15 Mar 2010: Report

What’s Killing the Great
Forests of the American West?

Across western North America, huge tracts of forest are dying off at an extraordinary rate, mostly because of outbreaks of insects. Scientists are now seeing such forest die-offs around the world and are linking them to changes in climate.  

by jim robbins

For many years, Diana Six, an entomologist at the University of Montana, planned her field season for the same two to three weeks in July. That’s when her quarry — tiny, black, mountain pine beetles — hatched from the tree they had just killed and swarmed to a new one to start their life cycle again.

Now, says Six, the field rules have changed. Instead of just two weeks, the beetles fly continually from May until October, attacking trees, burrowing in, and laying their eggs for half the year. And that’s not all. The beetles rarely attacked immature trees; now they do so all the time. What’s more, colder temperatures once kept the beetles away from high altitudes, yet now they swarm and kill trees on mountaintops. And in some high places where the beetles had a two-year life cycle because of cold temperatures, it’s decreased to one year.

Such shifts make it an exciting — and unsettling — time to be an entomologist. The growing swath of dead lodgepole and ponderosa pine forest is a grim omen, leaving Six — and many other scientists and residents in the West — concerned that as the climate continues to warm, these destructive changes will intensify.

Pine Beetle Damage
Photo by iStock
Scientists say massive forest die-offs from tree-killing pests are a symptom of a larger problem: warming temperatures and increased stress caused by climate change.
“A couple of degrees warmer could create multiple generations a year,” she said, as she chopped off a piece of bark on a dead lodgepole pine to show the galleries of burrowing larvae. “If that happens, I expect it would be a disaster for all of our pine populations.”

Across western North America, from Mexico to Alaska, forest die-off is occurring on an extraordinary scale, unprecedented in at least the last century-and-a-half — and perhaps much longer. All told, the Rocky Mountains in Canada and the United States have seen nearly 70,000 square miles of forest — an area the size of Washington state — die since 2000. For the most part, this massive die-off is being caused by outbreaks of tree-killing insects, from the ips beetle in the Southwest that has killed pinyon pine, to the spruce beetle, fir beetle, and the major pest — the mountain pine beetle — that has hammered forests in the north.

These large-scale forest deaths from beetle infestations are likely a symptom of a bigger problem, according to scientists: warming temperatures and increased stress, due to a changing climate. Although western North America has been hardest hit by insect infestations, sizeable areas of forest in Australia, Russia, France, and other countries have experienced die-offs, most of which appears to have been caused by drought, high temperatures, or both.

One recent study collected reports of large-scale forest mortality from around the world. Often, forest death is patchy, and research is difficult because of the large areas involved. But the paper, recently published in Forest Ecology and Management, reported that in a 20,000-square-mile
Dead forests now carpet the mountains and have transformed life in many parts of the Rockies.
savanna in Australia, nearly a third of the trees were dead. In Russia, there was significant die-off within 9,400 square miles of forest. Much of Siberia has warmed by several degrees Fahrenheit in the past half-century, and hot, dry conditions have led to extreme wildfire seasons in eight of the last 10 years. Russian researchers also are concerned that warmer, dryer conditions will lead to increased outbreaks of the Siberian moth, which can destroy large swaths of Russia’s boreal forest.

While people in some places have the luxury to doubt whether climate change is real, it’s harder to be a doubter in the Rocky Mountains. Glaciers in Glacier National Park and elsewhere are shrinking, winters are warmer and shorter, and the intensity of forest fires is increasing. But the most obvious sign is the red and dead forests that carpet the hills and mountains. They have transformed life in many parts of the Rockies.

It has hit home for me on a personal level. Virtually every one of the hundreds of old-growth ponderosa pines on the 15 acres of land where I live near Helena, Montana is dead, and we are surrounded by a valley of dead and dying forest. Most trees have been logged and taken to a pulp mill, where they were turned into cardboard for boxes.

Pine Beetle Damage
Photo by iStock
The tiny mountain pine beetle, which is just a quarter of an inch long, has destroyed nearly 70,000 square miles of forest in the Rocky Mountains.
University of Montana ecologist Steve Running says warmer temperatures in the Rockies bring spring earlier and fall later, each by about a week, yet precipitation has remained about the same. That translates into a drought, and stressed trees are highly susceptible to beetle infestations. Wintertime minimum temperatures in the 1950s, meanwhile, ranged from 40 F to 50 F below zero. That’s risen to the 30-below range, and there are fewer days when minimums are reached. It’s not getting cold enough anymore to kill the beetles, which over-winter in their larval stage and survive the milder temperatures because they are filled with glycol, a natural anti-freeze.

In addition, the past suppression of fire and the fact that many Western trees are reaching the age at which beetles target them — 80 to 100 years — are also factors in the widespread loss of forests.

