From USC and the evapotranspiration cools locally department:
Hidden, local climate impacts of drought-friendly vegetation
New research by USC Viterbi researchers explores the climate impact of drought vegetation efforts
To address the recent drought in California, policymakers have created incentives for homeowners to replace existing lawns with drought tolerant vegetation. However, new research from George Ban-Weiss, an assistant professor in the Astani Department of Civil and Environmental Engineering at the USC Viterbi School of Engineering, has found that these efforts might have some hidden consequences on local climate.
Ban-Weiss and post-doctoral scholar Pouya Vahmani used a model of the Los Angeles basin to investigate the climate impacts of widespread adoption of drought tolerant vegetation. Their findings, put forth in the article “Climatic Consequences of Adopting Drought Tolerant Vegetation over Los Angeles as a Response to the California Drought” in the journal Geophysical Research Letters, indicate that in fact, if all lawns were replaced with drought tolerant vegetation, that Angelenos could expect an average daytime warming of 1.3 degrees Fahrenheit due largely to decreased evaporative cooling, as irrigation is stopped. For the hottest regions of the Los Angeles basin, such as the inland empire and San Fernando valley, the researchers predict a daytime increase in temperature of 3.4 degrees Fahrenheit. Such temperature increases could exacerbate heatwaves, increase photochemical smog production, and increase air conditioning energy use.
However, one effect of widespread planting of drought tolerant vegetation– which the researchers believe could counteract these higher daytime temperatures– is an even greater decrease in nighttime temperatures. The researchers forecast that the average nighttime temperature decrease could be as much as 6 degrees Fahrenheit. Lower nighttime temperatures are important for preventing adverse human health consequences like heat stroke or even death during heat waves, says Ban-Weiss. People, especially vulnerable populations like the elderly, need temperatures to reduce sufficiently at night to allow their bodies to recover from high daytime temperatures and prevent heat-related illness.
“Our interest in this topic was initially piqued because we hypothesized that the reductions in irrigation associated with adopting drought-tolerant vegetation would cause temperature increases,” says Ban-Weiss. “We were surprised to find the reduced temperature signal at nighttime. But this actually has a simple physical explanation, since reducing soil moisture decreases upward heat fluxes from the sub-surface to the surface at night, subsequently reducing surface temperatures.”
“Our research highlights how water and climate are intimately coupled,” says Ban-Weiss. “You can’t change one without effecting the other.”
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No apparent reason given why they can’t call it “desert vegetation.”
What happens to the nursery stock they shipped from Phoenix to S.C. when the weather swings back to monsoon and washing rains? Oops! “We are once again stocking local species” Cha-ching!
Hey if you turn your front lawn into a desert by planting rocks in place of grass, you probably won’t get dew on them in the morning.
We have plenty of desert. Don’t need to plant any more. Might as well have a Monsanto Astroturf Lawn.
g
“Might as well have a Monsanto Astroturf Lawn.”
I knew a pipefitter in Wood River IL that did that, George.
RIP Larry Reynolds, The icon of Phil’s Tavern.
Many are the Astroturf lawns being installed in San Jose,CA., though tasteful rock arrangements are more popular. My dog prefers the Astroturf particularly if butt-dragging seems indicated.
The ‘apparent reason’ may be that it is hard to sell someone a “desert” for their garden, when their lawn has already turned into a desert. If you call it “drought resistant vegetation” in a state which has been having an extended drought, you may manage to make it look like a selling point.
What someone needs to come up with is biodegradable rocks . That way you need to come back every couple of years to buy some more.
Selling someone a box of rocks and a few cactii is a once only sale. Very bad business model. Where are these guys educated? This is not a ‘sustainable’ model, where are the ‘green’ jobs.
Biodegradable and GMO free, naturally fresh rocks should market nicely!
“What someone needs to come up with is biodegradable rocks . That way you need to come back every couple of years to buy some more.”
We’re likely to see rocks with embedded “killer chips” in them, which will rock on for a predetermined span of time or rock cycles. These rocks will start blinking near end of rock-life, embarrassing you in front of the neighbors and generating a rock re-up reminder on your screen if you have downloaded and installed the 50 megabyte rock awareness app that also sets your homepage to Rock Search and installs the ‘Ask Toolbar’ again.
Every quirk of evolution for the last 30,000 years has been driven by the ‘Ask Toolbar’ and its need to have a host species that will continually install it.
It’s called an extended drought nowadays when a population stops watering a desert, is it? I’ll have to think about the slogans to market that.
