Now it's climate change to be killing the Joshua trees

Study based on fossil sloth dung found in desert caves and packrat middens

From the US Geological Survey, because doing mapping and boundary lines are sooo yesterday:

Uncertain Future for Joshua Trees Projected with Climate Change

FLAGSTAFF, Ariz. — Temperature increases resulting from climate change in the Southwest will likely eliminate Joshua trees from 90 percent of their current range in 60 to 90 years, according to a new study led by U.S. Geological Survey ecologist Ken Cole.

The research team used models of future climate, an analysis of the climatic tolerances of the species in its current range, and the fossil record to project the future distribution of Joshua trees. The study concludes that the species could be restricted to the northernmost portion of its current range as early as the end of this century. Additionally, the ability of Joshua trees to migrate via seed dispersal to more suitable climates may be severely limited.

“This is one of the most interesting research projects of my career,” said Ken Cole, a USGS ecologist and the study’s lead author. “It incorporated not only state-of-the-art climate models and modern ecology, but also documentary information found in fossils that are more than 20,000 years old.”

By using fossil sloth dung found in desert caves and packrat middens — basically, the garbage piles of aptly named packrats — scientists were able to reconstruct how Joshua trees responded to a sudden climate warming around 12,000 years ago that was similar to warming projections for this century.  Prior to its extinction around 13,000 years ago, the Shasta ground sloth favored Joshua trees as food, and its fossilized dung contained abundant remains of Joshua trees, including whole seeds and fruits. These fossil deposits, along with fossil leaves collected and stored by packrats, allowed scientists to determine the tree’s formerly broad range before the warming event.

The study concluded that the ability of Joshua trees to spread into suitable habitat following the prehistoric warming event around 12,000 years ago was limited by the extinction of large animals that had previously dispersed its seeds over large geographic areas, particularly the Shasta ground sloth. Today, Joshua tree seeds are dispersed by seed-caching rodents, such as squirrels and packrats, which cannot disperse seeds as far as large mammals. The limited ability of rodents to disperse Joshua tree seeds in combination with other factors would likely slow migration to only about 6 feet per year, not enough to keep pace with the warming climate, Cole and his colleagues concluded.

The Joshua tree, a giant North American yucca, occupies desert grasslands and shrublands of the Mojave Desert of California, Nevada, Arizona, and Utah; Joshua Tree National Park in California is named after this iconic species. The Joshua tree is known for its distinctive shape and height of up to 50 feet.

Results of the study, “Past and ongoing shifts in Joshua tree distribution support future modeled range contraction,” appear in a current edition of “Ecological Applications.” The research team included Kenneth L. Cole, U.S. Geological Survey; Kirsten Ironside, Northern Arizona University; Jon Eischeid, NOAA Earth Systems Research Laboratory; Gregg Garfin, University of Arizona; Phillip B. Duffy, Lawrence Livermore National Laboratory and University of California; and Chris Toney, USDA Forest Service.


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Frederick Michael

But the seeds could be dispersed by a new species of large mammal — man.

“The research team used models of future climate,……..” YAWN!

Jason Bair

I don’t see any decline in Joshua trees. They do quite well in blazing heat and bitter cold.
Biggest thing that kills them is too much water and being knocked over from strong winds.
Are they implying that there was a similar spike in temps before AGW?

Dave Wendt

Let me see if I’ve got this. It’s been fine in the Mojave Desert for 12000 years but now it’s doomed. Who could argue with that?

Jeff Carlson

gee, maybe their territory shrank during the Little Ice Age ? who knows ? certainly not this bunch of morons …

David S

Looks like this is the stuff they are referring to for the dramatic climate change 11700 years ago.
Not even Hansen has got our temperatures changing this much! Can anybody tell me how the climate changed so much then (if the ice cores are reliable, of course) without the demon CO2 to drive it?