So the forests across the West are dying, in such large numbers that U.S. Secretary of the Interior Ken Salazar called it the West’s Hurricane Katrina. In Colorado and southern Wyoming, the U.S. Forest Service has created an emergency management team to cut down dead trees around towns and along roads and power lines. Forest Service campgrounds and trails have been closed because of the hazard from dead trees, and communities surrounded by dead forests have drawn up emergency evacuation plans for residents.

Large-scale die-offs have occurred in the past. Mountain pine beetles are native to the West and are part of the ecosystem. Lodgepole forests regenerate through large-scale “stand replacing events,” which include fire and insects. The die-offs now, though, are on a scale unprecedented since
Interior Secretary Ken Salazar has called it the West’s Hurricane Katrina.
the West was settled and are so big that they are having unusual impacts on ecosystems. Diana Six contends that the whitebark pine, once largely protected from the beetles because it grew at high altitudes and was shielded by cold, is nearing functional extinction in large portions of its range and may no longer be able to feed grizzly bears and other species that love its high-fat nut. In Mexico, bark beetles are beginning to kill oyamel fir trees in a rare 139,000-acre biosphere preserve where the majority of North America’s monarch butterflies travel each fall to spend the winter. So far, about 100 acres in a core area of 33,000 acres have been killed by bark beetles.

Tree-killing bugs aren’t the only problem. In 2005 Colorado researchers noticed that aspens were suddenly dying in large numbers. That year they found 30,000 acres of dead aspen forest. The next year there were 150,000 acres, and in 2008 it had soared to 553,000. The die-off is called Sudden Aspen Death, or SAD. “It’s growing at an exponential rate,” said Wayne Shepperd, who researches aspen for the Forest Service. “It’s pretty sobering when you see a whole mountainside or whole drainage of aspen forest dead.”

Groves at low elevations and facing south are dying fastest, and scientists believe the cause is hotter temperatures and drier weather. It’s not only killing mature trees, but the root mass as well. An aspen grove is the offspring of a large single underground clonal mass, which sends up shoots. “The whole organism is disappearing and it has profound implications,” Shepperd said. “When the roots die, groves that are hundreds or thousands of years old aren’t going to be there anymore.”

If the die-offs continue, the loss of the aspen trees would be a blow to goshawks, songbirds, and a number of other species that find food and refuge in the groves.

Perhaps more than anyone, Craig Allen is familiar with these large-scale forest die-offs. A forest ecologist with the U.S. Geological Survey’s Jemez
There isn’t enough data to draw a conclusion about the reasons for forest die-offs globally.
Mountain Field Station in New Mexico, not only are his office and home surrounded by a pinyon die-off, he also is the lead author of the paper — with 19 other authors —published in Forest Ecology and Management, which sought to document and begin to understand what is happening to forests in North America and around the world as the result of climate change.

Coming up with a definitive understanding at this point is impossible, Allen says. Forests are complex, and unfortunately, woefully understudied, and there isn’t nearly enough data to draw a conclusion about the reasons behind forest die-offs globally. “There’s huge information gaps and uncertainties,” says Allen.

What contributors were able to do in the paper is collect anecdotal reports of broad-scale forest mortality from around the world. “The point of this paper is to connect the dots, at least the ones we can connect,” says Allen. “We can’t even tell you for sure if there’s more forest mortality. There’s not consistent monitoring.”

In 2005 a strong El Nino caused a dramatic drought in the Amazon. It killed forest across the region and is extremely well documented because so many researchers had existing plots there. “The heart of the biggest rainforest in the world turned from a carbon sink to a carbon source,” said Allen. “If you have long-term drought you can bleed a lot carbon into the atmosphere.”

A lot of beetles can also turn vast tracks of forest from carbon sinks to carbon sources. Take British Columbia, which is ground zero for the mountain pine beetle infestation in North America. Some 53,000 square miles of mature pine forest is dead and the province is projected to lose 80 percent of its mature lodgepole pine trees by 2013. The second largest known die-off there occurred in the 1980s and claimed just 2,300 square miles. Bill Wilson — the province’s director of Industry, Trade and Economics Research — said he has flown in a plane for hours over the province and seen nothing but dead forest the entire time.

In 2008, so much of British Columbia’s forests had died they also went from being a net carbon sink to carbon source.

Diana Six works in Africa where she has seen other die-offs first-hand. “In Africa where I work, suddenly whole hillsides are dropping dead,” she said. “It’s happening so fast people are in shock. It’s a tragedy.” Species include the quiver tree, camel-thorn, and the giant euphorbia, a 30-foot-tall succulent. The causes are not known, but the suspects are hotter and drier weather, or shifting rainfall patterns.


Arctic Tundra is Being Lost
As Far North Quickly Warms

Arctic Tundra
The treeless ecosystem of mosses, lichens, and berry plants is giving way to shrub land and boreal forest. As scientists study the transformation, they are discovering that major warming-related events, including fires and the collapse of slopes due to melting permafrost, are leading to the loss of tundra in the Arctic.
All told, the paper that Allen co-authored describes 88 well-documented forest die-offs around the world, going back as far as the 1960s and 1970s, although most are in the 1990s and 2000s.

