I've been concerned about climate change for decades, but in the last several years it's gradually slipped from the front of my mind. It is easy to think of climate change as a problem for someone else who is far away–either geographically or in time. We hear about the melting of the ice caps and the negative effects of sea level rise on coastal communities, but these problems are easy to forget about when you live in a landlocked state like Colorado.   

The 2020 wildfire season across the Mountain West has been more than a little disturbing, with four states shattering records for total land area burned in a single year (CA, CO, WA, OR). Is it a coincidence that this happened in a year that is tied as the warmest on record?  This past summer brought climate change back to the absolute forefront of my mind.  No other event in my lifetime has made this unavoidable truth more obvious:
Climate change is real.  It is happening right now, humans are the cause and it will get worse.
This article describes the 2020 Wildfire season in Colorado and across the US Mountain West and its connection to climate change.  It is divided into six major sections. 
  1. California: A Canary in the Coal Mine
  2. Sept 7-8, 2020: Once-in-a-Century Weather Across the US Mountain West​​​
  3. The Rest of Colorado's Wildfire Season
  4. The Future of Colorado?
  5. Our Place in History
  6. What to do about it? ​
I suspect that many but not all readers will have either experienced Colorado's drought and wind-driven fire season personally or are already familiar with the connection between mega-wildfires and climate change.  In this case, you can skip Secs. 1-3 and start with Sec. 4 where I discuss a possible future for Colorado's wildlands.    

Sources for all facts and statistics are given as hyperlinks throughout the article.  Figures that I personally created are marked with my initials, TB.  Figures taken from other sources are compiled in the References section at the end.   Additionally, I've compiled an extensive list of recommended material that are outside the scope of the present article in "Further Exploration".  

1. California: A Canary in the Coal Mine

The western United States has a significantly drier climate than the eastern half of the country. One of the consequences of consistently warm and dry summer weather is an elevated risk of wildfires. No state embodies this risk more than California, which typically has a more active wildfire season than any other state. In addition to the buildup of large amounts of dry fuel, CA wildfires are exacerbated by the local weather patterns.  The most prominent example of these weather patterns are the downslope Santa Ana winds in southern CA which can reach speeds of 100 mph. Not only do these winds cause rapid fuel consumption by injecting oxygen into existing fires, they also carry embers over long distances complicating containment efforts.

The inherent susceptibility of CA to large wildfires acts as a magnifier of climatic variations.  This year, CA experienced its most active fire season to date on the heels of the warmest August-October in history (Fig. 1). At year's end, CA has burned 4.18 million acres, more than 2.5x the mind-boggling previous record set in 2018. It is no coincidence that five of the six largest fires in California history were in 2020 (Fig. 2).  
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Figure. 1. California August-October average temperatures from 1895-2020. 2020 is the warmest year on record for this period. Source: Daniel Swain, @WeatherWest, Ref 1.
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Figure 2. Correlation of average climate and wildfire severity in California from 1895-2020. Source: Berkeley Earth, Ref 2.
California's 2020 wildfire season started earlier than usual when a series of unseasonal lightning storms in northern California ignited numerous fires which eventually merged to form so-called “complexes”. The three largest complexes, the SCU Lightning Complex, the August Complex, and the LNU Lightning Complex would burn 2.1 million acres in a three-week period.   GOES-17 satellite imagery loops from CIRA/RAMMB of these fires are shown in Figs. 3 and 4.  
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Figure 3. GOES-17 imagery of CA wildfires on Sept 05, 2020. Note the August Complex in northern CA and the exploding Creek Fire to the south. Source wikipedia. Ref 3.
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Figure 4. GOES-17 visible imagery overlaid with The three largest fires started by unseasonal lightning storms in northern California: the August complex, the SCU complex and the LNU complex. Source: Dakota Smith (@Weatherdak), Ref 4
California's Creek Fire
Further south, the Creek Fire erupted in the foothills of the Sierra Nevada mountains on Sept 04 and grew rapidly on Sept 05 (Fig. 5). This spawned numerous extreme wildfire activities, including possibly the largest pyrocumulonibus (PyroCb) cloud in US history.  Radar analysis of the smoke plume by University of Nevada, Reno professor Neil Lareau indicated that it reached 55,000 feet into the atmosphere, nearly twice cruising altitude of commercial passenger jets.  PyroCb clouds form over regions of intense heat such as wildfires and volcanic eruptions and for fires, serve as both an indicator and driver of extreme fire activity.  The Creek Fire PyroCb spawned two tornados and numerous lightning strikes (Fig. 6).  Before containment, the Creek Fire burn area reached 379,895 acres, making it the largest single origin fire in CA history.