40 years ago in California they were selling Pet Rocks. I’m sure someone just found all the unsold inventory and decided to now sell them by the box to clear them all out.
What about pet rocks?
I had wondered about the local effect of those hard scape drought tolerant landscapes. I figured it would make it warmer around the house that used it but this is interesting that it has a broader impact on the local microclimate.
And yes I’ve always know that man modifies the microclimate around his immediate area. I live up by Anthony and was very young when Lake Oroville was built. I remember how the general climate changed slightly with the filling of the lake. So I’ve always known that man generally could have some impact on the local climate. I question though that the change in microclimate around Lake Oroville impacts the climate of say Denver Colorado or St. Charles Missouri.
Plant more trees…
I can tell you from experience that the climate of St. Charles MO is more highly affected by what happens to the east a few miles in Ferg… Oh! The weather type climate… that has more to do with the river and the I-70 corridor on a microclimate scale. It’s interesting to watch rain form in MO along the I-70 corridor.
Do they still mow the lawns short there, so you can see the Ozarks ??
g
It’s the old wagon trail, as you may know. barely north of the Ozarks and comparatively high and flat. Eisenhower’s engineers had some common sense, even though the weather follows the same path.
St. Charles is now a thriving tourist and entertainment area, linked to Grafton, IL by a ferry on weekends for those who also want to enjoy the river bluff life. Sure would like to show anybody around who happens to be in the STL vicinity, Particularly our host and contributors.
I know a couple of kids who were born in St Charles MO. Well they were kids once.
g
It took complex modeling to figure out that arid climates (deserts) have greater temperature swings than moist (tropical) ones.
Strange how that “greenhouse gas” (water vapor) COOLS?!?
How much per year are these universities charging again?
Next their going to discover that water is wet. /sarc
But doesn’t CO2 trap the heat? Why should it get cold at night? This is what my warmist ‘scientific’ friends tell me.
Curious the way they try to explain the cooler nights by less heat being able to come up from deeper in the ground. I had to read it several times to make sure that is was not a typo. saying the opposite of what it meant.
Less humid air at night mean MORE heat from the surface can escape into the night sky. This is why deserts are cold and I think this has been known for decades.
But that is 0.7 deg C, and we are already at 1.3 deg C of warming. That means fully 2 deg C in California and, as we all know, that is the “threashold” at which all hell breaks loose, the climates “dangerously” unstable and thermagedon begins.
It is sufficient to CAL to go unstable and it could trigger a global apocalypse.
WE MUST ACT NOW !
Unfortunately for us at the gateway to the west, this summer moisture is adding to the temperature at night. Weather’s like Real Estate, timing and location are everything.
Lower humidity means less dew condensing at night. When dew condenses, it releases heat, warming the ground, and the air near the ground. So when the humidity is lower, temperature drops faster at night.
“””””….. When dew condenses, it releases heat, warming the ground, …..”””””
Better rethink that.
Water vapor DOES NOT condense until it has already gotten rid of ALL of the latent heat of evaporation. Presumably it reaches the dew point temperature before it reaches the surface so it will be at the (local) air temperature.
The ground may or may not be warmer than the air Temperature, but it would seem that the condensation substrate (ground or grass) must essentially be at the dew point Temperature before the vapor can condense.
I’d be really happy to read a peer reviewed paper and perhaps corroborating similar papers providing actual measured temperature of a surface that increases in temperature immediately after dew deposits.
Yes steam will burn you , but that is because it is at a temperature way above your skin temperature, so your skin is the heat sink which sucks out the latent heat to cool the steam down to where it might condense on you.
The steam is not in thermal equilibrium with the ambient air.
G
good grief….climate science has been reduced to nit picking
Thanks a good thing…….
1 if
4 coulds
1 might
1 surprised
1 predict (not project!)
1 finding of the obvious; “Our research highlights how water and climate are intimately coupled,” says Ban-Weiss.
Southern California is a natural desert.
http://users.humboldt.edu/ogayle/hist383/LosAngeles.html
Well, actually, the places most people live in in SoCal are all > 10 in / year. Most are in the 13 – 14 in / year arena, and some are even above that. Which leads to what one would expect – prairie, oak savanna, chaparral and coast sage scrub. Not desert.
James you are correct and also too nice. When I first moved to a semi-arid area, I was corrected many times before I stopped calling a desert.
Bobby is an idiot. Why? He did not read his own link which states there is a desert east of LA.
