Guest Post by Willis Eschenbach
“Out of passions grow opinions; mental sloth lets these rigidify into convictions”
Friedrich Nietzsche, 1844-1900
Anthony discussed the press release about the paper Past and ongoing shifts in Joshua tree distribution support future modeled range contraction. I didn’t have a copy so I wrote to the lead author, Kenneth Cole, to request one. He responded immediately and sent me a copy. My thanks to him, that’s science at its best. Other than the ritual obeisance to the climate models, the paper tells an interesting story about Joshua trees and the extinct Shasta ground sloths.
The Joshua “tree” is a cactus not a tree, it’s one one of the famous Yucca tribe of cacti spiny spiky things that aren’t cacti according to folks who know better than I do. Calling it a tree is merely the other cactus’s Yucca’s polite way to try to make it feel better about its funny appearance and desolate condition. It grows where almost nobody else can grow, in a very restricted climate range in the American Southwest. Not too hot, not too cold, not too much rain or too little rain, just right.
The fruit of the Joshua tree is a seed pod that was a favorite food of the Shasta ground sloth. The sloth appears to have been the only major seed dispersal mechanism for the Joshua tree. Which is hardly surprising, since other than pack rats and ground sloths, there’ve never been many herbivores hanging out where the Joshua tree grows. It’s way dry in that corner of the US.
The black stars in Figure 2 (from their paper) show the current location of Joshua trees, in and around the Mojave Desert in the hot Southwest.
Figure 2. The authors used rainfall and temperature maps to determine where Joshua trees might possibly grow, with green showing the most favorable climates. Map shows the lower parts of California (left) and Nevada (upper middle), along with a section of western Arizona.ORIGINAL CAPTION: … (A) Suitable climate model for Joshua tree created with mid 20th century (AD 1930 1969) PRISM mean precipitation variables and extreme mean monthly temperature events.
Now, to start with their map is interesting. I mean, the Joshua trees are certainly not growing extensively in what is the best part of the their range according to the authors. Unfortunately, much of the area they say is best for Joshua trees is on Nellis Air Force Base, so there’s no information for large areas. On the other hand, some areas with orange or even red (low probability) have a number of Joshua trees. However, nature is never as neat as we’d like it to be, and they’ve done well to generally outline the range by climate variables. And if it becomes desirable to plant Joshua trees, we know where they’ll likely grow.
Fifteen thousand years ago, in the days of the now-extinct Shasta ground sloth, the geological evidence from pack rat middens and sloth dung shows that the Joshua tree was much more widespread. However, humans happened upon the North American scene around that time, and converted all of the ground sloths into ground slothburgers and barbecued them. Which was bad news for the Joshua trees (not to mention the sloths), because no one else had much taste for Joshua tree seeds. As a result, the range of the Joshua tree is much reduced from its former glory.
The authors also show that the current range of the Joshua trees is further north, and at a higher elevation, than in the times of the ground sloth. During the last ice age the range of the Joshua tree extended across other areas that are now too hot or otherwise unsuitable to support them. As it warmed at the end of the ice age, the Joshua trees retreated (and advanced) to their current locations.
The problem is that without the ground sloths, the Joshua tree’s only seed dispersal mechanism is pack rats. The authors estimated the rate of spread from packrats at two metres per year. This seemed low to me, but is explained in the paper. The missing parts of the puzzle were a) unlike sloths, the packrats only carry the seeds a maximum of about forty metres or so to their homes, and b) the trees take twenty years to reach maturity and produce seeds. Result … 2 metres per year rate of spread. Always more to learn.
So far, so good. And if they’d quit there, it would have been an interesting paper. But no, they had to bring in the climate models. Now, climate models are notoriously bad at predicting precipitation (rain and snowfall). So they figured they’d pick the best of the bunch, viz:
Future downscaled GCM projections
To assess potential future changes in Joshua tree’s suitable climate space we compared future projections from several GCM’s for the late 21st century (2070 2099; ~2X CO2). Five individual models and one ensemble of 48 runs of 22 models based upon the A1B carbon emission scenario were obtained from the Program for Climate Model Diagnosis and Intercomparison (PCMDI; AR4) archive (available online). The five individual models used were: Hadley Center for Climate predic tion (Hadgem1), Max Planck Institute for Meteor ology (Mpi_echam5), CSIRO Atmospheric Research (Csiro_mk3), National Center for Atmospheric Research (Ncar_ccsm3), and Centre National de Recherches Météorologiques (Cnrm_cm3). They were selected because they represent a wide range of future moisture availability conditions for southwestern North America (Seager et al. 2007), and they all were ranked within the top half (of 22 models tested) for their ability to hindcast 20th century precipitation seasonality within the southwestern U.S. deserts (Garfin et al. 2010). These models, especially the Hadgem1 and Mpi_echam5, outperformed most models in replicating the 1950 to 1999 AD geographic distribution of average seasonal precipitation (Garfin et al. 2010).