Matthew Bergin

I always find it puzzling that a 0.7 degree temperature change that humans wouldn’t notice is supposed to kill all other life on this planet. The Joshua tree survives an 80 to 100 degree temperature shift from night to day on most days but don’t add an extra 0.7 degrees or its game over. I am insulted that these researchers think I am stupid enough to believe this crap.


I am quite apalled.
If the Joshua tree becomes extinct, then we will all be doomed.
Help – just what can we do to save ourselves?
/sarc off

jack morrow

Alas- the baloney from these types is astounding and seemingly never ending. I think a look at the funding will tell the tale as usual.

David L. Hagen

Aren’t we supposed to cheer for the “survival of the fittest” as the Joshua tree and the sloth are apparently following “Darwinian” evolution?!
Or is this an appeal to a higher law?
If so, which law, and is that appeal proper?

Matthew Bergin

Sorry on the previous post replace that 0.7 degrees with 1.12 degrees F

kadaka (KD Knoebel)

Study based on fossil sloth dung…
This is the point where I had to stop for a giggle break.


I’ve got a hotter model and I say those Joshua trees will be gone in 30 to 60 years! (Now, where do I sign up for the USGS and get unlimited funding for modeling??)


It’s interesting how as the “science is settled” short-term climate predictions are steadily being discredited, new studies/ statements are appearing that extend the time-scales way beyond any currently interested person’s ability to challenge.
It is of great comfort however to learn that “state-of-the-art climate models” were used in this case rather than the older sort, which are clearly no longer state-of-the-art.
Brace yourselves for a veritable pandemic of further such research.


There may be another explaination if, in fact, the Joshua Tree population has/is declining. Perhaps the Ground Sloth eating the seeds was an element of the life cycle of the Joshua Tree. It wouldn’t be the first time.
Similar to the Dodo and the Calvaria tree in Mautitius.
“Some biologists believe the dodos ate the tree’s fruit, and that the trip through the bird’s stomach helped prepare the seeds for germination. But now that their partner in life is gone, only a few calvaria survive.”


Oh great, now the fossil sloth dung proxy.
After that warming 12000 years ago, did they hide the decline?
Models models, I am not scared from these flimsy predictions.
Does anyone have the temperature trend data for the Mojave Desert or near the Joshua Tree National Park?
This is the usual WUWT way to put the first stake through the heart of this dung.

Doug in Seattle

This study is based on the premise that changes in climate at the end of the last ice age are comparable to what we can expect in the near future. That’s a pretty big assumption, which, as far as I am aware, can only be supported by models.
Even so, if the Joshua trees survived the transition from ice age to present, which they apparently did (otherwise why are they there now), then why would anyone assume they would suffer through another such change?
The author’s assumption is that fossil dung is evidence that now extinct giant sloths were the primary way of spreading seeds. From that I would have to assume (great word) that there are no Joshua trees left in the SW, and that this study was a product of an over developed imagination of some “geological” ecologists.


Please… make the bad men stop. My brain can’t take it anymore.

Computer models, assumptions, guesses, wild projections, complete disregard for previous changes … what do you know? There really is a consensus!


Noted moonbat Ken Cole is at it again. Nothing about this study makes any sense. I guess the team thinks everyone is either a brainwashed greeny or is completely ignorant of the real geo-history of the American SW!


Bob (Skeptical Redcoat)
Not just Models Bob, State-of-the-Art Models.

Willis Eschenbach

Call me a crazed mathematician, but isn’t there something wrong with this statement?

By using fossil sloth dung found in desert caves and packrat middens — basically, the garbage piles of aptly named packrats — scientists were able to reconstruct how Joshua trees responded to a sudden climate warming around 12,000 years ago that was similar to warming projections for this century. Prior to its extinction around 13,000 years ago, the Shasta ground sloth favored Joshua trees as food, and its fossilized dung contained abundant remains of Joshua trees, including whole seeds and fruits. These fossil deposits, along with fossil leaves collected and stored by packrats, allowed scientists to determine the tree’s formerly broad range before the warming event.