If there was a way to predict die-offs, Allen said, land managers could take preemptive action, such as mechanical thinning or prescribed burning to increase the vigor of forests.

What gives researchers pause is that many of these large die-offs have occurred with minimal warming, in just a few years. In the West, for example, the average temperature has warmed on average 1.8 F over the past century. “This is before we put two to four degrees centigrade (3.6 F to 7.2 F) into the system,” said Allen, referring to forecasts for warming by the end of this century. Trees across the world are stressed already from fragmentation, air pollution, and other problems, he said. “I don’t know how much stress the forests of the world can take,” said Allen.

Correction, March 18, 2010: An earlier version of this article misstated the projected damage to British Columbia’s forests from infestations of mountain pine beetles. The insect outbreak is projected to kill 80 percent of the province’s mature lodgepole pine trees by 2013.

POSTED ON 15 Mar 2010 IN Biodiversity Business & Innovation Climate Energy Forests Policy & Politics Asia Europe North America North America 


Kudos on the thorough coverage of an issue that is largely out sight and out of mind to many Americans. The question now becomes, how do we manage these systems for resilience in the face of unprecedented environmental stress and global change? If anyone has a blanket solution, then there might be a Nobel prize committee interested in your work...

Posted by Nate Hough-Snee on 15 Mar 2010

Is there an areal or satellite photograph of the vast destruction available anywhere?

For instance of the the dead B.C. forests?

I read a comment at climateprogress that such a photograph is hard to find.

Such a horrific sight might wake some people up.

Posted by mark freed on 16 Mar 2010

"Large-scale die-offs have occurred in the past...since the West was settled."

"While people in some places have the luxury to doubt whether climate change is real..." Nice straw man argument. Overall a great article. Few, in fact, "doubt" climate change. It is a fact of life, just as the ice ages, interglacial periods, vast inlands seas and savannas of the past illustrate. The rub comes when science is falsified and unsubstantiated claims are made that are primarily driven by politics. The climate will continue to change dramatically in spite of any anemic attempts to do otherwise.

Posted by coyote_song on 16 Mar 2010

Thanks for an interesting article that does a great job at pulling lines of evidence together. Can you please provide the full reference for the recent paper in Forest Ecology and Management that is referred to?

Posted by Susan Solomon on 17 Mar 2010

The article states:

"In addition, the past suppression of fire and the fact that many Western trees are reaching the age at which beetles target them — 80 to 100 years — are also factors in the widespread loss of forests."

We need to reintroduce fire back into the system and evaluate how nature takes care of issues.

Posted by Jeff Flowers on 17 Mar 2010

In Maryland, where I live, the Emerald Borer is wreaking havoc on native forests. The authorities are pleading with people to STOP transporting firewood (for campsites, etc.) in order to slow the spread.

Is insect infestation more likely to be caused by weather patterns or human transport? From what I've seen of invasive species around the world, you don't need an environmental change to wipe out an old-growth forest--any new parasite or other infestation will have a massive impact.

A lot of this has been discussed as part of chaos theory, which deals with population ecologies.

Posted by Scott W. Somerville on 17 Mar 2010

"Can you please provide the full reference for the recent paper in Forest Ecology and Management that is referred to?"

Have a look here:


Posted by Sequoia on 17 Mar 2010

We had major problems with die back in our eucalypt forrests[Australia] a few years back. Most blamed the overpopulation of 'christmas beetles" for the decimation, and the fact that the possums were eating all the new growth. But being a natural ,cyclical phenomenon, our forrests are just the same as ever,though a lot greener recently due to long overdue heavy rains and flooding. But if enough people start to worry about the catastrophic loss of forrests,maybe Jim Robbins will do OK out of his "Forgotten Forrest". Please , dont panic, and enjoy whats left of the current interglacial.

Posted by ian hilliar on 18 Mar 2010

It's all too easy to place all the blame for our dead forests on "climate change". Nowhere is anyone talking about how tree densities are radically higher than before the Europeans arrived. No one is talking about the changes in species composition that favors bark beetles and catastrophic wildfires. The invasion of lodgepole pines into forests once dominated by ponderosa pines will result in losing those drought-tolerant and fire resistant pines that can live for many centuries.

Indians managed their forests through droughts and were experts at shaping them with "prescribed" fires. Why can't we manage our western forests, instead of the gridlock we are seeing today. Where is the "Precautionary Principle" when we are already seeing massive die-offs? Basically, eco-groups would like you to think that dying forests and massive firestorms are "natural and beneficial". There is a big push on to convince Americans that "fire needs to be re-introduced". The fires never left, but were suppressed. The government's Let-Burn program of letting wildfires reduce fuels is illegal, dangerous and VERY costly, both ecologically and economically.

Posted by Fotoware on 18 Mar 2010

The forests aren't dying. They are being renewed in a way that only Mother Nature/God has the full rationale for. The pine beetles kill the mature trees but are simply unable to destroy all the immature, and seedlings, and seeds. Mr. Robbins should go out to the woods this spring and have a look. He will see all the little pines are already well on their journey to being big pines.