Nothing says
Get Off My Lawn
like a bunch of spiny cactus plants.
Raising scorpions as a hobby is a bonus, TonyL.
Heck! You don’t really need the scorpions, just a sign with “BEWARE OF THE SCORPIONS.”
…Your afraid of a rock band from Germany ?
Scorpions, small stuff. Go for the real thing:
Mojave Rattlesnake
Sidewinder
Speckled Rattlesnake
Western Diamondback Rattlesnake
You two guys are just brutal on the gardeners.
Tarantulas. When I was a kid we lived in Taft (just N. of LA), my dad worked for Standard Oil’s communications division, microwave stuff. Anyway, we’d hunt tarantulas under our front porches in the morning, then in the afternoon we’d all get together in some shady place and hold tarantula wars.
Not sure scorpions would have kept us out of your front yard. Might have done the exact opposite. “Unintended Consequences”.
“You don’t really need the scorpions, just a sign with “BEWARE OF THE SCORPIONS.””
Funny that someone else immediately thoughts of rattlesnakes, because I was wondering how a ” Please Do Not Feed The Rattlesnakes!” sign would work out for keeping people off your poppity?
Here in Florida, I am not sure how successfully the “Do Not Feed Alligators” signs work for keeping people from feeding them, but I bet it keeps people out of the water better than a “No Swimming” sign would.
I recommend Chollas. Those things are hell. You step on them and it costs you a brand new pair of sneakers
g
I’m with George on that one, too. Cholla can pierce boot soles a sidewinder would just glance off of.
Plant ISIS flags in your yard (and stop paying $49 a month for a security system). Your yard will be watched 24 X 7 by local, state, and federal police.
Similar tactic to widowered seniors whose pensions were eliminated deliberately committing non-violent federal crimes to receive free retirement and healthcare in a minimum security federal prison.
Get on Google Earth and take a look at what percent of the ground surface in LA is irrigated lawn. With the roads, sidewalks, roofs, non-irrigated lawns, and tree canopy, there is probably less than 5% irrigated lawn cover. There appears to be far more irrigated lawn in the acres of golf courses and baseball fields than there is private irrigated lawns. I doubt it would make as much of a difference as the model shows.
Besides, what’s the real difference between 82 F with a dew point of 55 F and 85 F with a dew point of 50 F?
RWT,
Astroturf?
3 degrees F….. 🙂
Next up, drought-resistant golf courses? One huge bunker…
Sand course.
Several places in Australia have them.
The “greens” are just smoothed sand.
Deserts have a greater daytime to night time temperature fluctuation? Less evaporation might might mean less rain? Without water the Imperial Valley would not be productive agricultural land? Oh the humanity!
I think “Oh the humidity!” would be more appropriate.
At my house we had already noticed the night time drop in temperatures as we are actually doing more rock scape and fewer plantings. In our case the reason for switching is easy to figure. We are getting older and want to expend physical efforts in the Western outdoors elsewhere.
As far as the impact of higher daytime temperatures goes if an increase is followed by by a drop in relative humidity, the best thing to do for older people is add shade. Outdoor evaporative cooling and misters can lower temperatures amazingly and make being outside in 110 degree weather tolerable to pleasant.
I worked outside on the Yuma County, AZ, desert year round for 20 years before retirement. I always wore 100 percent cotton clothing with long sleeves and carried a spray bottle of water. Simply spraying down my clothes dropped my body temperature, sometimes making my clothes feel chilled against the skin at 115 degrees. Getting out of a lukewarm summer swimming pool here produces instant chill in the early evening.
This might be a good time to buy stock in one of the companies providing misting systems.
http://www.front-porch-ideas-and-more.com/outdoor-mister.html
Or sell the stock on the assumption misters will be banned.
Ernest says, and I stress,
“…and carried a spray bottle of water”
Even just moistening one’s shoulders when wearing a T-shirt can provide significant relief in dry/hot environments, I’ve found. Evaporation is your friend ; )
John Christy addressed this years ago.
http://journals.ametsoc.org/doi/full/10.1175/JCLI3627.1
Thanks to irrigation, and transpiration in plants, more plants result in warmer nights and less warm days, with an overall net warming. Fewer plants, and no irrigation, result in hotter days and cooler nights with a net cooling.
..That is why, in a desert, is it extremely hot during the day and very cold at night !
Exactly. Both cited studies, Christy and USC, may be recent news to many people, but the irrigation affect has been noticed by farmers/ranchers in these parts (NE Cal) for a couple of generations.