I mean, if ground sloths went extinct 13,000 years ago, how much can they tell us about climate warming 12,000 years ago?
Shows the dangers of “science by press release”, I guess. Anyone have a copy of the actual paper?
REPLY: I wondered how long it would be before somebody noticed that, good for you Willis. – A

Scarlet Pumpernickel

So what happened 6000 years ago when it was 4 degrees warmer? Did the Joshua trees survive?

Hu McCulloch

Squirrels and packrats only move 6′ per year? This would be incredibly slow for a snail!


So ground squirrels and pack rats only move 6 ft a year…
…and irritable climate syndrome will move faster than that
Is there nothing these scientists don’t know??
Seems they would be worried about all of those very slow squirrels and pack rats…………


My reactions:
(1) This is a bunch of fossil sloth dung.
(2) I don’t give a coprolite.

Scarlet Pumpernickel

PS looks like Ken Cole will not have a job in a few years time with science like this


You silly people, don’t you know that the giant ground sloths drove equally giant ATVs all over the desert, belching out CO2 and strewing Joshua tree seeds hither and yon? The silly creatures were the engineers of their own demise, bringing about the end of the ice age with their filthy emissions. All the ATV parts were scavenged for modern art sculptures by the pack rats.

Scarlet Pumpernickel

I think I worked it out, these must be the ghosts of the previous Joshua trees, when it was much warmer in the Minoan warming, the Holocene Climatic Optimum and Medieval Warming they all died.
The ones we see today are not real, they are just ghosts….


Matthew Bergin says:
“I always find it puzzling that a 0.7 degree temperature change that humans wouldn’t notice is supposed to kill all other life on this planet. The Joshua tree survives an 80 to 100 degree temperature shift from night to day on most days but don’t add an extra 0.7 degrees or its game over.”
What about the “tipping point” at 100.7 degrees?
/sarc off


And Joshua trees don’t look very yummy to me. The sloths probably all died of hunger. They should have eaten the pack rats instead; I hear they taste like chicken.

1. The Joshua trees,which apparently can’t survive a 1 or 2 degree F temperature increase, survived the greater warming 12,000 years ago.
2. The trees, which can’t survive without seed dispersal by large mammals like the giant sloth, somehow survived 13,000 years with nothing but little rodents, even before the great warming.
3. The trees, which apparently can’t survive the aforementioned 1-2 degree increase, somehow survive daily temperature changes of multiples of tens of degrees.
Clearly these trees cannot be the product of Darwinian evolution. Creation science is proven; we just attributed it to Jehovah, when it was actually Gaia.
And if those rodents can’t move any faster than 6 feet per year, I can solve the problem right now: I have an abundance of squirrels and chipmunks here that move like fuzzy lightning, which I’ll be pleased to donate for relocation to the Mojave.

James Sexton

This continuous drivel about the desert is monotonous. Has anyone noticed the contiguous United States hasn’t warmed in the last 15 years?
Annual 1996 – 2010 Trend = -0.01 degF / Decade
Last 15 for the West Region(includes the Mojave), Annual 1996 – 2010 Trend = -0.26 degF / Decade
Last 15 for the SW(includes Arizona and N.M.) Annual 1996 – 2010 Trend = -0.31 degF / Decade
Yes, very scary, I think the Joshua trees have cooling to worry about, not warming. Can’t these imbeciles do a study based on reality rather than a model?

Richard Keen

I’d think the below zero weather last month across much of Josh Tree’s habitat ( ) would have more effect on the survival of many of these plants. Perhaps they should do a survey of how many Joshuas died from the all-time record extreme unprecedented really cold weather to see what the effect of actually occurring cold is compared to predicted maybe-will-happen warmth.


Its Friday, the brain is burning out, so I can contribute nothing but a humorous observation – stitching together some descriptive gems from two WUWT commenters today. (one piece from Latitude in this post above – the other somewhere else today)
New description for AGW alarmists….”Carbophobes suffering from irritable climate syndrome.”