In the areas where it is getting drier and the forests are indeed retreating, it is only part of a cycle that has continued since the last glaciation. Forest encroachment has indeed been occurring all through the American and Canadian west with the cool temperatures that ran from 1940 through to the end of the 80's.

The current natural "die back" of these trees due to warmer temperatures and beetles leads to the enhancement of a whole "range" of other values such as forage for wildlife and even grass for those dastardly bovines.

I hail from the epicentre of the mountain pine beetle epidemic in British Columbia and can assure you all will be well in the American west as the pine beetle makes it's cyclical epidemic run through the forest. (Mark Freed - no worries eh? there's no "dead BC forests"; they are just temporarily altered)

Posted by dbleader61 on 18 Mar 2010

This is a topical and timely article describing the catastrophic forest die-offs that are occurring in parts of western North America. However, in a few instances Robbins steps dangerously close to the line where sensationalism obscures science. For example, describing whitebark pine as "functionally extinct" is a major and likely premature claim for the wide-ranging and poorly-inventoried species. Also, 80 percent of British Columbia's mature lodgepole pines are projected to be dead by 2013, not 80 percent of its mature trees in general. I'm sure Robbins was intending no deceit when he wrote these statements, but they are the types of sentences that dissenters use as evidence that scientists bend facts to forward their own agendas, a la recent IPCC scandal. Using factually-impervious language in a compelling and persuasive manner gets the same points across, while avoiding potentially destructive backlash.

Posted by Sierra Curtis-McLane on 18 Mar 2010

"If there was a way to predict die-offs, Allen said, land managers could take preemptive action, such as mechanical thinning or prescribed burning to increase the vigor of forests."

The insect infestations and megafires are predictable and have been predicted by foresters for decades. They are also preventable through restoration forestry: returning forests to the densities of pre-Columbian eras and reintroducing controlled, anthropogenic fires.

Better to adapt and to impart resiliency and forest health than to wring hands and decry an unnecessary and undesirable fate.

Posted by Mike D. on 18 Mar 2010

I'm catching a whiff of anti-science know-it-all-ism from some of the previous commenters, especially those who make the unsubstantiated claim that recent large-scale die-offs due to insects and crown fires are entirely the result of past mismanagement (the latter may play a role). All one needs to do is read the articles in the special issue of Forest Ecol. and Mgmt. referenced in the YE360 piece (which after all is all about the effect of Climate Change on forests!). To wit, from Liu et al.: "future wildfire potential increases significantly in the United States, South America, central Asia, southern Europe, southern Africa, and Australia..."

The fact is, in the northern Rockies, thinned stands, indeed even lone trees miles from the nearest lodgepole stand, have been killed with equal likelihood by the beetle outbreak.

Very recently, studies have concluded, counter-intuitively, that past fire suppression played no role in the severity or frequency of chaparral fires. I think the jury's still out on whether fire suppression or climate change plays the larger role in severity and extent of recent coniferous forest fires.

Posted by Brad on 19 Mar 2010

The science of our dying forests is simple. The permutations of that science are endless. There are simply too many trees for the amount of annual rainfall. And, that includes climate cycles, as some individuals can live for many centuries. A complexity of external factors then enter into this example of a mass dieoff.

A tree's natural defense against bark beetles is to push the newly-laid eggs back out, using tree sap. When a tree cannot extract anymore water out of the ground in a radically-overgrown stand, it is wide open to deadly bark beetle attacks. When entire stands, and even entire watersheds, are so overgrown, all the trees become stressed and make perfect bark beetle habitat (which the eco's vigorously defend).

Sorry but, the science says heavy fuels increase the environmental damage in wildfires. It's not an either/or situation here, and the complex factors that affect forest health are cumulative upon the forest ecosystems. An intense wildfire over here destroys salmon spawning grounds way over there. Hydrophobic soils way up there causes flooding and erosion way down in the valley.

If we could magically "fix" our climate tomorrow, our forests would still be dying in vast numbers, partly because of overcrowding and species composition. Until those items are addressed, we will continue to see bark beetles and firestorms.

Posted by Fotoware on 19 Mar 2010

Dear Jim Robbins,

There is a very significant story here that remains largely untold. Ozone weakens trees and encourages insects, disease and fungus to finish them off. This is fact that has been demonstrated in peer-reviewed science, and yet the existential threat that is implicated seems to have made the subject taboo.

I wrote to Craig Allen and he refused to even consider ozone as a factor, even though beetles and warming only explain some of the declines in the west - not Sudden Aspen Decline, or Sudden Oak Death, or the shrinking of the biomass in Sequoia forests. Not to mention that trees are dying at a monumentally accelerating rate up and down the east coast.

Nothing would please me more at this point than for a reporter of your caliber to take on this challenging topic and put it front and center before the damage to annual foliage is so rampant as well that we have massive crop failures and famine.

