Here is just one more indication that despite what some would like you to believe, the MWP was not a regional “non event”.
From a University of Arizona press release,
Giant Sequoias Yield Longest Fire History from Tree Rings
California’s western Sierra Nevada had more frequent fires between 800 and 1300 than at any time in the past 3,000 years, according to a new study led by Thomas W. Swetnam, director of UA’s Laboratory of Tree-Ring Research.
A 3,000-year record from 52 of the world’s oldest trees shows that California’s western Sierra Nevada was droughty and often fiery from 800 to 1300, according to a new study led by University of Arizona researchers.
Scientists reconstructed the 3,000-year history of fire by dating fire scars on ancient giant sequoia trees, Sequoiadendron giganteum, in the Giant Forest of Sequoia National Park. Individual giant sequoias can live more than 3,000 years.
“It’s the longest tree-ring fire history in the world, and it’s from this amazing place with these amazing trees.” said lead author Thomas W. Swetnam of the UA. “This is an epic collection of tree rings.”
The new research extends Swetnam’s previous tree-ring fire history for giant sequoias another 1,000 years into the past. In addition, he and his colleagues used tree-ring records from other species of trees to reconstruct the region’s past climate.
The scientists found the years from 800 to 1300, known as the Medieval Warm Period, had the most frequent fires in the 3,000 years studied. Other research has found that the period from 800 to 1300 was warm and dry.
“What’s not so well known about the Medieval Warm Period is how warm it was in the western U.S.,” Swetnam said. “This is one line of evidence that it was very fiery on the western slopes of the Sierra Nevada – and there’s a very strong relationship between drought and fire.”
Droughts are typically both warm and dry, he added.
Knowing how giant sequoia trees responded to a 500-year warm spell in the past is important because scientists predict that climate change will probably subject the trees to such a warm, dry environment again, said Swetnam, a UA professor of dendrochronology and director of UA’s Laboratory of Tree-Ring Research.
During the Medieval Warm Period extensive fires burned through parts of the Giant Forest at intervals of about 3 to 10 years, he said. Any individual tree was probably in a fire about every 10 to 15 years.
The team also compared charcoal deposits in boggy meadows within the groves to the tree-ring fire history. The chronology of charcoal deposits closely matches the tree-ring chronology of fire scars.
The health of the giant sequoia forests seems to require those frequent, low-intensity fires, Swetnam said. He added that as the climate warms, carefully reintroducing low-intensity fires at frequencies similar to those of the Medieval Warm Period may be crucial for the survival of those magnificent forests, such as those in Sequoia and Kings Canyon National Parks.
Since 1860, human activity has greatly reduced the extent of fires. He and his colleagues commend the National Park Service for its recent work reintroducing fire into the giant sequoia groves.
The team’s report, “Multi-Millennial Fire History of the Giant Forest, Sequoia National Park, California, USA,” was published in the electronic journal Fire Ecology in February. A complete list of authors and funding sources is at the bottom of this story.
To study tree rings, researchers generally take a pencil-sized core from a tree. The oldest rings are those closest to the center of the tree. However, ancient giant sequoias can have trunks that are 30 feet in diameter – far too big to be sampled using even the longest coring tools, which are only three feet long.
To gather samples from the Giant Forest trees, the researchers were allowed to collect cross-sections of downed logs and standing dead trees, he said. It turned out to be a gargantuan undertaking that required many people and many field seasons.
“We were sampling with the largest chain saws we could find – a chain-saw bar of seven feet,” he said. “We were hauling these slabs of wood two meters on a side as far as two kilometers to the road. We were using wheeled litters – the emergency rescue equipment for people – and put a couple hundred pounds on them.”
To develop a separate chronology for past fires, co-authors R. Scott Anderson and Douglas J. Hallett looked for charcoal in sediment cores taken from meadows within the sequoia groves.
“We can compare the charcoal and tree-ring fire records. It confirms that the charcoal is a good indicator of past fires,” Swetnam said.
Such charcoal-based fire histories can extend much further into the past than most tree-ring-based fire histories, he said. The charcoal history of fire in the giant sequoia groves extends back more than 8,000 years.
Increasingly, researchers all over the world are using charcoal to reconstruct fire histories, Swetnam said. Many scientists are analyzing the global record of charcoal to study relationships between climate, fire and the resulting addition of carbon dioxide to the atmosphere.
Swetnam’s co-authors are Christopher H. Baisan and Ramzi Touchan of the University of Arizona; Anthony C. Caprio of Sequoia and Kings Canyon National Parks in Three Rivers, Calif.; Peter M. Brown of the Rocky Mountain Tree-Ring Research and Colorado State University in Fort Collins; R. Scott Anderson of Northern Arizona University in Flagstaff; and Douglas J. Hallett of the University of Calgary in Alberta, Canada.