Doug Jones

Not only have these desert plants, as species, survived just fine, *individuals* have lasted for almost 12,000 years:


“fossil sloth dung”
It’s just not for breakfast anymore!

Tom T

I’m getting more than a bit fed up with people using unreliable climate models to make predictions of things 100 years from now and calling it science.


What killed the sloths? Can anyone name a species killed by climate change?


U.S. Geological Survey ecologist, when was this position invented? and why? would it have anything to do with government funding to promote AGW?


“climate change to be killing the Joshua trees”

mike sphar

Its quite simple really. Just tell the Joshua Trees to take the I40 NorthWest or the I15 East or 395 North and they’ll get around much easier and at a much faster rate than 6 feet a year!


So how about some real tests on the Yucca’s. Grow some in a suitable system where you can control the temperatures. Jack up the temperatures to what the models predict and see how the Yucca’s adapt. How hard can that be?

Pamela Gray

Apparently it has also become so yesterday to study a CURRENT plant species suffering from CURRENT warming!

Charlie Foxtrot

The problem, obviously, is that the rodents that we are using to disperse the seeds need to be replaced by faster rodents. What worked for the last 12,000 years is simply not good enough anymore.


“It incorporated not only state-of-the-art climate models…”
Let me guess: worse than we thought?

I thought that the biggest danger to trees like Joshua Trees or Bristlecone Pines are Climate Scientists themselves!

“On 6th August 1964, one of the greatest crimes against Nature was committed when the oldest living inhabitant on Earth was unwittingly killed. WPN-114, previously known to its affectionate admirers as Prometheus, was a bristlecone pine tree that, posthumously, was discovered to have been at least 5000 years old.
In the summer of 1964, Donald R. Currey, a graduate student in geography at the University of North Carolina, was undertaking dendrochronology investigations to establish climatic change patterns during the Little Ice Age – the period of cooling that occurred for approximately 400 years until the mid 1800s. Dendrochronology, the method of dating based on the analysis of patterns of tree-rings, can date the time at which tree rings were formed to the exact calendar year. So, to facilitate his investigations, Currey went in search of the oldest living trees.
In 1957, a grove of bristlecone pines in the White Mountains above California’s Mojave Dessert stunned the scientific world when they were discovered to be the world’s oldest living trees. But while the California Bristlecone Pines captured the media’s imagination, another grove of bristlecones in the Great Basin at Wheeler Peak in eastern Nevada, not far from the Utah border, had slipped under the radar of all but few. And it was Wheeler Peak’s colossal bristlecones that Donald R. Currey chose for his investigations.
Currey began taking core samples from several trees, and took particular interest in the 114th sample – “one of the larger living bristlecone pines” – which he labelled WPN-114. After several attempts, Currey’s 28-inch coring tool broke. Without it, he was unable to obtain the continuous series of overlapping cores necessary to determine weather patterns. He therefore decided to ask the United States Forest Service to fell WPN-114.
National Forest District Ranger Donald E. Cox received the request. He consulted his superior, Slim Hansen, who was stationed some 250 miles away and consequently asked Cox to look at the tree and report back. Cox declared the tree to be “very common” and is reported to have said, “no one would have walked more than a hundred yards to see it.” Hansen replied, “Cut ‘er down.”
Robert Jacobsen, superintendent of the Great Basin’s Lehman Caves, attempted to intervene and wrote that cutting the tree “would be a loss to the world.” And at least one Forest Service sawyer is known to have refused to participate in the felling on moral grounds. Nevertheless, the felling was scheduled for 6th August.
It took the whole of the day to cut down and section WPN-114. In the process of his subsequent investigations, Currey discovered that WPN-114 had been alive for at least 4,862 years.
He had killed the world’s oldest known non-clonal organism.”