Posted by Gail on 23 Mar 2010

Providing anecdotal evidence of forest die-offs is bizarre to me. The statement that periodic forest die-offs are common but then to assert they are occurring more often or more severely without any evidence to back them up is disturbing. I can't believe the low level science has reached that people of "science" make such anecdotal type claims as "proof." The fact that one researcher documents forest die-offs and notices more in the 1990s and 2000s may simply be an observational artifact.

We have a lot more memory and data recently than in the past. We'd expect there to be more known events than in the past simply because of poor record keeping in the past. Such is the case with things like hurricanes where we have only gotten satellites since 1979 to record EVERY storm that ever gets started so looking at data of storm frequency the number of storms jumps as our instrumentation gets better, just as the number of cases of cancer gets better as our diagnosis means improves. Getting good science is hard and the author of this article blithely seems to ignore all the articles prior to his which have been proven wrong because of poor attribution or not considering the larger picture.

Forest die-off is a good example of this ignore the larger picture. Forestation of the world has climbed dramatically over the last 3 or 4 decades. Satellites in orbit since 1980s show that overall green life has increased 20% on earth in just that short time. Life likes warmth and the fact that some forest might die here or there ignores the overall larger picture that life on the planet earth is exploding and growing. This is proven that overall forests are more plentiful than in many hundreds of years. The question about diversity remains open in my opinion. I have not seen definitive studies that consider all life at all levels and whether there is overall fewer species or more. What we know is that warmer planet can support more life and more diversity. Previous studies seem to show that diversity decreases during cold periods and increases during warm periods so it is counter intuitive to imagine that life is either diminishing overall or diversity is diminishing.

We need to understand if this author believes or has evidence that overall tree population worldwide is on a decline. It seems extremely unlikely given satellite data and the well documented evidence that CO2 is a plant food that increases plant size and growth and that high CO2 makes plants MORE resilient to drought. This is the principal reason as cited in Nature just 3 months ago or so that tree ring data since 1960 has been a poor predictor of temperature and is chopped off in computer models of the planets temperature.

Posted by john on 26 Mar 2010

I bought "The Dying of the Trees," by Charles E. Little, in 1995. It reviewed evidence across the USA of increasing tree mortality rates, and identified the predominant stressors in each area of die-back. Hence, I am not surprised to learn that this update bears more bad news, after fifteen years of political obfuscation as exemplified by "john's" March 26 comment above.

Posted by Nigel Strafford on 12 Apr 2010

All i heard from this article was the climate change is weakening the trees and the beetles are then able to kill huge sections of our forest. they then gave examples of forests all over the world that this is also happening. High temp and higher levels of CO2 make trees grow better. Drought can cause them to weaken but this wont allow beetles to boor into the cracks of the bark.

Posted by Joseph on 04 May 2010

I really appreciated how the article brought forward all the issues about how forests are in trouble. I think it is a good thing that these issues are being brought forward because they are real. All the evidence was there and was very reliable and useful.

Even though the main subject of the article is the problem of struggling forests, the article or scientists in general need to focus more on the forests that are thriving. In the article, Craig Allen says, "There’s huge information gaps and uncertainties." Based on my knowledge of ecology and my use of logic, to understand better why these forests are dying off, we need to look at the forests that are thriving. More specifically, we should study forests that can adaquitely sustain life, adapt, have a healthy balance of species and have a stable ecosystem. We can compare forsests that are dying and similar forests that are thriving. By studying the thriving ones we can compare and infer why the other forests are dying off. We can figure out why some forests are being effected by things like the beetles and other forests are not. -Jennifer W.

Posted by Jennifer on 16 May 2010

"Instead of just two Weeks, the beetles fly continually from May until October, attacking trees, burrowing in, and laying their eggs for half the year." I believe this article hits the spot on the overall damage the pine beetles do. My younger brother for Lego Robotics did a research piece, I think it was two years ago, on the pine beetles. I had no idea how much damage pine beetles where causing the forests. They manifest and take over entire forests and the damage is seen here in Colorado. "The Rocky Mountains in Canada and the United States have seen nearly 70,000 square miles of forest — an area the size of Washington state — die since 2000. For the most part, this massive die-off is being caused by outbreaks of tree-killing insects, from the ips beetle in the Southwest that has killed pinyon pine, to the spruce beetle, fir beetle, and the major pest — the mountain pine beetle — that has hammered forests in the north." This is completely true. I think its widely assumed that forest fires kill the majority of trees, but pine beetles wipe out millions. CSU has a great informational article on the Pine Beetles here's the link http://www.ext.colostate.edu/pubs/insect/05528.html.

As I agree with the overall effect of the pine beetles, I disagree with the fact that climate is effecting the population of pine beetles. The document expresses many different places where pine beetles are effecting the forests, but only one or two examples that even suggest temperature is a problem. I also believe since they state the fact that it's not cold enough anymore, they need to say what is the maximum temperature that causes pine beetles to die because of the temperature. "In the West, for example, the average temperature has warmed on average 1.8 F over the past century." So a 1.8 degree temperature increase is going to allow for more pine beetles? This fact doesn't exactly prove any point unless that 1.8 degree change made the difference, but they don't even state that fact. Another lacking of this paper is the intentional fact that there is global warming. I'm yet to choose a side of this, but this article definitely has that bias.

