UW Researchers Find Wildfire Smoke is More Cooling on Climate Than Computer Models Assume

From University of Wyoming

January 12, 2021

The UW Mobile Lab measures biomass burning smoke in Wyoming from a couple of years ago. This is an example of the type of field measurement that was used to compare with the computer models. Hunter Brown, a recent UW Ph.D. graduate in atmospheric science, was the lead author of a paper that revealed that smoke from wildfires has more of a cooling effect on the atmosphere than computer models assume. (Rachel Edie Photo)

A study of biomass burning aerosols led by University of Wyoming researchers revealed that smoke from wildfires has more of a cooling effect on the atmosphere than computer models assume.

“The study addresses the impact of wildfires on global climate, and we extensively used the NCAR-Wyoming supercomputer (Cheyenne),” says Shane Murphy, a UW associate professor of atmospheric science. “Also, the paper used observations from UW and other teams around the world to compare to the climate model results. The main conclusion of the work is that wildfire smoke is more cooling than current models assume.”

Murphy was a contributing author of a paper, titled “Biomass Burning Aerosols in Most Climate Models Are Too Absorbing,” that was published Jan. 12 (today) in Nature Communications, an open-access journal that publishes high-quality research from all areas of the natural sciences. Papers published by the journal represent important advances of significance to specialists within each field.

Hunter Brown, who graduated from UW in fall 2020 with a Ph.D. in atmospheric science, was the paper’s lead author. Other contributors to the paper included researchers from Texas A&M University; North Carolina A&T State University; the University of Georgia; the Finnish Meteorological Institute; the Center for International Climate and Environmental Science, and Norwegian Meteorological Institute, both in Oslo, Norway; the University of Reading in the United Kingdom; North-West University in South Africa; the University of Science and Technology of China in Hefei, China; and Pacific Northwest National Laboratory in Richland, Wash.

The composition, size and mixing state of biomass burning aerosols determine the optical properties of smoke plumes in the atmosphere which, in turn, are a major factor in dictating how these aerosols perturb the energy balance in the atmosphere.

“We found that many of the most advanced climate models simulate biomass burning aerosols or smoke that is darker, or more light absorbing, than what we see in observations,” says Brown, of Juneau, Alaska. “This has implications for the climate predictions made by these models.”

two people in plane cockpit, seen from behind
The National Science Foundation/National Center for Atmospheric Research (NSF/NCAR) C-130 aircraft measures biomass burning smoke during the WE-CAN (Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption and Nitrogen) field campaign in 2018. (Shane Murphy Photo)

Observations and models used in the study covered a wide temporal range. Africa, South America and Southeastern Asia, in addition to boreal fire regions, were chosen because these are the largest contributors to biomass burning smoke emissions in the world, Brown says.

The National Center for Atmospheric Research (NCAR)-Wyoming Supercomputing Center (NWSC) in Cheyenne was used for all of the data processing and the model sensitivity simulations, Brown says. Some of the other model data used for comparison in this study were generated elsewhere.

“When we compare global observations of wildfire smoke to simulated wildfire smoke from a collection of climate models, the vast majority of the models have smoke that is more light absorbing than the observations,” Brown explains. “This means that more energy from the sun is going toward warming the atmosphere in these models, as opposed to what we see in these field campaigns and laboratory studies, which report less absorbing smoke that has more of a cooling effect by scattering light away from the Earth and back to space.” 

How absorbing these aerosols are in the atmosphere depends on the type of fuel that is burning, as well as the climate of the fire region. Generally, hot, dry grassland fires in Africa and Australia tend to have much darker smoke, which is more absorbing, while cooler, wetter boreal forest fires in North America and Northern Asia tend to have much brighter smoke, which is less absorbing.

Full article here.

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Steven Curtis Lohr
January 12, 2021 6:24 pm

Well, that’s some kind of “feed back”, I would think. Gets too hot, makes fire, atmosphere cools. Just a thought. I wonder if it has happened before.

January 12, 2021 6:32 pm

Any solar the smoke reflects results in local cooling. Any solar the smoke absorbs also contributes to cooling since about half of what it absorbs is emitted up into space and does not otherwise affect the surface.

Tim Gorman
January 12, 2021 6:34 pm

The computer programmers and mathematicians building these climate computer models need to get out of their basements once in a while and experience the real world. That’s how engineering judgement gets developed.