Death of Prometheus
The cut stump of Prometheus
In 1963, Currey was a graduate student at the University of North Carolina at Chapel Hill. Under a fellowship from the National Science Foundation, Currey was studying the climate dynamics of the Little Ice Age using dendrochronology techniques.
Bristlecone pines in the White Mountains of California and elsewhere were discovered to be older than any species yet dated, and in 1963 Currey became aware of a Great Basin Bristlecone Pine population in the Snake Range and on Wheeler Peak in particular. At the time he visited the area, in the summer of 1964, he did not know that previous researchers had examined the area. Based on the size, growth rate and growth forms of some of the trees he became convinced that some very old specimens existed on the mountain and, using the scientific methods of the time, Currey began taking core samples to check. He found that some exceeded 3000 years in age, taking particular interest in a tree he designated WPN-114, the previously named Prometheus.
Currey was unable to obtain a continuous series of overlapping cores from WPN-114: he had tried at least four times with a 28 inch long borer, breaking two borers, but to no avail. He decided to ask for permission from the United States Forest Service to fell the tree. He was already acquainted with Forest Service officials at the nearby Lehman Caves National Monument (now a part of the much larger Great Basin National Park which includes the area Currey was working in), and made a request with Donald E. Cox, a district Forest Service ranger for permission to cut down the tree in order to examine the whole trunk in cross-section. Cox felt that the request was scientifically sound and, after convincing superiors that the particular tree was not a notable landmark, gained approval for felling it.
After securing permission, Cox informed Currey and assigned a Forest Service crew to join the young researcher and bring back the samples. The tree was cut and sectioned on August 6, 1964, and several pieces of the sections hauled out to be processed and analyzed, first by Currey, then by others in later years. To their surprise, the tree was not only old, but older than any other non-clonal organism ever known.
[edit] Aftermath
It took a few years for the information about the felling of Prometheus to reach the public, but once it did there was great controversy. Most criticism centered on the U.S. Forest Service’s decision to permit the tree to be cut. However, some critics questioned how the cutting of such an old tree was necessary given the topic Currey was studying. Since the Little Ice Age started no more than 600 years ago, many trees could presumably have provided the information he was after for that time period. However, in Currey’s original report (Currey, 1965) he refers to the Little Ice Age as encompassing the period from 2000 BC to the present, thus defining the Age over a much longer time period than is currently accepted. Whether this was the common sentiment at the time is not known. In the article, Currey indicates that he sectioned the tree as much from the question of whether the oldest bristlecones were necessarily confined to California’s White Mountains (as some dendrochronologists had been claiming) as from its usefulness in regard to studies of the Little Ice Age.
The incident led to a tighter restriction on the felling of old trees, the eventual creation of Great Basin National Park (now overseen by the National Park Service), and the decision to hide the exact location of Methuselah, the tree believed to be the current oldest. Currey personally took part in lobbying efforts to get Congress to designate the area a part of a national park.” –

Yikes. So many claims of doomsday, so little time to squash them all.


Reading about sloth dung fossils gave me my Mojave mojo back. Can’t wait for organically impregnated “Save the Joshua Tree” T-shirts to come out. Dirt bikers will love them.


This article had me very nervous that my first rule of biology papers and global warming was wrong. My rule states: Anything that is soft and cuddly, warm and fuzzy, tasty and nutritious, or generally useful and beneficial; will be reported as doomed by AGW climate change. Conversely, anything stinky, noxious, disease bearing, toxic, ugly, creepy, invasive, poisonous, or thorny will do quite well.
From the picture, I thought I was looking at a thorny plant. But, no thorns, its just thin long leaves and the plant is quite useful and beneficial. My rule stands.


I have had 4 Joshua Trees growing here in New England for the last 40 years. The seeds came from a tree above the snow line in Tehachapi Pass and take 4′ of snow and sub-zero temps through high 90’s in the summer. They are one tough species.
disclaimer: No Grant Money was spent for this long-term study. 🙂