The National Park Service, the U.S. Geological Survey, Mountain Home Demonstration State Forest and Calaveras Big Trees State Park provided funding.
h/t to Dr. Leif Svalgaard
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@Mike D: But if humans were setting fires for millennia, there should have been an equal number of tree ring damage before and after the MWP — and there wasn’t.
The lower graph that heads this piece seems to have absolutely nothing to do with the university press release.
The lower graph is labelled “Climatic Changes in Europe.” The tree ring study was done in the western Sierra Nevada, in the United States. How do you expect to convince even open-minded and receptive people (such as myself) when you do this kind of thing?
Moreover, the graphs are not properly sourced. “IPCC Hockey Stick,” reproduced from where? “Historical view,” measured how, reproduced from where?
Also the university press release makes no estimates whatsoever about the actual temperature during the medieval warm period, only that it was “warm and dry.”
You have more than enough evidence for skepticism without presenting this kind of sloppy, misleading material.
There is a tree in Yosemite called the fallen giant. About 20 years ago, I bought one of those wide view disposable cameras to use on trip to Yosemite. I took a picture of my wife standing next to the trunk of the Fallen Giant. The photo is roughly 3×8 wide. I sometimes take the album out and say to people, “my wife is in this photo. Can you find her?” Without exception, people are unable to locate her because they don’t comprehend the scale of the human vs the tree.
Doug Badgero,
You are correct about those knotty bristle-cone pines, I agree with everything you said, but unfortunately, some still use them as a temperature proxy and they happen to be one of the most divergent trees used.
Mike D. (18:55:01) :
Do forest fires ever start naturally?
I have heard of native Indians starting prairie fires. But not too much about forest fires.
Could you provide a link or a book title that shows that American Indians started forest fires?
Mike D. (18:55:01) :
And if American Indians did start forest fires why did they start more of them during the Medieval Warm Period, 800 to 1300, than at any other time?
Here’s a photo that approximates the one that I took of my wife, although mine was better (of course!)
http://htmlhelp.com/~liam/California/Yosemite/MariposaGrove/FallenMonarch1.jpg
The post by Mari Jensen is right on. There is much to be learned from these trees, as opposed to, say, Yamal as interpreted by Briffa.
Puzzling Graphs
This article was supposed to be about the findings of a study titled “Multi-Millennial Fire History of the Giant Forest, Sequoia National Park, California, USA. I was puzzled by the graphs at the beginning of the article, so I went to the study for clarification. But I did not find these graphs in the study.
savethesharks (18:10:40) :
I have 1/2 dozen of them growing in my yard. They love to be planted in soil that has been cooked by a hot fire. No fertilizer. Just Sun, C02, water and raw mineral soil. The tops of them follow the sun, bending up to 15 degrees.
Mike D.
“It is thought that 50,000,000 people lived in the Americas before 1492..”
I had an anthropology professor, 40 years ago, who asked just that question. But more specific to the size of the “Native American” population prior to the “white man” coming to America.
He got all sorts of answers, many in the multi millions. He then laid down the bomb: “Prior to the ‘white man’..coming to America, there NEVER was more than 500,000 in habitants in the whole of North America, and likewise in South America. That’s what we will prove this semester!”
He then went on TO prove it, by studying the “remains” of the ancient groups, and reviewing either their “hunter gatherer” life style or their LIMITED agriculture.
To claim that the sequoia’s, WITH NO TRACE OF MAN in the area going back 1500, 2000 years… were harmed by fires set by man is at BEST, ludicrous. At worse, a facicious, ficticious untruth.
Mike,
The authors are correct. Forestry service conservation practices altered the natural, low intensity burn offs that occurred in regularly over the centuries in the Sierra and elsewhere. The Forestry Service thought forest fires were to be fought and extinguished immediately. That practice allowed the unprecedented build up of tinder-dry fuel over decades. Forest fires became conflagrations and we lost more timber than we saved. It wasn’t until relatively recently that the Forest Service came to understand that nature’s way was the best way to conserve our forests.
I don’t know of any reason why the prehistoric hunter-gatherers who inhabited the western US would have started fires in the Sierra or other western forests, unlike their agriculturally-based slash and burn relatives in southern Mexico, Central and South America.
Ref – Mike D. (18:55:01) :
“Come on people now!!!!!!!
“Human beings have been living in the Sierras for 10,000+ years. It is well-known and well-documented that human beings everywhere and in CA, too, set fires to modify the landscape for survival purposes. I venture that EVERY fire scar Swetnam et al looked is from an anthropogenic fire!!!!”
________________________________
On this issue I think you may be a tinnsy winnsy wrong. Fires for clearing, yes. Accidental fires, yes. Fires in the grove of the Gods set deliberately to tick the “The Great Spirit” and his friends off and bring famine and disease to you and your tribe? No way Jose! The only people crazy and dumb enough to ever try something that stupid were born in the last 25 years and, fortunately, none of them have been successful -to date.