This article could have a better proven point had the research been there. In fact, had there been more straight on research I would have believed it. Until there is enough research to back up there claims I'm going to have to agree with the fact that, "Forests are complex, and unfortunately, woefully understudied, and there isn’t nearly enough data to draw a conclusion about the reasons behind forest die-offs globally. “There’s huge information gaps and uncertainties,” says Allen."

By explanation for the dying of trees, which was mentioned once in the article, is the suppression of the forest fires. As part of an ecosystems life, something has to wipe out the entire ecosystem to allow it to rebuild making it healthier. The majority of forest fires have been stopped causing the pine beetle to increase to wipe out the trees. The problem with the pine beetle is they wipe out the forest and don't allow for re-growth. This kills all of the ecosystem. They leave a blue fungus which infects the tree allowing no re-growth. When one pine beetle infects a tree there is nothing we can do.

Posted by Abbie Salter on 16 May 2010

When I have recently visited the mountains I have seen the orange and brown trees that have been affected by the pine beetles. It is a sad fact that instead of having a two week life cycle, the beetles now have a six month life cycle. This means the amount of damage that the beetles can do is now greatly increased. It seems like most of the mountain now is covered with beetles infected trees. I wish we could let fires burn in the forest to eliminate the beetles without harming any human population. Before reading this article I did not know about the harmed Aspen, if the aspen population was demolished it would severely hurt the populations that live among the roots. I wonder if the real estate market has gone down in these areas that are affected by the pine beetles because of the appearance of the affected trees. If that is true it seems like the mountain habitat has gone downhill in almost every aspect, the pine trees are now sick, the aspen trees are dying, and glaciers are melting. I hope that humans become more aware of the problems in the mountains and give time to find a solution to the many problems founded in these areas. Maybe after awhile we will find a safe solution to kill the beetles without affecting the trees and the surrounding areas in the mountains.

Posted by Anna Schneeberger on 17 May 2010

I fell that I am one of the few people who feels very strongly towards nature and I would place our world and its creatures above myself. I am shocked at some of the numbers reported in this article of tree die-offs especially in Colorado. It is odd though that it is called SAD when it truly is just horrifying that we (humans) have allowed our Earth to become so devastating. We have let things go on for far too long and have not taken action to repair our habitat. It is so sad seeing all the destruction not just for the gorgous view but for the animals' homes that have been lost. I mean, we are part of this Earth and we need to take care of it otherwise our predictions of our world ending soon (maybe not as soon as 2012) may not be too unrealistic. We have been taking advantage of our home and turning it into a garbage dump but the world is a fragile object that is not ‘handled with care’.

It seems people feel that everything could be bigger and better when I feel that the world could never go back to how wonderful it was when humans were not here to "make it better". But yet, there are enough people in this world who do care about our Earth and if every person did one small thing to help the earth, we could make a huge impact towards a better home.
Posted by Kara Videll on 17 May 2010

I'm rather late in discovering this piece but I am very grateful for it. Indeed, worldwide forest die-off is an icon of our difficult times.

There is one important correction that I would like to offer. he record-breaking 2005 drought in Amazonia was NOT an El Nino-triggered event. Contrary to earlier speculations, the drought was driven by the warming of North Atlantic tropical waters:


El Nino is a significant and cyclical Pacific Ocean event that impacts parts of South American but not the Amazon basin which receives most of its rainfall from Atlantic Ocean moisture that recycles as many as 15 times as it travels westward across the great forest.

I have posted a photo of such Atlantic water vapor collected 3,000 km away in Brazil's western-most state of Acre and David Campbell's excellent and majestic description of the Amazon water-cycle at:


Thanks again for an important report and for your excellent work.

Posted by Lou Gold on 22 May 2010

Thanks for the thoughtful and well researched information! We traveled to Colorado this summer and were "blown away" by the devastation to the forests we visited, and in particular to the aspens and lodgepoles. Please check out our "Petition" http://www.thepetitionsite.com/8/climate-change-education-and-the-pine-beetle/ to try to raise awareness on this crisis and if you can, please help us spread the news. As more people make the connection between what they are doing and climate change, perhaps something positive can come out of this horror...

Posted by harriet shugarman on 25 Aug 2010

In My Opinion, It's crucial to allow burning, and for ppl to go in like they used to and cut down these trees and burn them. It used to be a rule of thumb, and it worked. The early signs are EASY to catch to the experienced eye. And I'm sorry, but we are essential to the health of the forest. As we are also dependant upon it's health and well being.