The smoke from several of the wildfires wound up in the skies over Kansas. That haze was WHITE, not black or grey. It wasn’t much different in color from water vapor generated clouds.

Grassland fires on the Kansas prairie generally produce white smoke once you are a few miles away from the burn. The darker particles precipitate (is that the right word?) out pretty quickly since they are typically heavier.

Reply to  Tim Gorman
January 13, 2021 11:16 am

and experience the real world.

That seems to be an ubiquitous problem in “academia” in general.

John Bruce
Reply to  Tim Gorman
January 13, 2021 8:59 pm

same in Australia
black smoke fast becomes white
Looking out my window in Perth
irrespective of fire location always gray/ white haze
interestingly sky looks red at night to the naked eye but the camera tells a different story – probably due to infrared reflection into space

January 12, 2021 6:43 pm

This is not necessarily good news. The alarmists can claim that global warming would be worse if not for forest fires.

If I recall correctly, ‘they’ were claiming that Chinese pollution explained why their global warming predictions hadn’t eventuated.

Chris Wright
Reply to  commieBob
January 13, 2021 2:24 am

“This is not necessarily good news. The alarmists can claim that global warming would be worse if not for forest fires.”
Maybe not. I’m pretty sure that wildfires overall have been getting less severe over the last hundred years e.g. in the US wildfires were far worse in the 1930s.
Maybe global warming was actually caused by the fall in wildfires!

Reply to  commieBob
January 13, 2021 11:17 am

would be worse if not for forest fires.

So we need more forest fires to save the world? 🙂

January 12, 2021 6:56 pm

The global energy balance is thermostatically controlled. Heat loss drops off dramatically once sea ice forms at -2C and heat uptake drops off dramatically once sea surface reaches 28C. Open ocean surface loses heat once the temperature exceeds 29C meaning there are only a few nooks and crannies of the ocean surface warmer than 29C where the cloudburst cycle is disrupted by local topography.

The only influence on the global energy balance with regard to land is a portion of the land falling precipitation as it reflects the energy extracted from the oceans by way of evaporation and then released over land as the water condenses then precipitates.

Smoke has local cooling impact over land. Any loss of energy uptake in the oceans due to smoke will be soon compensated by reduction in cloud over tropical oceans.

Climate models are garbage. They are unphysical claptrap based on a fairytale of “Greenhouse Effect”.

John Bruce
Reply to  RickWill
January 13, 2021 9:03 pm

the original experiment was a closed glass box with no heat transfer to the external system
18th century experiment – 21st century monkeys who don’t understand engineering and physics

John F Hultquist
January 12, 2021 7:24 pm

” … more cooling than current models assume.”

Poor wording. People assume, usually to their detriment.

January 12, 2021 7:26 pm

These UW Cowpersons (to be politically correct) are obviously WRONG! Didn’t they get the memo that catastrophic alarmist global warming science is settled and all research results must conform with existing IPCC models unless CO2 is worse than we thought? Please cancel all future federal funding of this University until they comply.

JBdn & KHrs


Not Chicken Little
January 12, 2021 7:35 pm

Wait, what??? They used actual observations and not dueling computer models to figure this out??? Are actual observations even allowed in “climate science”??? Unless you find a good one-off that supports your theory, of course…

D. J. Hawkins
Reply to  Not Chicken Little
January 13, 2021 10:47 am

I pity this Hunter Brown person. Never gonna get another grant. Ever.

January 12, 2021 7:37 pm

Can the smoke from coal fired power plants be tuned to maximize its cooling effect?
Could enough coal power plants be built in impoverished countries to cool the earth?
Sometimes the solution to a problem is staring you right in the face.

Reply to  tommyboy
January 12, 2021 7:51 pm

Modern coal powered fire stations don’t put out much smoke.

Smoke is actually mostly particulate matter and aerosols

These are highly controlled in a modern coal fired power station.

Reply to  fred250
January 12, 2021 8:15 pm

Disable the scrubbers and burn high sulfur coal. This will generate aerosols to cool the earth. Just build very tall emissions towers to prevent the sulfur compounds from poisoning environment.

Reply to  tommyboy
January 12, 2021 7:52 pm

Also, less Green and more green is good for people and the environment.

Peter W
Reply to  tommyboy
January 13, 2021 5:36 am

In the 1970’s the word from the experts was that we were having global cooling, it was all our fault because all the soot in the atmosphere we were emitting was bringing on the next ice age, and we were doomed unless we did something about it.