In other places in the world (eg the Sahara), regions of the world became warmer and wetter during the MWP. But in the American West, it became drier, which suggests that during warmer periods, La Nina predominates in the Pacific.
4 billion (18:27:31) :
The MWP was not warm the entire time.
Looking at the smoothed graph it would appear that it was. Do you know what smoothing is?
The raw data shows temps were up and down during those years.
But the data also shows the warm years were much warmer than warm years now in this two past decades—supposedly the warmest decades on the last 1000 years.
“Even less confidence can be placed in the original conclusions by Mann et al. (1999) that “the 1990s are likely the warmest decade, and 1998 the warmest year, in at least a millennium …””
————————
I believe that’s from the NRC report that the American Statistical Association discusses in a newsletter. The newsletter also had this to say about the NRC’s findings”
‘Despite all this evidence, the NRC report phrased its conclusions cautiously, concluding it was no more than “plausible” (2:1 odds in favor) that the temperatures of the last few decades were unprecedented in recorded history.’
http://www.amstat-online.org/sections/envr/ssenews/ENVR_9_1.pdf
Pascvaks (19:43:16) :
Clarification –
“Fires for clearing, yes.” But NOT in the Grove of The Giants! There’s not a whole lot of great sunlight for your pumpkins and squash.
Mike D
The Americas were not devoid of people when Columbus landed. Even he didn’t claim that. It is thought that ~50,000,000 humans lived in the Americas in 1492>>
Wow. Columbus landed in 1492 and did a population survey across a few million square miles of continent? How’d he do it? Stand in the crows nest at the top of the mast of one of his ships with a spyglass and count them? Not to mention that 50,000,000 people could not possibly feed themselves as a hunter gatherer society. Also not to mention that primitive tribes who lived off the land were skilled outdoorsmen which would include knowing how to control a campfire. If they weren’t skilled outdoorsman… well then they were dead.
“Droughts are typically both warm and dry, he added”
Is this what they call dry humour?
What is the accuracy range of dating tree rings this old? 1 yr? 10? 25? 50? 100? What?
I’m more and more wondering if the hockey stick disappeared the MWP in large part because of inaccurate dating of multiply proxies cancelling each other out.
Picture Gallery of Trees and Tree Rings (Univ. of Tenn., Knoxville)
http://web.utk.edu/~grissino/gallery.htm
Mike D. (18:55:01) :
~50,000,000 humans lived in the Americas in 1492. Many were in CA, and like people everywhere, they controlled the fire regimes.
I don’t think either one of these facts are correct, especially about ‘Many were in CA’.
Would you tell me the source?
Wren (19:34:00) :
Are you feeling ok Wren? Do you have a fever or anything?
Joe,
yes, global warming says this type of event can happen.
Unfortunately the Models that purportedly embody the physics that AGW is based upon are incapable of matching the Little ice Age, Medieval Warm Period, Roman Optimum, and all other extreme temp events in the past!!!
Now, saying something can happen in a certain way and SHOWING HOW it can happen in a certain way is the difference between gossips and scientists.
Max Hugoson (19:39:17) :
Max,
I had learned something similar, that the population of native Indians west of the Mississippi was ~250,000. Some of the tribes, apparently, had only about 400 people. And some small tribes were wiped completely out in warfare with other tribes. The population couldn’t have been in the millions.
I think Mike D. is just rambling some sarcasm.
Mike D. (18:55:01) :
“Human beings have been living in the Sierras for 10,000+ years. It is well-known and well-documented that human beings everywhere and in CA, too, set fires to modify the landscape for survival purposes. I venture that EVERY fire scar Swetnam et al looked is from an anthropogenic fire!!!!
This is a human-mediated, human-caused phenomenon being investigated. It has nothing, zero, nada to do with climate. That’s just backasswards.”
================================================
‘Every scar’ would be wrong as it is proven that lightning can produce forest fires, and this is a natural recurring phenomenon.
Also, your presumed conjecture that humans would be using fire to clear land in forests does not seem consistent with my understanding of how we used fire in the past to create farmland, our ancestors would have more likely set fire to fields.
And if it would be your assertion that fires set in fields would spread to forests…well, then wouldn’t the forests have to be dry and susceptible to lightning induced fires for this to occur? Can you imagine the difficulty in farming land with fallen trees, and with some trunks still extending to the heavens blocking sunlight?
“That’s just backasswards” – have to agree from my point of view.
You’re trolling, right?
davidmhoffer (19:54:41) :
Wow. Columbus landed in 1492 and did a population survey across a few million square miles of continent? How’d he do it? Stand in the crows nest at the top of the mast of one of his ships with a spyglass and count them?
………………………………………………………………………………………………………………
No, he didn’t actually get the real data. It was estimated, and homogenized, using a NASA grid model. That’s why the number is artificially high. He used a more heavily populated area to start with instead of those sparser forest and mountain areas. He just figured that it would all come out in the wash the same as if he used the real data.