Then, once they had what they figured were the best five models giving a “wide range” of rainfall results, they ran them and tried to figure where the Joshua trees might live in the future. The models gave differing results, so the authors defined a threshold for suitability (18%). If three of the five models said a particular gridcell would be above the 18% suitablity threshold for Joshua trees, they called it an “area of agreement for future suitable climate (AAFSC)”.
Then they show what those 5 models (and the 22 model ensemble) said would be suitable areas for Joshua trees in the years 2070-2099. Which all sounds vaguely reasonable until we look at their results in Figure 3 …
Figure 3. Results for five models (B-F) and 22 model ensemble (G). Pink areas with thin black outline show current range of the Joshua trees. ORIGINAL CAPTION: … (B G) The Joshua tree future suitable climate model runs for late 21st century (AD 2070 2099 AD): (B) Hadgem1, (C) Mpi_echam5, (D) Csiro_mk3, (E) Ncar_ccsm3, (F) Cnrm_cm3, and (G) Ensemble (44 runs of 22 GCMs).
See, if those results were mine, I’d throw up my hands and say “Not ready for prime time”. Those models are all over the map. They said they picked the models to “represent a wide range of future moisture availability conditions”, but I wasn’t expecting that huge a range. One model is “everything’s fine”, another is “they’re all gonna die!” That’s so wide as to be useless, and these are among the best models.
I don’t see any way that an average of those, or an “AAFSC” of those (area of agreement for future suitable climate), has any meaning at all. One of the models shows a wide area of hundreds of thousands of hectares where the Joshua tree could live, and another shows no suitable area at all.
Finally, once again we have the problem I have called “Models all the way down“. While the model results are interesting, they’ve skipped a big step. I want to see a map, just like the maps above showing possible future distributions of Joshua trees. But I want one showing how well the individual models (and the 22 model ensemble) did at hindcasting the current distribution of the Joshua trees.
I mean seriously – before showing us the model forecasts for 2070-2099 Joshua tree distributions, shouldn’t they show us the model hindcasts for the 1970-1999 Joshua tree distributions? It wouldn’t rescue the paper, but at least it might give some reason to think the selected models might be better than throwing darts at a map of the Mojave region.
Because without that, it’s just models disagreeing and quarreling with each other, all the way down …
w.
“I don’t see any way that an average of those, or an “AAFSC” of those (area of agreement for future suitable climate), has any meaning at all. ”
I never understood how averaging the outputs of nonlinear models makes any sense at all. You basically combine them into a more complex nonlinear model, but there’s no way you can say you improved some kind of quality. Maybe it’s so every bug in every model gets a chance to ruin the output.
Next, watch out for well meaning humans relocating all Joshua trees in a sad effort to save them, resulting in an extermination instead.
Small point (big point to botanists) – Yucca are no more cacti than other spiny pokey things that break the skin that grow in the desert. They are in entirely different Orders with completely different flower parts – you might just as well conflate humans with aardvarks… Great posting nonetheless!
Sorry Willis, but the Joshua tree is not a cactus. The Yucca tribe are not cacti. They are monocotyledons in the family Agavaceae (order: Liliales). A cactus is a dicotyledon in the family Cactaceae. Both are angiosperms (i.e., flowering plants). Both cacti and Joshua trees are adapted to dry conditions, and have independently evolved succulent (i.e water-storing) tissues.
Otherwise, great post! Keep up the good work.
You’ve published that painting of my dog and me without permission either of the artist, Carl Buell, or the owner, yours truly. Please remove it.
Also – not that facts seem to matter much here – Joshua trees are not even moderately closely related to cacti, much less being cacti.
[Reply: My sincere apologies for the picture, which was linked from google’s cache. I’ve removed it at your request. ~db stealey, mod.]
I remember reading a similarly interesting article that the main seed dispersal mechanism for the Osage Orange was the Imperial Mammoth. Apparently it’s been downhill for the Osage Orange since the demise of the Mammoth.
