New study shows impacts of increased levels of evaporative demand as climate grows warmer and drier
DESERT RESEARCH INSTITUTE
Reno, Nev. (Nov. 19, 2020) – Climate change and a “thirsty atmosphere” will bring more extreme wildfire danger and multi-year droughts to Nevada and California by the end of this century, according to new research from the Desert Research Institute (DRI), the Scripps Institution of Oceanography at the University of California, San Diego, and the University of California, Merced.
In a new study published in Earth’s Future, scientists looked at future projections of evaporative demand – a measure of how dry the air is – in California and Nevada through the end of the 21st century. They then examined how changes in evaporative demand would impact the frequency of extreme fire danger and three-year droughts, based on metrics from the Evaporative Demand Drought Index (EDDI) and the Standardized Precipitation Evapotranspiration Index (SPEI).
According to their results, climate change projections show consistent future increases in atmospheric evaporative demand (or the “atmospheric thirst”) over California and Nevada. These changes were largely driven by warmer temperatures, and would likely lead to significant on-the-ground environmental impacts.
“Higher evaporative demand during summer and autumn–peak fire season in the region–means faster drying of soil moisture and vegetation, and available fuels becoming more flammable, leading to fires that can burn faster and hotter,” explained lead author Dan McEvoy, Ph.D., Assistant Research Professor of Climatology at DRI.
“Increased evaporative demand with warming enables fuels to be drier for longer periods,” added coauthor John Abatzoglou, Ph.D., Associate Professor with the University of California, Merced. “This is a recipe for more active fire seasons.”
The research team found that days with extreme fire danger in summer and autumn are expected to increase four to 10 times by the end of the century. Their results also showed that multi-year droughts, similar to that experienced in California and Nevada during 2012-2016, were projected to increase three to 15 times by the end of the century.
“One major takeaway was that we can expect to see a lot more days in the summer and autumn with extreme fire danger related to increased temperature and evaporative demand,” McEvoy said. “Another takeaway was that even in locations where precipitation may not change that much in future, droughts are going to become more severe due to higher evaporative demand.”
Study authors say that the cumulative effects of increases in evaporative demand will stress native ecosystems, increase fire danger, negatively impact agriculture where water demands cannot be met, and exacerbate impacts to society during periods of prolonged dryness. Several members of the research team are part of the California-Nevada Applications Program (CNAP), and will use these study results to provide resource managers with a view of possible future scenarios.
“These results provide information to support science-based, long-term planning for fire management agencies, forest management agencies, and water resource managers,” said coauthor Julie Kalansky, Ph.D., Program Manager for CNAP. “We plan to work with partners to help integrate the findings from this paper to support building climate resilience.”
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Additional Information:
This study was funded by the National Oceanic and Atmospheric Administration (NOAA) California-Nevada Climate Applications Program (CNAP) and the NOAA National Integrated Drought Information System (NIDIS) California-Nevada Drought Early Warning System.
The full text of the paper, “Projected Changes in Reference Evapotranspiration in California and Nevada: Implications for Drought and Wildland Fire Danger,” is available from Earth’s Future: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020EF001736
The Desert Research Institute (DRI) is a recognized world leader in basic and applied interdisciplinary research. Committed to scientific excellence and integrity, DRI faculty, students, and staff have developed scientific knowledge and innovative technologies in research projects around the globe. Since 1959, DRI’s research has advanced scientific knowledge, supported Nevada’s diversifying economy, provided science-based educational opportunities, and informed policy makers, business leaders, and community members. With campuses in Reno and Las Vegas, DRI serves as the non-profit research arm of the Nevada System of Higher Education. For more information, please visit http://www.dri.edu.
More CO2 lead to better usage of water by plants…
Yep, and at a percentage greater then any modeled loss due to CO2 increase.
However it is a certainty that CA will have more ( is that a synonym for additional) multi year droughts. Also, as CA has been in a relatively wet period for the past 80 years, it may actually experience an increase in droughts. However that would be nothing outside of normal, and hopefully we can avoid the normal multi decade droughts that have occurred in California over the last 1,000 years.
Curious if they considered the projected increase in WV into their modeled assumptions?
