy will fare in this irregular future has largely focused on average levels of sunlight, said first author Jun Yin, a researcher at Nanjing University of Information Science and Technology who worked on the paper at Princeton as a postdoctoral research associate with Porporato.

“The novelty of our approach was to point out that in some places there is going to be more uncertainty in day-to-day variability,” Yin said. He and Porporato previously reported that climate models underestimate the cooling effect of the daily cloud cycle. They worked on the most recent paper with co-author Annalisa Molini, an associate professor of civil infrastructure and environmental engineering at Khalifa University in the United Arab Emirates.

The researchers’ findings were based on probabilistic calculations similar to those used to determine the risk of flooding or drought. The reduced reliability of solar energy is related to the increased variability of atmospheric moisture and aerosols in some arid regions. Higher temperatures hold more moisture and are more turbulent, which favors the formation of clouds and keeps particles in suspension longer, Porporato said.

“Then there is the issue of soils drying, which may be even more important,” Porporato said. As temperatures and atmospheric turbulence increase in arid regions such as the Middle East, dry soils potentially lead to greater amounts of dust and atmospheric aerosols that would diminish solar radiation. These trends are in fact already detectable in observations from climate-observation networks, Porporato said.

For the American Southwest, the researchers’ findings were less consistent. Some models showed more solar radiation and lower intermittency in the future, while others showed less solar radiation and higher intermittency. These results illustrate the challenge of trying to predict the reliability of solar energy in an uncertain future, Yin said.

“We hope that policymakers and people in the energy industry can take advantage of this information to more efficiently design and manage photovoltaic facilities,” Yin said.

“Our paper helps identify efficient solutions for different locations where intermittency could occur, but at an acceptable level,” he said. “A variety of technologies such as power storage, or power-operation policies such as smart curtailment, load shaping or geographical dispersion, are promising solutions.”

To follow up on their work, the researchers plan to examine climate persistency — specifically, the number of consecutive sunny or cloudy days — which is important for solar power. They also are exploring how clouds could affect the effectiveness of tree planting as a climate mitigation strategy. Trees absorb not only carbon dioxide but also solar energy, which would raise surface temperatures. A resulting increase in cloud coverage could change current estimates of how effective trees would be in reducing atmospheric carbon.


The paper, “Impacts of solar intermittency on future photovoltaic reliability,” was published Sept. 22 by Nature Communications. The work was supported by the USDA Agricultural Research Service (grant no. 58-6408-3-027); the National Science Foundation (grant nos. EAR-1331846, EAR-1316258 and FESD EAR-1338694); the PEI Carbon Mitigation Initiative; the National Natural Science Foundation of China (grant nos. 41877158 and 51739009); Nanjing University of Information Science and Technology (grant no. 1441052001003); the Jiangsu distinguished faculty program; and the Khalifa University Competitive Internal Research Award (grant no. CIRA-2018-102).

From EurekAlert!

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Walter J Horsting
October 8, 2020 6:19 am

Uh…lower solar wind allows more cosmic ray forming clouds….I predict more clouds in the future from current Grand Solar Minimum.

Reply to  Walter J Horsting
October 8, 2020 8:06 am

Hi Walter,
We are not there yet, just 3/4 of the way to the Dalton Minimum of the early 1800
Napoleon to Russia and all such things 🙂
comment image

October 8, 2020 6:24 am

“He and Porporato previously reported that climate models underestimate the cooling effect of the daily cloud cycle.”

You mean THIS paper on cloud cycles?

“While this model tuning does not seem to invalidate climate projections because of the limited DCC response to global warming, it may potentially increase the uncertainty of climate predictions.”

Well, ok. So, w.r.t. solar power, another source of tipping point pressure?

Peter W
October 8, 2020 6:29 am

About 3 years ago my sister, on a farm in central NH, was approached by a salesman for solar power and asked for my advice. I told her to turn down the offer.

