Global warming and the California wildfires


Global warming makes wildfires more likely and more destructive — as many scientific studies have concluded. Why? Global warming leads to more intense droughts, hotter weather, earlier snowmelt (hence less humid late summers and early autumns), and more tree infestations (like the pine beetle). That means wildfires are a dangerous amplifying feedback, whereby global warming causes more wildfires, which release carbon dioxide, thereby accelerating global warming.

The climate-wildfire link should be a special concern in this country where, since 2000, wildfires have burned an area larger than the state of Idaho.

I write this as my San Diego relatives wait anxiously in their hotel room to find out if their Rancho Santa Fe home has been destroyed. This is a beautiful home that I lived in for a month when I moved to the area in the mid-1980s to study at the Scripps Institution of Oceanography.

Can we say that the brutal San Diego wildfires were directly caused by global warming? Princeton’s Michael Oppenheimer put it this way on NBC Nightly News Tuesday:

The weather we’ve seen this fall may or may not be due to the global warming trend, but it’s certainly a clear picture of what the future is going to look like if we don’t act quickly to cut emissions of the greenhouse gases.

Thomas Swetnam, University of Arizona climate scientist, who coauthored a major study on the subject (see below) said in 2006:

We’re showing warming and earlier springs tying in with large forest fire frequencies. Lots of people think climate change and the ecological responses are 50 to 100 years away. But it’s not 50 to 100 years away–it’s happening now in forest ecosystems through fire.

I researched wildfires for my book — hence the “Hell” in Hell and High Water — and my view is closer to Swetnam’s for several reasons.

First, Southern California is experiencing the “driest year in 130 years of recordkeeping,” precisely the kind of extreme weather event we expect from climate change. We are seeing record droughts around the country — and around the world. Some scientists fear we are at risk of shifting the climate to “a permanent drought by 2050 throughout the Southwest.”

Second, we aren’t just seeing bad wildfires, we are seeing record-shattering wildfires. The 2005 wildfire season, which ravaged 8.7 million acres, was record-breaking, and the record it broke was from 2000, when wildfires consumed 8.4 million acres. The 2006 wildfire season easily surpassed 2005, with a stunning 9.9 million acres burned. The 2007 wildfire season is also on a pace to beat 2005.

The August 2006 Science cover story, “Warming and Earlier Spring Increase Western U.S. Forest Wildfire Activity” (subs. req’d) that Swetnam coathored with three Scripps researchers explicitly examined and then rejected the theory that land-use and fire-supression practices were the cause of the surge in wildfires since the mid-1980s.

Some global warming deniers may cross their fingers and call it all a coincidence and criticize the (few) journalists that even raise the wildfire-climate connection. But in fact, a major 2004 study warned that things will get much, much worse if we don’t take action soon to reverse greenhouse gas emissions trends. Researchers at the U.S. Forest Services Pacific Wildland Fire Lab looked at past fires in the West to create a statistical model of how future climate change may affect wildfires. Their work suggests that “the area burned by wildfires in 11 Western states could double … if summer climate warms by slightly more than a degree and a half” centigrade. On our current emissions path, this is likely to happen by mid-century. By century’s end, states like Montana, New Mexico, Washington, Utah, and Wyoming could see burn areas increase five times.

The third reason to worry about the climate-wildfire connection is that wildfires are a classic amplifying feedback, since burning forests release carbon dioxide that accelerates global warming. As the 2006 Science article concludes soberly:

… virtually all climate-model projections indicate that warmer springs and summers will occur over the region in coming decades. These trends will reinforce the tendency toward early spring snowmelt and longer fire seasons. This will accentuate conditions favorable to the occurrence of large wildfires, amplifying the vulnerability the region has experienced since the mid-1980s. The Intergovernmental Panel on Climate Change’s consensus range of 1.5° to 5.8°C projected global surface temperature warming by the end of the 21st century is considerably larger than the recent warming of less than 0.9°C observed in spring and summer during recent decades over the western region.

If the average length and intensity of summer drought increases in the Northern Rockies and mountains elsewhere in the western United States, an increased frequency of large wildfires will lead to changes in forest composition and reduced tree densities, thus affecting carbon pools. Current estimates indicate that western U.S. forests are responsible for 20 to 40% of total U.S. carbon sequestration. If wildfire trends continue, at least initially, this biomass burning will result in carbon release, suggesting that the forests of the western United States may become a source of increased atmospheric carbon dioxide rather than a sink, even under a relatively modest temperature-increase scenario. Moreover, a recent study has shown that warmer, longer growing seasons lead to reduced CO2 uptake in high-elevation forests, particularly during droughts. Hence, the projected regional warming and consequent increase in wildfire activity in the western United States is likely to magnify the threats to human communities and ecosystems, and substantially increase the management challenges in restoring forests and reducing greenhouse gas emissions.