CO2 both feeds plants and allows them to use water more efficiently by reducing the time their stomata are open. One thing I haven’t heard people looking into in these states is whether that translates into more understory growth during the winter rainy season and if that contributes to the fire season once things do dry out in the summer/fall.
Does anyone know of research in that direction?
The big scary temperature increases that the alarmists have been warning us about were all caused by the assumption that relative humidity will stay the same as the climate warms. If RH stays the same, then there is no increase in “evaporative demand”. So no problem.
On the other hand, if RH drops, then there is no big increase in air temperature, once again, no increase in “evaporative demand. Again, no problem.
Can’t these morons coordinate their lies?
If it warms significantly without a corresponding increase in humidity, isn’t the AGW hypothesis invalid?
That is the point that I was trying to make.
Brilliant
They neatly describe the positive feedback that creates a desert – once the tress have been cut burned removed and the resulting grassland ploughed ploughed tilled cultivated re-cultivated tilled some more ploughed ploughed again again and again grazed overgrazed etc ad infinitum
Would it not be best to have never ventured near that less-than-happy little cliff-edge first?
Be careful in your definition of A Desert
I don’t wanna know about its weather, climate, how hot/cold it is, what plants do/don’t grow there
Take The Definition of A Desert as= “A Place Of Low or Very Low Soil Organic Matter”
Get my drift……….
My impression is, there are “scientists” first looking for “where can I blame climate change” and than start to specify their research.
I don’t know, Krishna, the Desert Research Institute (DRI — get it?) seems inordinately modest about their self-referenced accomplishments. After all they are a recognized world leader in basic and applied interdisciplinary research . . committed to scientific excellence and integrity . . having developed scientific knowledge and innovative technologies in research projects around the globe . . and informed policy makers. They seem to have left out the ‘Masters of the Universe’ bit, but we shall no doubt be hard pressed to gainsay the certainty of their projected model of conditions 80 years hence, though I am left to wonder just how well their masterful outputs have matched the past century or two for a start.
The time, to accept that “informing policy” is a good reference is unfortunately over since years. It may even be seen as a bad reference, at least it’s my view and experience ober yesrs.
And if you read the comments here about the flawed paper you may realise, these guys would better not inform policies.
How many crystal balls do these guys play with ?
Or is it down using tarot cards?
It sure isn’t anything resembling actual science. !
It is just that I wish they would play with their own balls….
And of course, there has been NO WARMING in the USA since 2005, except a tiny bulge since 2015 from the El Nino /Big Blob solar ocean warming.
….. and current temperatures are similar to those in the 1940s
So whatever they have asked their climate models to produce is just straight, intentional GIGO
Does anyone have the raw temp data for California and or Nevada from say 1900?
Tony Heller’s software gives you all the raw data from US stations. It easy to down from his site. The data from 7 station in CA that are part of the CRN are easy to download. Not surprising, none of the stations have a significant positive time trend in temperature. You would think Gov Newsom would be called out on his inaccuracies about climate and wildfires.
Yep, and at a percentage greater then any modeled loss due to CO2 increase.
However it is a certainty that CA will have more ( is that a synonym for additional) multi year droughts. Also, as CA has been in a relatively wet period for the past 80 years, it may actually experience an increase in droughts. However that would be nothing outside of normal, and hopefully we can avoid the normal multi decade droughts that have occurred in California over the last 1,000 years.
Curious if they considered the projected increase in WV into their modeled assumptions?
“However it is a certainty that CA will have more ”
Let me fix that. However it is a certainty that CA will again have, just as it has had in the past, multi year droughts.
This is confusing me for two reasons.
1) As Krishna Gans says, more CO2 diminishes evaporative demand per volume biomass.
2) Increased heat evaporates more CO2 and H2O from the oceans, which increases the possible availability of of water vapor.
Acknowledged that long periods of drought could offset the improved condition, but these clairvoyant people have difficulties foresee much more than 10 days ahead, thus no practical idea about how the long term, 5, 10, 20 year situation will develop.
Or, maybe it is just me who is naive.
Do these researchers also look at weather patterns ?
They are claiming that as air warms, the relative humidity will drop.
