Wildfire Burn Areas Expected To Increase By Up To 175% By The 2050s

One of the natural disasters that affects the Western U.S. is, of course, wildfires.  I hope most readers know by now that our 20th century forest management policies had negative impacts on overall forest health.  Today’s forests are too overgrown – an unhealthy condition for the focus of this post: climate change.

I further hope that most readers know that climate change has already had some deleterious effects on Western forests, among them massive die-offspine beetle infestations.  Those effects aren’t likely to slow down any time soon.  Indeed, a recent paper, “Impacts of climate change from 2000 to 2050 on wildfire activity and carbonaceous aerosol concentrations in the western United States” finds an amazing increase in wildfire activity Western U.S. by 2050 under a moderate warming scenario:

We show that increases in temperature cause annual mean area burned in the western United States to increase by 54% by the 2050s relative to the present-day … with the forests of the Pacific Northwest and Rocky Mountains experiencing the greatest increases of 78% and 175% respectively. Increased area burned results in near doubling of wildfire carbonaceous aerosol emissions by mid-century.

Fellow Coloradans: that 175% increase is going to happen in our backyard.

I’m going to highlight what I consider to be the most important point of this result: these results arise from a moderate warming scenario.  By that, I mean this forecast is associated with the IPCC’s A1B scenario, which includes CO2 concentrations at 552ppm in 2050, and which predicts “mean July temperatures to increase by 1.8°C from 2000 to 2050.”  Since the IPCC’s Fourth Assessment Report was issued in 2007, observations have confirmed that we are currently on the worst-case emissions path, known as A1F1 (see the Wiki link for more information).  Unfortunately, a lot of research is being conducted on the A1B scenario and not the A1F1 scenario.  Being on the worst-case scenario track cannot mean anything good for the Rocky Mountain forests, that much is certain.

This study confirms that another positive-feedback loop could be establishing itself.  Climate change is warming up and drying out the region.  This increases the chances that forests will experience more frequent and longer burning fires.  Those fires release additional huge amounts of carbon dioxide, which ensures that the already warmed climate will stay warmer longer as well as increasing warming.  The acceleration of climate change that stoked longer-lived and more frequent wildfires is accelerated even further.

Since I try to combine science with politics in my posts, this is the place to point out that Rep. John Salazar, whose district covers a lot of the area cited in the study, voted against ACES in June.  The same John Salazar who is working against health care reform because “it costs too much” and isn’t “deficit-neutral” voted to subject the Western U.S. to burn areas 5 times as large as they are today.  Where will the money come from to fight those fires and protect people in the future, Rep. Salazar?   Since you’re so anti-investment, what program would you propose we cut to pay for firefighting efforts in 2050 when 35,000,000 acres burn every year instead of 7,000,000?

The good news is the House passed H.R. 2454 and is awaiting Senate approval of their version.  Climate change mitigation at this point in time pays for itself.  That might not always be the case.

Cross-posted at SquareState.

Western Forests Could Become Carbon Source, Not Sink

Human-forced climate change has already many effects that are visible today.  An article that appears in today’s Science introduces another candidate: trees in the Western U.S. are living only half as long as they did 50 years ago.  In the climate most of us grew up in, western forests acted as carbon sinks.  Their growth “scrubbed” carbon from the atmosphere.  Climate change has introduced conditions that are drier than normal; severe drought has ensued across the region.  As a result, trees are growing less and dying earlier than they used to.  That could result in less carbon being removed from the atmosphere, creating yet another positive feedback loop in the climate system.

Researchers focused on what’s called “background” mortality – trees dying from events that do not include infestations of insects like the mountain pine beetle currently afflicting the West, which is identified as “abrupt” mortality.  They studied 76 plots where trees were at least 200 years old.  They were undisturbed by logging (harder to do every year), bark beetle epidemic or wildfire.  Trees being studied in Colorado were largely wiped out by the mountain pine beetle epidemic currently moving across the state’s forests, itself a trend linked to climate change.  Temperature data in the research plots (across the entire West) showed an increase in every season of the year.  The warming and drought conditions we’ve experienced in Colorado has also made its presence felt across a much larger region.

Our forests are suffering from multiple coincident effects of a warming planet and regionalized drying.  Direct human pressures such as increased population in the inter-mountain West and hundreds of years of logging aren’t helping matters.  Efforts need to be made today to decrease our forcing on the climate system.  Carbon emissions need to be drastically reduced so that concentrations in the atmosphere can be reduced later this century.  If forests are unable to play their historic role of a carbon sink, those efforts become all the more critical.  Unfortunately, it will likely increase their cost, something environmentalists cited regularly during the past eight years’ of climate inaction.

The Denver Post has, surpringly to me, a pretty good article on this.  Joseph Romm (Center for American Progress Senior Fellow & Climate Progress blogger) has a more scientifically-rigorous discussion of the article and its implications.  I recommend reading Romm’s analysis if you don’t want to read the article itself.

Cross-posted at SquareState.

[Update]: While reading the article again, something important popped out at me. The authors note the following:

From the 1970s to 2006 (the period including the bulk of our data; table S1), the mean annual temperature of the western United States increased at a rate of 0.3° to 0.4°C decade -1, even approaching 0.5°C decade -1 at the higher elevations typically occupied by forests.

So between 1.2°C and 2°C warming has already occurred since the 1970s.  That means the forests of the future are in for bad times.  If we could somehow magically stop emitting greenhouse gases today, the climate system would still get warmer for the next 100+ years due to the forcing “in the pipeline”, as climatologists refer to it.  The climate system hasn’t fully responded to the gases emitted in the last 5, 10, or 50 years.

Of course, no such magic is going to occur.  Emissions will have to stop increasing (stabilize) then start decreasing.  Which means there is plenty of additional forcing (warming) that will occur.  The 2007 IPCC assessment relied on models that didn’t demonstrate the warming that has already occurred very well.  Policy decisions based on that report would therefore be poorly suited for the task we face.

[2nd Update]: NPR’s Science Friday discussed this paper with one of the researchers today.  The segment can be found here.