My thoughts are with my San Diego relatives and the stunning half-million evacuees — a Katrina-like exodus. We are simply running out of time to stop all of the carbon cycle feedbacks from intensifying and to stop these devastating, record-breaking wildfires from becoming the normal climate.

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20 Responses to Global warming and the California wildfires

  1. Duke Story says:

    In 1973, when I was in school as a chemistryand biology major we were being lectured about the coming Ice age. At that time, I was employed part time as a fire fighter for the forest service. We all volunteered to go to California to fight the largest fire that had ever hit that part of the world. No one blamed the fire on the Glaciation of the earth and global warming had not yet replaced the global manmade glaciation fad. Now it is Global warming… we blamed the hurricanes on the GW and predicted more to come. Since the Hurricanes have not been forth coming, we have to blame the fires on GW. If this issue were any other “political or religion” type issue the whole thing would be thrown on the ash heap of history but we continue to perpetuate “man made” global warming and blame everything we can on the coming warming so that “someone” can scare the people of the earth into giving away more and more of their freedom to “some national or global regulatory entity”. Global warming may in fact be occurring but if it is we didn’t have any thing to do with it and when the earth decides to cool itself we will not have anything to with that as well. Lets focus on cleaning water, soil and air in the towns and cities we live in. The global warming stuff will take care of itself. We all should have concern for the people who are at risk in these fires. Put global warming where it belongs, an idea and a theory that will be disproved or modified as the environment upon the Earth does what it has been doing for billions of years, going from HOT to COLD and then HOT again.

  2. Joe says:

    Like Dracula, the global cooling myth can’t be killed, but if you want some good rebuttals, try this RealClimate overview post and this one too, as well as this excellent post on “Was an imminent Ice Age predicted in the ’70’s by scientists, in scientific journals?

  3. caerbannog says:

    We all volunteered to go to California to fight the largest fire that had ever hit that part of the world.

    As a lifelong Southern Californian, I remember the 1973 fire season. It was capped by a 200,000 acre fire that burned from Newhall to Malibu. But the ’73 fire season pales in comparison to what we have seen here in recent years (namely the 2003 and 2007 seasons). Factor in monstrous fires in other parts of California (Woodpecker, McNalley, Zaca fires etc), and it becomes clear that fire activity has increased greatly in recent years.

    That single 1973 outlier is a very weak argument against the global-warming/wildfire connection, especially when you compare it with more recent fire seasons.

  4. Jay Alt says:

    Those who volunteered and made a career of it have an entirely different view:

    Expert: Warming Climate Fuels Mega-Fires

    (…)60 Minutes joined up with Tom Boatner, who after 30 years on the fire line, is now the chief of fire operations for the federal government.

    “A fire of this size and this intensity in this country would have been extremely rare 15, 20 years they’re commonplace these days,” Boatner says.

    “Ten years ago, if you had a 100,000 acre fire, you were talking about a huge fire. And if we had one or two of those a year, that was probably unusual. Now we talk about 200,000 acre fires like it’s just another day at the office. It’s been a huge change,” he says.

    Asked what the biggest fires now are, Boatner says, “We’ve had, I believe, two fires this summer that have been over 500,000 acres, half a million acres, and one of those was over 600,000 acres.” (. . . )

  5. Dano says:

    Joe, I’m glad to say we see eye to eye on this issue.

    What I’d like to say about the big fires is that I agree about the record and interpretation, but we should keep in mind the lessons from Elers Koch’s Forty Years a Forester: there were many big fires in the early 1900s, as big as this year.

    We just forget the lessons. We will always have fire.



  6. california says:

    Update on CLOSED ROADS, traffic list for SAN DIEGO:

    1 million fled fires? As the smoke clears, the numbers shrink ;
    27-old arson suspect killed by cops, another arrested

  7. David says:

    “Why are there more of these fires? Turns out the forest service is partly to blame with a policy it started 100 years ago.

    The policy was to put out all fires immediately. “Because we so successfully fought fire and eliminated fire from this ecosystem for a hundred years, because we thought that was the right thing to do, we’ve allowed a huge buildup of fuel in these woods. So now, when the fires get going, there’s a lot more to burn than historically you would’ve seen in a forest like this,” Boatner explains.”

  8. Joe says:

    Yes, but the recent surge in wildfires is largely due to climate change. As I noted, the analysis that Swetnam coathored with three Scripps researchers explicitly examined and then rejected the theory that land-use and fire-supression practices were the cause of the surge in wildfires since the mid-1980s. They did this on the basis of WHERE the wildfires were occurring.

  9. Ron says:

    All that extra carbon dioxide in the air creates more arsonists.