Tom Abbott
Reply to  Peter W
January 13, 2021 6:38 pm

Yeah, I remember those failed claims.

January 12, 2021 7:47 pm

How can this possibly be true. ????

Fires also emit HUGE quantities of CO2 into the atmosphere,

…. so SHIRLEY, they must heat everything to 1000ºC+, even after the fire has gone 😉

Mike Dubrasich
Reply to  fred250
January 12, 2021 8:52 pm

Last Sept. when a million acres were incinerated in Oregon, the choking smoke filled the valleys. The sun was a dull red, and the temperature plunged 10°-20°F.

On the other hand, more CO2 was emitted that week than all human activities in the state for a year. So maybe in 100 years we’ll get a degree or two back.

January 12, 2021 8:04 pm

UW researchers can now calculate how much the Wyoming Yellowstone wildfire in 1988 cooled the earth by using their coal fired supercomputer. Maybe they can save the earth from catastrophe by burning 🔥 Wyoming forests every 30-40 years.


January 12, 2021 8:45 pm

Good grief!
An article about carbon particles in the air forcing global cooling.
That was a grave fear back in 1971 when Rasool and Schneider (NASA) published a paper on industrially emitted particles of carbon which would screen out the sun and cause cooling.
The threat of cooling and another ice age was very voguish then.
Articles in popular magazines called it “soot”.
Since 1989, James Hansen has been the grandfather of global warming hysteria. And over the past twenty years he has published his concerns that particulate carbon in the atmosphere has been contributing to global warming. Repeat warming.
In thinking back to when “cooling: was a profitable concern for academics I tried to find something by Hansen that carbon particles would cause cooling.
He has been a faddish sort of guy and there might have been the possibility.
Closest I got was a note from Robert Cess. A PhD in physics who had done some work on the upper atmosphere. As well as on the Martian atmosphere.
Sadly, he is still an earnest CO2 warmer acolyte.
The note from Cess was that Hansen provided the “modeling” that Rasool and Schneider used to back their fears about “soot” and cooling.
But Hansen did not state that “soot” caused cooling.

Reply to  Bob Hoye
January 13, 2021 8:15 am

“An article about carbon particles in the air forcing global cooling.”

They say carbon (black, absorbs) is warming, ashes etc. (white, reflect) do cool.

Some decades ago, there was the theory of “nuclear winter” around, i.e. that the soot from the fires resulting from a nuclear world war would blacken the skies and set the remaining life to freeze. Maybe Hansen was involved.

January 12, 2021 8:52 pm

In case you were wondering about the Australian bush recovering from fire-
Bushfire regeneration | Kangaroo Island and Adelaide Hills | SA T… (southaustralia.com)
That will get rid of a lot of pest species that can’t handle intense bushfire while the natives rebound quickly.

Pat from kerbob
January 12, 2021 8:53 pm

Isn’t this simply another method to try to explain why models aren’t reflecting observations

January 12, 2021 8:56 pm

“The study addresses the impact of wildfires on global climate,”

Ok, can someone please remind these people the meaning of the word climate?

Rory Forbes
Reply to  Mike
January 12, 2021 9:23 pm

As long as they insist that this planet has a single climate capable of being studied and remain committed to the fallacy that a climate can be as short as 30 years … no, they have no idea what climate means.

Harri Luuppala
Reply to  Rory Forbes
January 12, 2021 9:59 pm

Anyhow on addition to wildfires there are 200 – 500 million people using slash-and-burning (if you can trust to wikipedia…). As a Finn it is new info in this wiki arcticle for me that in Finland we have an open-air museum where they still practise slash-and-burn agriculture. https://en.wikipedia.org/wiki/Slash-and-burn

Peta of Newark
January 12, 2021 9:16 pm

“”The main conclusion of the work is that wildfire smoke is more cooling than current models assume“”

What is the mechanism by which computers (machines) make ‘assumptions’?
People Make Assumptions.
Also they indulge in Conclusion Jumping, Confirmation Bias and Magical Thinking
Machines cannot and do not, unless told/programmed to.

Thus we see, yet again, how The Human Animal cannot pass off untruth.
It always gives itself away

This a Junk Science par excellence and we’ve just been told as much by one of its self-professed experts.
Thank you kindly.
Now tell me something new, as what scientists/teachers are supposed to do.