Also, the dissapearance of so many large Pliestocene mammels from North America is an interesting study in itself.
Well no wonder. No giant ground sloths no Joshua tree planting going on.
I was surprised though at how few places there are without any Joshua Trees. That is a first for me; a detailed map of where stuff ain’t.
Would come in handy when looking for something I have lost to ust have a detailed map of all the places where it isn’t.
Are Joshua Trees really cacti; I don’t think so. If they are “Yuccas which I would buy inot, then they are like the cabbage trees that grow in New Zealand; and I would think they belong to the Lily family rather than the Cacti.
Never planty any kind of Yucca or Joshua tree, even withoutGiant Ground Sloth assistance, anywhere near your house, and in particular don’t plant one near your gas meter.
I once rented a house in San jose, that had a Yucca/ersatz Joshua Tree, groing around the gas meter; and I do mean around. The incoming gas main to the house went right up through the tree, and the tree as it grew was pulling the gas pipe up out of the ground,.or trying to snap the gas meter off the top of it.
In any cvase, it is hazardous work trying to cut a Joshua tree/Yucca Lily from aorund your gas meter with a chain saw. Hey it is hazardous work cutting a Yucca with a chain saw, without either giant ground sloths or gas meters. The saw will jam in the pulpy wood of the tree, and kick back on you when you least expect it.
And I do own a house where some earlier owner planted Yucca/Joshua Lilies right up against the house, so they are in the process of turning the house over, aided and abetted by a giant Arecaria Pine from Patagonia, a three foot diameter trunk tree, that is a8 inches away from the house wall, and has its own semicircular encroachment on the eave of the house. When the wind blows, you can hear the tree trunk, banging up against the house.
Hey this house is so old, that it could easily have been Giant ground Sloths that planted the Yucca lilies. Is the Sego Plant a lily related to the Yucca/Joshua Tree ?
But I don’t think they are a cactus.
Gotta love those Klimate models.
Nice picture of Chris Clarke, Zeke and the giant ground sloth, painted by Carl Buell. Might be nice to add a credit line beneath it.
Somehow that a8 inches was supposed to come out at 18 inches.
Because without that, it’s just models disagreeing and quarreling with each other, all the way down …
What say they as to the number of Angels on the head of a pin? Just thought I’d ask since the Turtles have been so slow in responding.
I think the model results of this paper are absolutely perfect.
Without a doubt, they show exactly what we should be deriving from computer models applied to climate forecasting and impacts on global systems.
Namely, nothing.
Excellent point, Wills.
No model forecasting the future should ever be allowed to be published in a scientific journal unless it clearly demonstrates ability to “predict” the past.
Else a model is merely a highly expensive and worse than useless guess. An opinion, a passion, disguised as the “truth” for the gullibles.
Regards
Sanjeev
Willis, thanks as always for writing a post that’s not only educational but fun to read.
Ahh, the Joshua tree. Brings back memories of this midwestern boy’s first foray into the Mojave back in the early 70’s. I had never seen desert trees before and didn’t realize that the green “leaves” were actually very hard spikes. I approached the tree to partake of the shade underneath, only to run face first into one of these daggers they call leaves. The face bleeds quite profusely when punctured by a Joshua leaf. My mother still laughs at the memory, though she was quite concerned at the time.
The environmentalists would probably shoot me today if we tried many the fun things we did with motorcycles in the Antelope Valley back then. I still remember going full throttle up one of the buttes out there, coming to an unexpected peak with the trail going down and to the left, but straight ahead, like the goal posts on a football field stood a Joshua tree with no middle branches just ones to the left and right. Doing about 70 at a 45 degree incline and no time to do anything about it (12 year olds are stupid!), I jumped right through the open arms and landed in a group of tumbleweeds and continued on as though nothing happened. (I did learn a bit of wisdom though and took new trails at a reasonable pace afterwards!)
It is too bad about the seed dispersal problem. It does tend to shine another light on the popular myth of the Native American connection to all things living. Hunting a prey animal to extinction sure isn’t a very green thing to do. (I am part Indian [very small part] and have always thought Indians are just people too with the same foibles and strengths as any other.)
#
#
Dave Stephens says:
March 30, 2011 at 3:05 pm
Small point (big point to botanists) – Yucca are no more cacti than other spiny pokey things that break the skin that grow in the desert. They are in entirely different Orders with completely different flower parts – you might just as well conflate humans with aardvarks… Great posting nonetheless!