On the other hand, in order to get the scary climate numbers, ALL of the climate models assume that as the air warms, relative humidity will stay the same.
This study directly assumes that every single climate model is wrong, and drastically so.
PS: Without the added water vapor in the air, the atmosphere doesn’t warm by more than a tiny amount, so the dramatically drier air that this study is assuming can’t happen either.
> ALL of the climate models assume that as the air
> warms, relative humidity will stay the same.
and
> This study directly assumes that every single
> climate model is wrong, and drastically so.
This is simply not true. Relative humidity is a resultant variable. Actually, what they assume is CO2 emission and stuff like the shape of the Earth.
> Without the added water vapor in the air, the
> atmosphere doesn’t warm by more than a tiny amount
Warmer air can be dryer even if there’s more water vapor in it, and water’s greenhouse effect is a function of absolute content not relative humidity. Furthermore, air can hold cc. exponentially more water when warms (amount roughly doubles per 11C of change) so even small increases in temp can have quite dramatic effect on dryness. A few C of change in the average can mean much greater differences on summer days, increasing the number of fire hazard days in turn.
Hold on……. I thought the feedback was that water vapor would increase in a warming world.
But then, this was just a “if ” / “then” projection with no proof that the “if” will actually happen.
Wait one,
Wasn’t the ‘water vapor feedback’ system supposed to keep the relative humidity the same? And that additional water vapor supposed to double, triple, quadruple (or whatever) the ‘heating’ due to an increased CO2 concentration?
Or is this one of those ‘local’ events which doesn’t affect the ‘global’ average?
Best,
Willem
If the atmosphere us drying, then the heat content is going down and there is no global warming. This: “According to their results, climate change projections show consistent future increases in atmospheric evaporative demand (or the “atmospheric thirst”) “ is a squirrel, mislabeling what they say to hide the meaning.
Actually, many warmists have said that the additional water vapor will cause more rain and increased damage from flooding. Sounds like the warmists are again trying to have it both ways. What it really means is that they don’t have a clue. It is obvious that they didn’t think the lapse rate would result in more clouds from more water vapor, thereby reducing heat.
In a warmer world there’s more evaporation from the ocean. The atmosphere then isn’t thirsty any more. I would have to look for it to check, but memory tells me it’s all in the IPCC reports. This paper is total nonsense, and the sad part is that because it’s all model prediction it can’t be checked and it will be years before it can be tested. By then everyone will have forgotten it anyway. The best place for it is in the bin. Before publication would have been better.
PS. I have such a low regard for this paper that I suspect the authors realised that more notice would be taken of a paper that predicted things would get worse than of one that predicted things would get better. Am I allowed to enquire whether someone paid them for it? With the widespread parameterisation of the models (that’s definitely in the IPCC reports) you can get any result you want. This must be the result someone wanted.
“The best place for it is in the bin”
The best place for it would be in the outhouse if anyone still has one.
Bring back the outhouse! But none of them fancy, new-fangled two-holers. Nope. Because by the time you decide which one of them holes to sit on, it would just be too late, that’s all.
Funding by NOAA and CNAP
Both, spec humidity and rel. humidity are not constant, it’s an up and down over the years:
Spec hum. 300mb
Rel. hum. 300mb
both 1/1948 – 10/2020
A “thirsty atmosphere”? Talk about being clueless.
If those ridiculous clowns are the greatest scientists on the planet then they are right :
– we are doomed.
“New study shows impacts of increased levels of evaporative demand as climate grows warmer and drier”
These guys obviously haven’t looked at a global temperature chart lately. If they had, they would see that the temperatures have been cooling for the last five years. So their theory just evaporated away.
http://www.drroyspencer.com/wp-content/uploads/UAH_LT_1979_thru_October_2020_v6.jpg
Another case of a climate scientist assuming things not in evidence. They have it in their heads that it is continually warming, so they either don’t look at a global temperature chart or they ignore reality.
Yes, the trend has been a warming trend since the 1980’s, but it has run out of gas when it hit the turn of the century and after the big El Nino of 2016, the temperatures have been cooling, yet these climate scientists stll claim it is warming, and insinutate that it will get even warmer, without evidence.