This past year she called to thank me profusely. An acquaintance on another farm nearby had gone for the offer and went 100% solar. They had just experienced 6 straight days of cloud cover and did not have enough electricity for their family of 4 to be able to shower.

Solar minimums, such as the one we have been entering, result in an increase in cosmic rays, and cosmic rays are instrumental in cloud formation, especially as you get further toward the poles. See S. Frederic Singer, “Unstoppable Global Warming,” for a more detailed explanation, plus

Gordon A. Dressler
Reply to  Peter W
October 8, 2020 7:08 am

Tell your sister to tell that acquaintance not to worry . . . the next salesman coming down the road might just be offering a great deal on additional home electrical backup battery units. It’s all just a matter of money, like also needing a room add-on to accommodate those extra batteries.

Pat from kerbob
Reply to  Gordon A. Dressler
October 8, 2020 7:17 am

Perfect textbook example of green energy spreading money through the economy and creating jobs


Reply to  Pat from kerbob
October 8, 2020 2:58 pm

Yeah, just envisage the same salesman with a great deal for a company to remove the solar panels (might even be the same company). After all, who are also going to be the experts at removing all the wind turbines in the future?

Pat from kerbob
Reply to  Peter W
October 8, 2020 7:22 am

You describe what will be the bait and switch at the world level
The thrust behind intermittent ruinable power scam is that breakthrough battery tech is very close
So to save the world we must invest trillions more NOW!!!! in ruinables and the coming battery revolution will solve the grid instability

When that revolution fails to show we will be stuck buying trillions in existing battery tech, destroying the world in the process as decision makers will be unable to admit they went the wrong way in the first place

Max P
Reply to  Pat from kerbob
October 8, 2020 8:40 am

Seems to me that battery technology is pretty mature and there will not be any ‘revolution’ or ‘leap’ in the technology. We’re down to trying to minimize the losses when charging and discharging batteries and making the devices they power more efficient.

Max P

Reply to  Max P
October 8, 2020 11:04 am

There are only a couple of ways to minimize charging and discharging losses.
The first is to decrease the resistance of the internal leads.
The second is to increase the number of internal leads so that more of the battery is reached directly.

Of the first, there are only a few ways to decrease the resistance.
1) Make the leads bigger. This increases the size, weight and cost of the battery.
2) Make the leads out of something with lower resistance. Since they are already using copper, the choices are gold, silver or some kind of exotic alloy. While this doesn’t increase the size of the battery, the weight and cost are definitely going to go up.

Increasing the number of internal leads also increases the size, weight and cost of the battery.

You could also do a mixture of both, however the size weight and cost problems still exist.

Reply to  MarkW
October 8, 2020 11:06 am

And this all still only gets you an extra mile or two on your range.

Reply to  Max P
October 8, 2020 11:05 am

You can also rearrange the geometry of the battery so that the leads can be shorter, however we still need a battery that will fit into a car, while leaving room for passengers and luggage.

October 8, 2020 7:17 am

Yes… climate change causes more clouds where its hot and greatly reduces the wattage of sunlight that penetrates deep enough into the atmosphere to heat the ground and CO2.

Lemme know when the authors figure that bit out.

October 8, 2020 7:35 am

There are no areas “ideal for solar power production”, unless such areas are defined by the availability of subsidies. Kind regards to all participants in the amazing WUWT.

October 8, 2020 7:48 am

Solar power may be worse than we said because of climate change folks.

October 8, 2020 7:50 am

So, less clouds causes warming.
Warming induces evaporation and thus more clouds, and so, less sunny days.

Climate science’s FIRST rule :
– less clowns means less funny days.

Reply to  Petit_Barde
October 8, 2020 8:43 am

This made my day. Thanks. The only way to survive this is…… laughing.

Gary Pearse
October 8, 2020 7:59 am

There is a definite walking-back going on on global warming and renewables. We are seeing uncertainty being injected into both the warming expected and the suitability of wind, solar and biomass. More nice things are being said about nuclear. Mass extinction and tipping points are phasing out of the discussion.