We were designed to take care of our earth, tend to it, and take care of it. And we have failed this mission. The Rich are Too Pre Occupied with making more money, and The rest are too busy trying to suvive, and make it another day. Our laws prohibit us from being more advocates for a more healthier country. If we were to help the poor to find hope and prosperity in the assistance of proactivly being green, we would not only see them turning around, and our country, but the world as well.
Posted by Frances on 07 Sep 2010

The first thing that caught my eye in this article was that many species of beetles are changing and adapting to their enviroment so that they can live longer. It was also suprising that many different types of trees are affected by the beetles including aspen, which I learned that many can be connected to one root source. The main point of this article was that climate change was the main reason the the beetles are able to live longer and reproduce more. I think that if this is the case, it is just another example on how global warming affects our enviroment. If the trees die, then birds or other animals that live in them or eat them will die. Even if climate change is a natural process, humans still need to be aware of what they do and take steps to make a cleaner world. As mentioned in the article, pollution stresses out the trees so if they were healthier, then they might be more likely to survive. Because the beetles are r-strategists, they are able to reproduce quickly because the conditions for doing so are right. If we are able to make a small impact on their enviroment, then maybe they won't have such a large population.

One thing I was curious about after reading this article was about controlled wild fires and the effects of them. I read more about them and learned that controlled burning is a good way to prevent build up of fuel (dead trees) and can prevent larger ones from starting.Fires also can cause some pines cones to break open so it can also be the start of new tree growth. I think that controlled burns would be a good way to keep people safe as the concern of fires was mentioned in the article and make a 'clean slate' for new trees to grow.

Posted by Rhianna Williams on 22 Sep 2010

Pine beetle infestations are a serious issue. I live in Colorado and am astounded every time I go through the rocky mountains. It used to be a wonderful drive up the ski slopes, now it is almost depresing. I do not Know how many times I have heared the term "Go green" in the last couple of years, but I do not think people understand how much wildlife is contributing to environmental issues. If this continues it could be devistating to not only to Colorado but the rest of the United States of America.I believe that the government should be very focused on ending these problems, and suport them financialy until we figure out a solution and finally put a stop to this problem.

Posted by John Moore on 22 Sep 2010

The amount of beetles that have come to America, and the amount that just won't die, is
incredible. They have killed off forest in many parts of the Rocky Mountains. If you have ever
driven through there, then you have seen the masses of red pine trees killed off by the
beetles. I understand that people are trying to kill them, but can't they think faster? We are
running out of time. If this does go on, then we will lose all of our pine trees to the little black
beetle. Nature has helped kill of these little beetles before, but now with global warming,
they are no longer freezing to death. It was the main way they were killed off. So are humans
to blame for this catastrophe?

Posted by Buzz W on 22 Sep 2010

My opinion to this article is that we need to have controlled burnings. We need to have controlled burnings because it will eliminate the trees with beetle kill. Once those trees die the seeds will fall from the tree and new trees will be planted. Then when the new trees grow-up they won't be exposed to the beetle kill. Then to prevent the beetle kill from coming back we need loggers to come up and cut older trees down to eliminate the possibility of the beetles coming back. This wouldn’t happen over night but it would be a good start to stopping the beetle kill. This process would cause a massive decrease in the beetle kill and I would predict if we did the control burnings with the forests that have beetle kill in then even if it is just a small amount that the beetle kill will be eliminated in one and a half decades. So in the big picture this would be the best solution.

Posted by Bailey Schilling on 22 Sep 2010

Ecosystems and habitats are delicate and intricate systems with many components. When just a few more bugs start surviving, or the temperature increases just a few degrees, the whole machine is thrown askew. For example, in this article it is stated that due to increased temperatures, the mountain pine beetles are thriving in Colorado: “It’s not getting cold enough anymore to kill the beetles, which over-winter in their larval stage and survive the milder temperatures because they are filled with glycol, a natural anti-freeze.” Many people argue about the facts of global climate change, but at this point in the debate there is overwhelming evidence to prove of its impact.

Right in our own backyard Rockies glaciers are melting, summers are longer, winters are milder, and it’s not only affecting pine beetle populations. Aspens are dying due to drought, under-watered trees are more prone to disease, and wildfires are popping up everywhere.

To quote the article, “That translates into a drought, and stressed trees are highly susceptible to beetle infestations.” and “[Aspen] groves at low elevations and facing south are dying fastest, and scientists believe the cause is hotter temperatures and drier weather.” Just as the rangers of Rocky Mountain National Park took the sky-rocketed population of elk by the metaphorical antlers, we must now take back our forests. Forests are the habitats in which flora and fauna survive: we must learn how to protect them, since they are “woefully understudied”, as author Jim Robbins put it. Some may argue that nature will run its course and human meddling would steer it astray, but if humans in part caused the pine beetle population to increase, we must also take steps to control it.

Posted by Lily Filipowska on 23 Sep 2010

After reading this article, I see better that it is not just pine beetles that are killing the trees but it is also climate changes. But I disagree that the tempurature can be claimed as rising because we dont have temperature recoreds for over 100 years and we dont know what could happen in the next hundered years. The temperature could rise or drop. If the tempurature drops in the next 100 years instead of rising, will it help the bug population?