  10. Ron says:

    Here’s one that should be commented upon & debunked by the Believers –

  11. Greg says:

    It is ironic, especially in light of the false information given here, that one of the two primary causes of the California wildfires was COOLING. That’s right – La Niña, which is COOLING of the Pacific, is what shifted the weather patterns and caused the drought we are experiencing that was one primary cause of these fires. And despite the claims you’ve repeated, there is no sign that the La Niña/El Niño pattern is in any danger of freezing into a permanent La Niña and thus causing permanent drought here. On the contrary, assuming global warming continues unabated, we will rather wind up with a permanent El Niño which will bring with it regular downpours, turning San Diego into a lush subtropical paradise.

    I see you admit the last time things were this bad was 130 years ago. Think about what that means for a second. It was this bad BEFORE ANY POSSIBILITY OF ANTHROPOGENIC CLIMATE CHANGE. So your own admission is that it gets this bad 100% NATURALLY.

    Now I see you’ve already dismissed another of the real reasons for the catastrophic fires. You say that someone (no doubt with an agenda) has dismissed the fact, the know, proven fact, that the fires we have are much worse because we’ve disrupted the natural process by which they were regularly burned clear periodically. I’d be careful what I accept as fact if I were you. All anyone who has eyes has to do is ignore what some person who is overzealous about preventing common-sense practices from being implemented and just go out and see for yourself how overgrown the wild spaces in San Diego have become. Common sense alone tells you that more fuel means hotter, harder to fight fires and along with that consider that the overgrowth also complicates rapid access.

    Climate change is real and inevitable. You’d better accept the fact the earth has been warming, more or less, for thousands of years and man is doing little if anything to influence the natural processes behind it. Rising atmospheric CO2 is an effect, not a cause. If I thought it would do any good I’d explain the simple facts behind this truth but since it most likely won’t I’ll just give you a hint or two. Consider what happens to the concentration of a gas dissolved in a liquid as the liquid is heated. Consider the fact that the earth and it’s oceans have been warming naturally since long before man even discovered fossil fuels.

    And a parting question: Which is it you prefer? A gradually warming earth or the next ice age?

  12. Greg says:

    You also reveal your disengenuous nature. There are few if any “global warming deniers”. Those in denial are those who refuse to accept the Earth was warming long before man burned his first gram of fossil fuel. This is how you and those like you keep trying to falsify the argument – you claim that there are people who deny the Earth is warming. That’s not the issue. The issues are twofold. First, is man contributing to global warming and second, if so, is it by any meaningful amount. I suppose a third logical question is whether or not man will change his ways and accept the social and economic consequences if the answers to the first two questions turn out to be yes. Based on the behavior of Al Gore I would say the answer to that third key question is NO!

  13. Greg says:

    Ron Said:

    Here’s one that should be commented upon & debunked by the Believers – articles/ 2007/ 20071024132139.aspx

    The article ask why those who are pushing the various myths such as catastrophic anthropogenic global warming are so intent on scaring us out of our wits with all their gloom and doom rhetoric.

    It’s so we’ll act without thinking, like they do.

    They know if we think it through we’ll see how stupid their positions are.

    It’s that simple – the only way they can possibly hope to accomplish their agendas is through fear and defeatism. Motivate people to believe they’re doomed if they don’t do exactly what they are told.

    No thanks.

  14. Paul K says:

    Joe has been kind enough to occasionally refer to Delayers rather than Deniers. I think I’m part of a large contingent of Insteaders. Were I emperor we would concentrate on eliminating particulate and chemical pollution (clean air, clean water, fertile land) and replacing carbon as a fuel. CO2 reductions, however significant, would be a side benefit. Concerning AGW science, there may be lots to be skeptical about, but the foundation of skepticism must always be an open mind.

  15. fire survivor says:

    My family lived through the devastating 500,000 acre fires in Arizona in 2002. Ours of course were set by two separate individuals. Now everyone is blaming the fires in California on global warming yet the arsonists that set them are being sought. So did global warming warp the arsonists minds and make them start these fires?

  16. Joe says:

    Who knew 2 people could cover 500,000 acres? Seriously. Arsonists can start a fire, but only severe climate conditions (like prolonged drought) can lead to 500,000 acres burning.

  17. Jay Alt says:

    Here is a link summarizing the Scripps research.

    They don’t claim fuel load isn’t a factor. But they show that warming has a stronger influence and is what is driving the spike in big fires.

  18. Jay Alt says:

    Another observation regarding Joes post: White House climate censorship continues –
    the following paragraph was also cut out from the draft.

    “The west coast of the United States is expected to experience significant strains on water supplies as regional precipitation declines and mountain snowpacks are depleted. Forest fires are expected to increase in frequency, severity, distribution, and duration.”

  19. Chauncey Mendez says:

    I very much agree.

  20. blssing says:

    wow.nice picures