The consensus community has tried to weather a continuing series of near knockout blows over the last two decades:
• 18+ year “Dreaded Pause”
• Climategate
• Frozen out expeditions to find GW in polar regions, including the last German Polarstern failure ‘rescued’ by use of Covid 19 fiction and followed by silence on bitter findings.
• polar bears multiplying (refusal to publish embarrassing survey)
• The surprise of the Great Global Greening of the planet and continuing bumper crops.
• record cold and snowy winters of the last few years – frozen sharks on New England beaches, rescue of hypothermic turtles in Gulf of Mexico.
•First high profile defections, Schellenberger, Michael Moores critical film, etc.

They have found themselves half-heartedly and embarrassingly trying to put over global warming worse-than-we-thought explanations for record cold events. Snow in the Mid East, South Africa…

This is the whimper, there will be no bang.

Reply to  Gary Pearse
October 8, 2020 8:12 am

Not in the UK. BoJo found his windy Mojo and is doubling down on the ‘South Arabia’ of wind power.

Gary Pearse
Reply to  Vuk
October 8, 2020 11:19 am

Boris can say this now (he probably has a cunning reason – is he still negotiating stuff with EU?) but knows he never has to act it out. Gavin Newsom, Calif. Gov is banning ICE cars by 2030, ditto! None of this is going to happen.

Pat from Kerbob
Reply to  Gary Pearse
October 8, 2020 8:36 am

Really hope you are right
But do you think the interests behind anticipated $100 trillion in renewable garbage with gas back up are going to fold that easily?

There is a lot of money on the table….

Gary Pearse
Reply to  Pat from Kerbob
October 8, 2020 11:06 am

Well, we can just crank up gas-fired back-up to 100% and fulfill green job promises by taking down the windmills and solar panels and replanting trees on the landed that 2as tufted and glazed during the manic phase.

Joel O’Bryan
Reply to  Gary Pearse
October 8, 2020 8:55 am

Climate change policy has never been about changing climate. It is about ending western-style capitalist free markets and eliminating an affluent middle class it has created.
The middle class competes for the same resources the elites want reserved for themselves. A middle class that flies on commercial jets for vacation competes for the same destinations as the rich elitists on their private jets. The middle class on cruise ships competes for the same tropical, and exotic destinations as the elitists on their yachts.

Reply to  Gary Pearse
October 8, 2020 9:09 am

Wait until the snow in odd places not only sticks, but starts piling up… and piling up… and piling up… until it’s hip deep in the Sahara and kids can go ice skating on the frozen surfaces….

It’s coming. Must be patient.

Anyone want to make a bet that the cost of eggs at the store may go up? Anyone? Bueller?

October 8, 2020 8:37 am

I wonder if there is big volcano eruption what will happen to solar power of sky is dim

October 8, 2020 8:43 am

It is not the role of solar panels to provide energy to supply demand. That Is the job of the grid.
I have been told this by solar enthusiasts. No problem. Solar and wind are the future. They say.

Trying to Play Nice
Reply to  Billy
October 8, 2020 9:35 am

I had someone tell me on another site that it doesn’t matter if the sun isn’t shining at night, it will be shining on another part of the world. I guess the grid will extend around the world so we can ship those electrons around. Crossing the Atlantic and Pacific will be tricky.

Reply to  Trying to Play Nice
October 8, 2020 11:09 am

There’s always the Bering Straights, however a conductor big enough to power all of the Americas would probably be over 100 feet in diameter.

October 8, 2020 8:43 am

The team used satellite data and climate models to project how sunlight reaching the ground would be affected as warmer global temperatures alter the dynamics and consistency of Earth’s atmosphere.

When I see this statement or anything referring to Models, I question any conclusions given.

October 8, 2020 8:51 am

The team used satellite data and climate models…

climate models underestimate the cooling effect of the daily cloud cycle…

And the novelty of their approach is to say that in some places there is going to be more uncertainty in day-to-day variability,”

A total waste of someone’s money for sure.