If the atmosphere is getting more thirsty, it just needs to drink more Dos Equis. But actually, I think it is more hunger than thirst that afflicts it. It clearly wants to chow down on more “carbon”.
OK, I live in a zone officially a desert, the flat ground before the pre-cordillera in Mendoza, Argentina. Enterprising Europeans damned up the river and set up an irrigation system and grew grapes, not those thompson seedless here. We were three years into a drought and the talk of global warming was at a fever pitch. Then in four days in early November we got nearly half of an average years rainfall. Drought to flood. Model that.
The authors also fail to understand 1-hour fine fuels. The grasses and most of the weeds in the “Mediterranean climate” part of California go dormant after their burst of spring growth utilizing the winter precipitation.
The above ground dormant portion of the plants have no moisture of their own and therefore WILL ALWAYS READILY BURN. The only exception is when they have morning dew, but by definition they will equilibrate with the atmosphere within 1 hour.
These fuel sources are already 100% flammable, except for a brief period of time near the crack of dawn on the days when atmospheric conditions did allow dew to form. I believe very few wildfires form at this time (less human activity, lightening, wind-blown utility lines).
Changing the climate CANNOT make the fuel sources any more flammable than 100%!
Exactly my thoughts. They did not take into account the vegetation itself. It is flammable every year after the dry season. Far more important is keeping the fuel load down.
Look, I dont want to give the impression that I buy into what this paper is selling, but the fine fuels is far from the whole story regarding drought and fire.
Not sure what the terms are elsewhere, but in New Zealand we have a concept called Duff Moisture Code (DMC), which is a measure of the moisture content of larger fuels and upper soil layers, and will go from low to high over weeks in a drought, and DC , which is the Drought Code, which is a measure of seasonal drought in deeper compacted layers. Is everybody aware that in drought, the topsoil will actually burn??
So, the fine fuels moisture content will determine how easily a fire will ignite, and once started, how fast it will spread. This can go from low to high in days, and at any time off year. Temperature has little to do with how easy it is to ignite fine fuels.
Once established, the persistence , rate of spread, and difficulty of suppression is largely controlled by Available Fuel loadings, and that is a function of fuel density, how dry it is, wind spead, and topography.
Note again, very little effect of temperature – except in relationship with relative Humidity between day and night.
Wildfire intensity is all about fuel availability (how much and how dry), wind and topography. If you want to control fire, you have to separate the fuel from the fire.
Drought does have a huge effect, but there is little if any evidence that we have or can have any influence on droughts. The other huge factor is fuel loading, and we most certainly can and do have an enormous effect – dare I say control- over that factor.
And this biggest detrimental effect is due the the Green mantra over recent decades of locking up forested areas, and allowing fuel loads to increase.
Does anyone have access to a database of “atmospheric water vapor” at various altitudes in the Western deserts?
Reanalysis data can be plotted up using relative humidity or specific humidity at various levels or can plot precipitable water.
https://psl.noaa.gov/cgi-bin/data/timeseries/timeseries1.pl
3 of 5 authors from where they used to be the leaders in oceanography, didn’t have the goal of saving the world. (Division of Climate, Atmospheric Sciences, and Physical Oceanography, Scripps Institution of Oceanography, University of California, San Diego, San Diego, CA, USA). Justify it as interdisciplinary, I missed the physical oceanography.
“Consecutive drought years are more harmful to ecosystems and water infrastructure than isolated years……The future projections of ET0 [reference evapotranspiration] discussed here expand our understanding of possible drought and wildfire potential in California and Nevada, providing resource managers with a more holistic view of possible future scenarios.” “The authors declare that they have no conflicts of interest”
LOL! Coming from DRI this should be no surprise. No problem, no funding. ….. This is why we have lots of problems. The CMMP (Could-Might-Maybe-Possibly) index is 100% on this report.
.. After working at UNR (DRI’s sister agency) for 28yrs, nothing surprises me…
“We plan to work with partners to help integrate the findings from this paper to support building climate resilience.”…. Masters of rhetoric
Climate Change doesn’t cause the fires under study. Man does. Take man out of the equation and reduce wildland fires by 85%.