###
Aardvarks are way closer to humans then cacti are to agavae!
So it is like I So:ed the last time.
Climate change has nothing to do anything with them little cacti trees.
Essentially, they’ve survived 50 000 years, the loss of 50% of their seed carriers, the rise and fall of a whole ice age, and tens of thousands of tripping freaking hippies thru the ages (as has another more famous but slower growing cacti.)
Of course they might not survive the crazed climate communist hippie vegan crowd trying to dissect every veggie looking carbon dioxide to oxygen filter they happen upon, to feel sorry for, before they frigging devour it. Still that has nothing to do with climate change, lest, of course, one start to ponder the local climate of hippie under pants?
George E. Smith
March 30, 2011 at 3:33 pm
The sego palm is not even close to palms or any flowering plant for that matter! They represent true ancients. Google them, you will be facinated ( I hope).
Have just had the misfortune to visit Mr Chris Clarkes site (out of curiosity due to his complaint) and noted his out of hand dismissal of this site! Not good form in my humble opinion – but I guess us denialists are used to it!
But I would like to make a couple of observations (mods and Anthony permitting?)
Firstly, if a picture from google is ‘out there’ – shouldn’t his complaint be at least partly directed to them.
Secondly, wherever the image was found, was it properly credited/attributed and copyright claimed?
Thirdly, I am curious as to the reason for Mr Clarkes visit to this site – obviously a warmist, I can only presume he was ‘tipped off’?
And finally, with the deepest of respect – I can honestly say that the majority of folk I have read on this site are decent people – mostly in the quest for an honest science appraisal instead of politicized Bulldust. Of all the sites where an honest mistake can or could be made – this is the most likely – and I suggest that Mr Clarke would find it well worth reading.
The path to enlightenment is a long one, dear brother…….
Chris Clarke says:
March 30, 2011 at 3:14 pm
Done, with my apologies. Sorry I linked to your site, I was hoping to drive some traffic your way to benefit both you and your artist, but since you obviously don’t want that, it’s gone. Enjoy the silence. You could also mention to your artist that you prevented his work from getting wide public exposure on a non-profit site with a link to his original work. I’d prefer you tell him and not me, for the obvious reason.
I’m happy to remove the painting, and in fact one of the moderators beat me to it while I was writing this. That’s how we do it here. However, if you want to add childish insults, well, that loses you points rather than gaining them. It just makes you look petty despite the fact that you are right. And you were doing so well, too. In the future you might consider quitting while you’re ahead.
I have changed the cactus reference to avoid insulting the Joshua trees by thinking the cactus were related to them, perhaps you could apologize to them for me as well. You do understand that my whole riff on cactus was just humor, and had no real bearing on the paper?
w.
I have a picture of me and a dog that you’re welcome to use. Maybe Josh could whip up a sloth and a joshua tree, you could strip them all together for a nice replacement.
I’m sorry that Chris is upset about his likeness being used. I clicked on the source and saw it on that URL….and since he’s upset about people seeing it, I promise I won’t go there again or look at him.
To the point…species come, and species go. When they live in environments that are “perfect” to their evolution (egads! he used that word!), they’re living on the edge in the first place. How many other myriad species have come and gone because the climate that developed and they adapted to changed, and they didn’t un-adapt?
How do we know that these plants won’t simply adapt quite nicely?
As for hindcasting? You’re going to suggest using that to validate a model?? Heresy.
Hank Fox says:
March 30, 2011 at 3:35 pm
Before the picture was removed at Chris’s request, the picture had what’s called a “link” to Chris’s site which contained all of that and other information. If you pressed that little blue thingy with the line under it (the “link”) it would have taken you to Chris’s web site.
This was much better than a credit line, because it took you where you could actually find out about Chris and his dog and the Artist Currently Known as “Removed at Chris’s Request”.
All gone now.
w.
Well said and agreed Willis – one day, when I have accrued enough cash for a flight, I would like to fly across the Atlantic just to meet up and share some stories and experiences!
Good post anyways!
Most importantly, when will the Climate Modellers finally confront the ultimate question, “Who is going to feed the bed-bugs?”
Good article Willis as usual but I don’t believe any of their “studies” and I find it hard to believe any study about 13000 year old crap. I think maybe you don’t either but I guess I could be wrong . I think the study is sloth crap.