Joel O’Bryan
October 8, 2020 9:07 am

solar can never overcome its biggest intermittency— the sunsetting everyday just when most electricity demand is peaking. Useless power that just drives up grid power costs.

Tim Gorman
October 8, 2020 9:18 am

Jeeesh! You’d think it never rains in the summer when the air is hot! But it DOES! At least where there is enough water to evaporate and saturate the air.

Do *any* of these so-called climate scientists actually know what “semi-arid” means?

Reply to  Tim Gorman
October 8, 2020 11:11 am

In tropical or near tropical places, afternoon showers are so predictable you can practically set your watch by them. If anyone still had watches.

Bruce Cobb
October 8, 2020 9:18 am

This “study” receives a grade of “F”.

Reply to  Bruce Cobb
October 8, 2020 12:05 pm

Ahhh.. that means it passed climate science pal-review.

October 8, 2020 9:19 am

So, now we can blame the unreliability of solar power on Climate Change!

Robert Austin
October 8, 2020 9:29 am

Richard Lindzen’s” iris effect” mayhaps? Willis’ tropics climate governor. The great thermal engine with H2O as its working fluid, the variability of cloud cover and the Stephan-Boltzman relation work to make for an extremely stable climate. The only possible alternate state is a flip from inter-glacial to glacial. Carbon dioxide is the pea under the alarmist princess’s stack of mattresses that only the alarmist princess’s can feel.

October 8, 2020 10:25 am

If you look at the data, solar is not that unreliable. On most days, say in CA or the UK, solar gives a reliable, midday boost to the power grid, when power demand is high. That boost only lasts about nine to ten hours, though. Overall, solar is fairly reliable. Wind is the wildcard. It can vary by an order of magnitude over a 24 hour period, with no real connection with demand. That is why electricity at night might have a negative commercial value. The wind is blowing and nobody wants the power. That does not often happen with solar. As for these slight changes in solar power based on computer projections. Please. Keep that nonsense to yourself.

Robert of Texas
Reply to  joel
October 8, 2020 11:13 am

Then DON’T BUILD the stupid solar farms. Problem Solved.

Robert of Texas
Reply to  Robert of Texas
October 8, 2020 11:24 am

This was not meant to be a response to Joel, but a response to the article contents. Not sure why it ended up under Joel’s comment.

Reply to  joel
October 8, 2020 11:16 am

While solar power is superficially related to power demand, the linkage is very weak.
(Note, the following discussion is about averages, depending on where you live and the time of year, your individual situation could be vastly different.)
Solar power peaks at around noon, and drops dramatically on either side of the peak. There is almost no solar power being generated for the first few hours after sunrise and for the last few hours prior to sunset.
On the other hand, summer peak demand usually occur at about the time the sun is setting, and winter demand peaks occur in the early hours of the morning, before sunrise.

You would need huge batteries to store the peak energy so that it would be available during times of peak demand.

And this doesn’t even begin to discuss the problems caused by random clouds.

Robert of Texas
Reply to  joel
October 8, 2020 11:23 am

I don’t know what charts you are looking at, but in Texas the peak electrical usage begins around 4:00 PM and ends around 10:00 PM. Now how useful is solar for THAT?

You cannot just look at how much power a solar grid delivers, you have to match that against peak load. You have to build infrastructure that delivers enough power at peak load, or you have brown-outs and black-outs. Solar is useless for this, so you must develop alternative electrical production with NO solar in mind. The makes solar power extremely expensive, no matter how they try to hide it and spin it in the press.

Building solar capacity, in theory, helps you to not burn gas and coal during peak solar production hours of the day, but since you must have even more power in the evening you still have to build the alternative non-solar infrastructure for it. You can claim you are reducing CO2 from the atmosphere but you really are not when you add in the CO2 to build the solar infrastructure, maintain it, and then dispose of it.

Solar used on household rooftops DOES make sense in some areas – like California where they have an unreliable electrical grid due to mismanagement, poor planning, over reliance on green energy, frequent fires and earthquakes. It is useful in giving the homeowner some amount of alternative local power because of their situation.