I enjoyed reading both studies, because they provide results that correspond with known scientific principles.
AM,
This gets back to a point I raised earlier. What role does agricultural irrigation, and the expansion of agriculture into arid and marginal semi-arid regions, play in the apparent warming of the land surface?
Has Pielke Sr’s work been forgotten already?
Heat waves may be worse, but daily living is easier and more economical when you can cool down a house with a swamp cooler during the day and open the windows at night.
Agreed.
..I always find it amazing that a state with 3,427 miles of Tidal Shoreline could possibly ever have a continuous drought…Desalination plants are a lot cheaper than destroying your economy and the airborne wildlife…It is a desert FFS..They should have built many during the last drought…Even the Romans knew how to effectively use Aqua ducts ….
Living in Silicon Valley, I see a few neighbors who have switched to desert vegetation. Also, a few who save even more water by switching to Astro-turf. But, the idea of 100% switching seems far-fetched. I suspect that the real-world inpact of a limited number of lawn conversions would be negligible.
Meanwhile, many grass lawns are brown, due to water restrictions. I wonder how under-watering lawns affects the temperature. It’s a bigger issue than switching to desert flora, because there are far more under-watered lawns.
Note that if everyone did switch to desert or Astro-turf, the city could probably get more daytime cooling by spraying lots of water into the air and letting it evaporate. Of course, nobody would do this, since the area has barely enough water for the current population.
I dislike the article, because it provides and excuse not to take steps to save water.
Huh? It describes some steps with which to save water!
“Living in Silicon Valley ….”
Do you mean the Santa Clara Valley? Idiot!
I noticed that people that live someplace described by political terms rather than physical are clueless about their environment.
I have lived in Santa Clara Valley when it resembled the writing of Jack London. As an adult I was stationed in the Bay Area, LA (actually Long Beach), San Diego (Point Loma).
It may be just a coincidence that a navy guy was there but I think it would it had something to with the Pacific Ocean.
Could it be the Pacific Ocean had major effect on the climate in those places?
Here is the interesting thing about places with mild climates. They do not cope very well with a few extreme days as well places where very hot and very cold are normal. It is not landscaping that makes things worse but idiots. Especially when the permeate our education system.
Geeze, what is the problem? Now they won’t have to “adjust” the temperature data as much in LA if folks start using more drought tolerant vegetation.
exactly…they keep proving UHI is a whole lot bigger than “adjustments”
Latitude: Indeed
I wonder what is the best way to save the planet, always the topic in CA.
You could run fossil fueled, of nuclear powered A/C full power to provide the required cooling.
OR you could invest some resources into a reservoir system and utilize evaporative cooling on a personal, local, and municipal scale. This seems like a very environmental way to cut energy consumption.
You can save the water, but it costs you energy to do so. Then the saved water just gets dumped into the ocean, anyway.
I have referred to this picture before, but this shows London in terms of heat and if you know the area or study a map a lot of features are well defined.
Dulwich and Sydenham Hill Golf Club is notable in that it is cooler than surrounding cricket pitches and Dulwich Park. It is just above the dark blue of Dulwich Woods 1/5 up from bottom centre (see map link below). The golf course will be watered. All the grass areas in all the London parks show up as hot as these are not watered and the sun has direct access to the dry ground. Also of note is the dark woods and river Thames are cooler than the lighter short grass which will turn yellow or white after a prolonged dry spell.
Here is the Google Map link showing Dulwich Woods
https://www.google.co.uk/maps/place/Upper+Sydenham,+London/@51.4306725,-0.0799428,2841m/data=!3m2!1e3!4b1!4m5!3m4!1s0x4876015ff6c4e289:0x62c2698e4e438bdf!8m2!3d51.43066!4d-0.071188
Thanks for further justification of my hobby — golf. Good to know I am defending the world from global warming, and yes, I usually walk vs. riding in a cart.
Heathrow is plainly visible as a more or less rectangular zone (and in contrast with the open space and ponds to its West). Surprisingly (at least to me) it seems the buildings define the foot print more than the runways, although perhaps what I’m seeing are the various car parks around the perimeter and the runways, buildings and runways simply bleed together.