First they told us that warmer air was going to absorb more water vapor, and all this extra water vapor was going to make the atmosphere warm to dangerous levels.
Now they are telling us that warmer air doesn’t absorb more water, which causes it to dry out plants.
So if warmer air doesn’t absorb more water, then the only thing we have to worry about is the 0.7C of warming that CO2 by itself is capable of causing, which by itself is a big nothing burger, so there never was a reason to panic in the first place.
I’m going back to sleep.
It does get confusing doesn’t it?
We’re told that a warmer world will mean more H2O in the atmosphere, which will bring bigger storms & floods, but now apparently this same warmer world will instead bring dry conditions & fires.
What are we supposed to tell the kids to expect?
“What are we supposed to tell the kids to expect?”
No matter what happens, they can expect more socialism.
Because no matter what the problem, more government is the solution.
If you look at the study, use the search terms CMIP and RCP. You will find that the researchers ran the CMIP5 models and RCP4.5 and RCP8.5. The CMIP5 overshoot observed warming in the tropical troposphere by 200-300 percent (https://www.thegwpf.org/content/uploads/2019/10/Christy-2019A.pdf). RCP8.5 is a worst case forcing trajectory (emissions scenarios) purporting to be a business-as-usual baseline (https://cedmcenter.org/wp-content/uploads/2017/08/Why-do-climate-change-scenarios-return-to-coal.pdf). So, like so many other worse-than-we-thought studies, this one runs overheated models with an inflated emissions baseline.
That was going to be my comment/observation on the author’s use of RCP 8.5. The scenario is totally disproven and unrealistic even when it was concocted for the AR5/CMIP5 Climate Dowsing dog-and-pony shows.
But RCP8.5 has a clear deceptive purpose. It’s purpose is to allow other disciplines to use it to claim measurable environmental/ecosystem impacts in the modeled in silico Hellscape that level of forcing might produce. They don’t even care about honesty anymore. It’s all a PR salemanship game of misinformatiuon. That’s because the fact that it is unrealistic is not discussed, they just use it to get media attention, papers published, and Ride the Climate Gravy Train to grant success.
Add this to the list of things caused by Global Warming:
Water vapor in the atmosphere will increase
Water vapor in the atmosphere will decrease.
There. Covered all my bases.
What unmitigated BS.
No, DrEd, you haven’t covered all the bases
You missed out on the really alarming scary one.
Water Vapor in the atmosphere will stay the same. !! 😉
Seeing as this is allegedly in the future, it’s not evidence of a thing. But speaking of droughts, how about 200 yr droughts? https://realclimatescience.com/2018/02/science-man-made-california-droughts/
“elevated co2 concentrations from unabated anthropogenic emissions, could, in water limited situations, directly promote vegetation growth and contribute to greening of arid to semi arid landscapes.”
https://www.sciencedirect.com/science/article/pii/S2590332220301007
It’s actually over-population that’s the problem. Lots of songs going way back – “It Never Rains in Southern California!”
Actually, you are spot on right about being over-population. California doubled its population over the last 50 years without adding additional dam type water storage. by their own actions they have doubled the risk in a very measurable action/inaction. The state technocrats and study think tanks will not go there however because its hard work.
NOAA is part of the problem, as they distribute federal grants to the universities and think tanks to write reports examining problems that support prevailing wisdom. Take away the grant money and folks will work on real issues
Dear Mr Rotter
“Climate change and a “thirsty atmosphere” will bring more extreme wildfire danger and multi-year droughts to Nevada and California by the end of this century, …”
I am guessing the authors are probably over the age of 20 and therefore will most likely be comfortably dead “by the end of this century”, so no need for them to worry about being held to account for their forecasts.
Extreme wildfires in California and Australia are substantially due to lack of proper forest management, including controlled burning to reduce fuel loads, something that has been known about in Australia since the 1930s. They don’t seem to have learned the lessons in Australia, they do not appear to have learned the lessons in California: nothing will change, and “extreme” wildfires will continue at regular intervals and people will die, while politicians, bureaucrats and greens bicker.
Nothing will change until the politicians, bureaucrats and greens die from their own actions.
DP