Posted by Kaysha Heltslye on 23 Sep 2010

I thought this article was very well laid out and to the point. I agree with the article when it says that the beetles can turn large carbon sinks into carbon sources. It sounds like this is a large contribution to the warming climate with all these trees that would having been taking in the carbon dieing, and releasing the carbon. It's intimidating to think about how pine beetles are contributing so much to the warming climate, and the warmer the climate gets, the easier it is for the beetles to survive.

One thing I disagree with is when the article says that the warming climate is killing off other trees, such as aspens, off too. With an average increase of only 1.8 degrees Fahrenheit I don't think trees would be effected that greatly. Maybe there are other unknown factors that are contributing to the death of other trees. There needs to be more research in this area, and people need to stop putting this off and blaming the warming climate with no research to fully prove this.

One question that I'd have to ask is there more going on here than just the warming of the climate? Could the Beetles just be adapting to colder climates? And could there be some unknown disease killing other types of trees like aspens? As I described earlier, there needs to be more research in this area to answer these questions.

Posted by Drew Van Anne on 27 Sep 2010

An article in response:      
After reading the article “What’s Killing the Great Forests of the American West?” by Jim Robbins I had a few opinions of my own about the article. One of the main points of the article is how climate change is allowing pine beetles to move to higher altitudes in the Rocky Mountains. “’A couple of degrees warmer could create multiple generations a year’” What evidence is there saying this is the only factor causing pine beetles to move up? Perhaps deforestation. What’s the difference between a pine beetle now and one fifty years ago? Pine beetles could have begun to adapt to colder temperatures too.
Hotter temperatures and a drier climate have also been linked to the shrinking forests. “Scientists believe the cause is hotter temperatures and drier weather.” Is there anything that can truly be done if that’s the case? Some scientists say it’s too late to change the effect global warming may soon have. Also how are pine beetles affecting the dry, hot areas in contrast to the cold areas with greater precipitation and humidity? As said by Craig Allen “Forests are complex, and unfortunately, woefully understudied, and there isn’t nearly enough data to draw a conclusion about the reasons behind forest die-offs globally.” If these missing details were researched it would help one better grasp the true effect of all the different factors in Rocky Mountain National Park and elsewhere.

Posted by Ryan Schulman on 27 Sep 2010

I live in Colorado and have seen the devastation to our trees. The orange and brown color at Granby and in Rocky Mountain National Park is not a great thing to go look at. Global warming is not the answer though. The earth may be warming but it isn't affecting the pine beetles in the Rocky Mountains. "These large-scale forest deaths from beetle infestations are likely a symptom of a bigger problem, according to scientists: warming temperatures and increased stress, due to a changing climate," he said. Even though his remarks are well educated, global warming is not the cause of the loss of the pines. This devastation could be caused by too many trees, not enough rain, or just not the type of winters we are looking for. This next winter very well may be the winter that kills off the pine beetles, how would you know? These pine beetles and the loss of the pine trees has the world caught between Scylla and Charybdis. Soon enough, this will be like "The hurricane Katrina of the west coast". No matter if you think global warming is causing this natural disaster or not, everyone is asking the same question: “How do we stop it?"

Posted by Jacob Lewis on 29 Sep 2010

The Earth is self-regulating. However those parameters might not be conducive to human health over the long run. This forum seems to suggest that nature must stay within human parameters of survival in order for nature to survive. Nature will do just fine over time, it's humanity who's survival is shaky.

Posted by Mike on 05 Nov 2010

So much politics! Anything an environmentalist sees is automatically "evidence of global warming".

Bah! The real science simply does not support these conclusions...but I digress...

For any appreciable number of MPB to be killed by cold weather, severely cold weather is required. Either hard freezed early or late in the year -- or sustained temperatures of 30 below! I'm sorry, but these type of temperature conditions have never been common in the mountain region where I have lived all my life.

So, let's get past the political BS and look at real factors. One of the major factors contributing to MPB outbreak is our zealous "protection" of the forest. What I mean by that is vigilatly guarding the forest against natural fires.

Frequent forest fires are a healthy part of the natural cycle. But we do not allow this frequent burning to happen any more. As soon as a fire starts we are jonny-on-the-spot to put it out.

MPB is one of the consequences of our meddling with the cycle. We have created conditions that are very favorable to MBP outbreaks (crowded forests with less diversity).

Now I don't advocate that we just let the forest burn as it will. But we do need to look critically at our overall forest management policies and quit trying to blame it all of "climate shift".

If we continue down the path of blaming everything on imagined global warming, we are going to miss the root cause. And by blinding ourselves to the real problem, we will allow it to continue building.

Posted by Mikey on 08 Mar 2011

Comments have been closed on this feature.
Jim Robbins is a veteran journalist based in Helena, Montana. He has written for the New York Times, Conde Nast Traveler, and numerous other publications. His fifth book, The Forgotten Forest, about the poorly understood role of trees in the environment, will be published next year by Random House.



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