PS Is not a major parts of the smoke clouds what is commonly called ‘steam’ – tiny droplets of condensed water vapour?
And is what ordinary clouds are made of and, ordinary clouds, contrary to popular belief (assumption) are always intensely dazzling white
Its that photographer’s trick of looking at the flue stacks and cooling towers of power stations.
Get the light & camera-angle right and the stuff coming off them looks to hideously planet-wreckingly black

January 12, 2021 9:29 pm

CAGW is all smoke and mirrors…

During the 1945~1978 PDO 30-year cool cycle when global temps were falling, climate alarmists hacks blamed manmade coal particulates for the cooling and predicted a New Ice Age…

When the PDO switched to its 30-year warm phase in 1979, the same alarmists hacks blamed manmade CO2 emissions for the warming and predicted catastrophic 3C~5C of manmade global warming by 2100.

Now that reality doesn’t come close to matching the alarmists’ absurd warming predictions, they’re now blaming manmade wildfire cooling as the reason their insane warming predictions are so completely devoid from reality…

Once the 30-year PDO/AMO cool cycles restart, it’ll be interesting to see what excuses Leftist alarmists make for the coming global cooling…

Leftists are truly evil…

Peter W
Reply to  SAMURAI
January 13, 2021 5:45 am

You can also blame the media. Keep in mind that the media survives by selling news and taking in advertising. What type of news sells? DISASTER! So the media has every incentive to report disaster-type news, for example climate change (warming causes flooding, cooling will bring on an ice age). Don’t expect unbiased articles on climate change from the popular media, whether it be newsprint or TV.

January 12, 2021 10:03 pm

So recent 20th century mechanization of firefighting, and reduction of aboriginal animal herding fires on prairie and woodlands, and clearing continental plains of trees to become farmland in the 1800’s have resulted in global warming in the last 100 years’ thermometer record ? Since thermometers were only invented in 1714 and weren’t very accurate for the first 100 years.
Whoddathunkit ?

Jean Parisot
Reply to  DMacKenzie
January 13, 2021 6:40 am

Add in the distribution of thermometers and temperature records spatially coincides with anthropogenic land use changes. Backing that institutional bias out of the baseline produces uncertainty that exceeds natural variability.

January 12, 2021 10:22 pm

The problem with computer models..

A human wrote the code and humans input the data, shit in, shit out.

michael hart
January 13, 2021 1:18 am

“How absorbing these aerosols are in the atmosphere depends on the type of fuel that is burning, as well as the climate of the fire region.”

Which is just what I assumed before I even read the first line of the article.

The title of their paper really ought to be something like “We don’t yet know how to accurately distinguish one type of smoke from the other 49 types, but hey, here’s some computer modelled garbage to keep you distracted until we’ve had a few more decades to think it over.”

January 13, 2021 3:41 am

70% of the globe is covered in clouds at any one time, which I understand is not included in the climate models. Shouldn’t these “climate scientists” address the elephant in the room rather than the mouse in the corner?

Peter W
Reply to  RockyRoad
January 13, 2021 5:53 am

Addressing the elephant in the room is exactly what S. Frederick Singer did in his co-authored book “Unstoppable Global Warming Every 1,500 Years.” And that, of course, is why he has been both vilified and ignored ever since! I started studying this climate change business back in 2006, was a physics major in college, listened to both sides of the issue, checked references, studied more science AND history, and quickly came to the conclusion that climate change is natural.

Reply to  RockyRoad
January 13, 2021 6:37 am

Clouds are parameterized in the models…just too difficult to compute….that means they are correlated to a couple of variables that don’t change much so that the model is computationally stable. Unfortunately real cloud cover forms on a scale of 1 km to 5000 km and exists for a couple of hours to a few weeks, is often self propagating until precipitated out, and forms in a turbulent and chaotic troposphere where cold air is trying to fall, warm air is trying to rise, and coriolis forces are pushing air sideways. Best correlation is to precipitable water, which correlates to ocean surface temperature, but that results in a constant surface temperature, so renders the model inoperative for things like volcanic dust, which climate scientists are sure affect the climate. Although playing “pick the eruption date” on a global temp history graph seems to have high uncertainty when profs try it on their students,,,.

January 13, 2021 6:07 am

So they found out it’s cooler in the shade. Who would have thought.

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