…Back when I was still in High School in Northern Canada ( many, many moons ago ), my teacher had us do “thought” projects on whatever we thought would help the poor in Africa..(lots of ads on TV asking for money at that time)…I suck at writing essays or even putting my thoughts to words, so I decided I would use schematic diagrams to show my “Thought” project….The general idea was to dig a giant hole in the desert sand in the edge of the desert ( 400 ft. deep) and create a new inland sea (reservoir) by connecting it to the Ocean by pipelines…My logic at the time, was that the problem with a desert was that it lacked water.. I assumed that extreme evaporation would force pure water into the atmosphere, thus, creating rain clouds in whatever area the winds sent it to, thus increasing the amount of plants in the area. ( location location, location)…As a byproduct for today, this “thought” project would also lower the supposed sea level rise…by transferring the “excess” ocean water to the atmosphere..At the time I thought it made sense, …I got an F in that class for my effort !!
Maybe a real Geoengineering expert could make it work ?
By-product could be collecting salt.
I have this suspicion that the reason you got an “F” wasn’t because the teacher thought it wouldn’t work, but because wasn’t the kind of “solution” they were looking for. Not Politically Correct, in other words.
As Instapundit is fond of saying “Insufficient opportunities for graft.”
You were on the right track. It’s been thought of. The Qattara Depression in Egypt “has been studied for its potential to generate hydroelectricity.” (https://en.wikipedia.org/wiki/Qattara_Depression) Basic idea would be as you described. Since there would be water loss by evaporation, there would be a constant inflow of water from the Mediterranean Sea.
1.3 degrees? WE’RE GONNA DIE! WE’RE GONNA DIE!
So if I get this right, this policy could increase daily variation in temperatures by up to 9.4 def F.
Yeah right!
I grew up in a very dry climate without airconditioning. We would open the doors and windows at night and close everything up during the day. The high temperatures in July would be above a hundred for a week or two but the night time temperatures would be down in the sixties.
If the night time temperature is going down more than the day time temperature is going up, there is no need for the airconditioning to increase. Burt Rutan has demonstrated that, even in the Mojave, you can build a house that doesn’t need air conditioning.
Living in hot climates without air conditioning is possible (sometimes at least 110F during the day here); I haven’t used mine for year now, However, I’ve often noticed the surrounding houses all running air conditioners late at night (easily heard with my windows open) when outdoors has cooled to marvelous air. I don’t think many people even notice what goes on outside their walls.
Depends on how well your house can turn over the air at night. If your windows don’t face the night-time breezes, or another structure blocks them, then you need an attic fan. Open the windows, run the fan to push air up into the attic and out, drawing outside air in. Maybe thirty minutes, then you’re done.
Born in central Europe and living few years in California I can tell difference. What is making weather unpleasant is humidity. With dry air ~20% RH man can withstand temperatures up to 31C without problems. 43C in Death Valley (Or 43C in Egypt in desert) with 7-10% relative humidity sounds scary, but actually it is much better then 35C with 45% humidity in the summer in Europe. Together with hot nights, when temperatures are not dropping under 26C it is awful. You can have your window wide open, there is no exchange of air and hour or two after sunrise 4:00AM temperature is rocketing up.
Damned if you do and Damned if you don’t…
Grew up in Southern Arizona. Paved roads are hotter than H3ll. Lots of people put in gravel ‘lawns’ which are much hotter than the natural desert. Greasewood bushes cool things. People consider these to be ‘weeds’. Mesquite trees are great desert shade but people don’t like the huge oily seed pods, etc.
The natural desert floor isn’t anywhere near as hot and dry as rock/asphalt landscaping and then there are the hot roofs with shingles, etc. that are much hotter than natural landscaping!
And all this leads to hot cities caused by humans insisting on living in deserts.
Using subsurface drip irrigation systems can reduce water consumption of turf by 70 to 90 percent. It is not without its complications and it is more expensive than sprinklers, but if you really want turf and don’t have a lot of water, then it is a viable option.
Also, using wick irrigation for containers, trees and shrubs can substantially reduce water consumption and improve the health of the plants. The basic idea for both systems is to restrict water loss to transpiration.
Choosing drought tolerant trees and shrubs that shade the ground will keep the microclimate more comfortable. Use wick irrigation and water usage will be negligible.
I much prefer hot and dry to kind of hot and humid. High temperatures here have been 95 to 100, but the humidity has stayed at 10 percent or less (the downside is that when the humidity rises to 25 percent, it feels muggy). Lows have been upper 60’s to low 70’s. There is a lot of time to do outdoor activities before it gets too hot.
“reductions in irrigation associated with adopting drought-tolerant vegetation would cause temperature increases,”
So, humans have helped cool temperatures? Sounds like another reason to adjust temperatures higher in the next revision…