Solar farms make NO SENSE. They will continue to make no sense until they solve the power storage and cost problems. The fact solar panels have come down in cost does not solve their cost problem – it’s just part of the cost.

Reply to  Robert of Texas
October 8, 2020 1:50 pm

I’ve lost track of the number of solar energy advocates who actually seem to believe that the output of a solar panel is pretty much constant from sun-up to sun-down.

Tim Gorman
Reply to  MarkW
October 9, 2020 5:22 am

That’s because most solar advocates have no understanding of reality and no understanding of actual math (think angle of incidence). It’s actually a condemnation of our educational system today. If these advocates did even a simple experiment with a solar-powered bobble-head or airplane they would be able to actually experience reality. But they don’t even have the sense to understand what they see.

Eric Vieira
Reply to  Robert of Texas
October 9, 2020 1:13 am

When one considers the total amount of energy that goes into PV production (mining, rare metals, refining the Silicon, connectors, aluminum frames and panels), transportation of the goods from china, rooftop mounting, maintenance and the energy and costs involved for disposal and recycling at EOL; it’s not even sure that they produce during their life-cycle more energy than they have inherently consumed. Maybe in Arizona?

Reply to  Eric Vieira
October 9, 2020 2:09 pm

Don’t forget the energy needed to remove and dispose of the panels.

October 8, 2020 10:25 am

The researchers’ findings were based on probabilistic calculations similar to those used to determine the risk of flooding or drought.

So, how good have THOSE calculations turned out?

October 8, 2020 10:40 am

That claim could be valuable for the fraudsters getting taxpayer grant money from the GND grant program when making excuses for failing to deliver.

Susan Jarvis Bryant
October 8, 2020 10:42 am

Eternal Apocalypse

I’ve managed to escape a coming ice age;
A mammoth hasn’t tossed me to my death.
I’ve dodged the planet’s ozone-waning end-stage;
Our green and pleasant land’s still drawing breath.

The polar bears are plentiful and healthy.
The ocean hasn’t swallowed coastal homes
Of cunning cons who’ve grown yacht-owning wealthy
By dishing fishy gloom—it pays to moan.

I’ve lived beyond Casandra’s worst predictions;
Each year there’s one more fear for seers to stoke.
I’m starting to believe experts’ convictions
Are punchlines to a sick, archaic joke.

Now eons on from each horrific warning,
Unless we all go vegan Gaia fries.
Ingest a burger and we’ll all be mourning—
Our critter-littered Eden curls and dies.

Wild tempests, torrid seas and horrid weather
Will shake our ecosystem to the core,
Then wreck our offspring’s wondrous world forever—
It’s etched in Chicken Little’s book of lore.

I’ve lived beyond the forecasts of extinction,
But now I fear the Reaper’s grimmest knock.
The irony of false prognostication
Is ducking doom to croak from years of shock.

October 8, 2020 11:18 am

Even without clouds, extra water in the air will decrease the amount of sunlight reaching the surface.

Louis Hunt
October 8, 2020 1:35 pm

“Their study found that higher surface temperatures — and the resulting increase in the amount of moisture, aerosols and particulates in the atmosphere — may result in an overall decrease in solar radiation and an uptick in the number of cloudy days.”

So their saying that higher temperatures will result in an overall decrease in solar radiation. Isn’t that a negative feedback? If there is less sunlight hitting solar panels, there will be less sunlight hitting the surface, as well. As I suspected, there will be no runaway global warming because negative feedbacks will help keep the warming in check. If that were not the case, life on our planet would not have survived the high levels of CO2 that existed in the past.

Reply to  Louis Hunt
October 8, 2020 4:10 pm

Louis – spot on! That’s the negative feedback that sceptics have known about for years but that the IPCC and modellers have studiously avoided.

Tim Gorman
Reply to  Louis Hunt
October 9, 2020 5:23 am


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