​In all, CA would experience 8,112 wildfires in 2020.
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Figure 5. Explosive growth of the Creek Fire and formation of its pyrocumulonibus (PyroCb) cloud on Sept 05, 2020. Source: Dakota Smith (@Weatherdak), Ref 5.
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Figure 6. After the Creek Fire PyroCb column collapsed, the cloud would trigger at least two tornados and numerous lightning strikes. Source: Dakota Smith (@Weatherdak), Ref 6

2. Sept 7-8, 2020: Once-in-a-Century Weather Across the US Mountain West

If CA is the canary in the coal mine, what does that make the rest of the western US?
​
In the second week of September 2020, the mountain west experienced several simultaneous once-in-a-century weather events: 1) extreme drought, 2) record heat waves, 3) massive wildfires and 4) a typhoon in the Pacific Ocean that was injecting energy into the jet stream and driving a record-breaking early season snow storm (Fig. 7).  
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Fig. 7. GOES-17 satellite imagery of the western United States near sunset on Sept 07, 2020. Near the Wyoming-Colorado border, you can see the strong pyrocumulonimbus cloud from the Cameron Peak fire. The snow would temporarily slow it down but when the snow melted it came back. Loop created by Daniel Swain from CIRA/RAMMB imagery. Source: Daniel Swain/@Weather_West. Ref 7.
Parts of the West had been in a significant drought since the spring and by September 22% of the contiguous US was experiencing a severe or extreme drought (Fig. 8).   This was driven in part by a heat wave that led to Earth's warmest September on record.  In the United States, this was, expectedly, felt most acutely in California.  Extreme heat in southern California broke single-day records and Death Valley experienced possibly the hottest temperature ever measured on Earth.  ​​​
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Figure 8. US drought conditions from. January - December 2020. Pay special attention to Sept-Oct. Animation loop by TB using plots downloaded from www.droughtmonitor.unl.edu.
Figure 9 shows thermal GOES-17 satellite imagery of the approaching cold front from Sept 6-9, 2020.   The bright orange areas correspond to infrared heat signatures, not visible flames.  
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Figure. 9. Thermal GOES-17 imagery of the western United States from Sept 06 - Sept 08, 2020. Heat signatures from large simultaneous wildfires can be seen in Washington, Oregon, California, Idaho, Utah, Wyoming, and Colorado. High winds that precede the cold front moving from the north drive explosive fire growth. Animation loop by TB.

The Pacific Northwest

On Sept 06. NOAA predicted that the Pacific Northwest would experience extreme fire danger starting on Sept 07.   As expected, the high winds that preceded the arrival of the cold front drove explosive fire growth in both states (Fig. 10).   Strong winds had already caused the Cold Springs Fire in central Washington to move 55 miles due south on Sept 07 and as the front moved closer, the changing wind direction drove rapid growth to the southwest (Fig.  11).  This can be thought of as an extreme version of blowing on kindling to start a campfire.  WA Gov Jay Inslee reported that the single-day fire storm burned 330,000 acres, exceeding the annual totals for the 12 previous years.  By the end of the year WA had a new record for total acres burned: 713,000.  
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Figure 10. Wind-driven fire growth in the Pacific Northwest on Sept 07, 2020 as the cold front moves south. Time span = 13 hours, sunrise - sunset. Animation loop by TB.
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Figure 11. Enlargement of wind-driven fire growth in Washington in the evening on Sept 07, 2020. The long fire in the middle is the Cold Springs Fire. Animation loop by Dakota Smith, @Weatherdak. Ref 8
To the south, the combined effect of the wind storm and prolonged drought conditions were sufficiently rare that it marked the first time that the NWS Storm Prediction Center issued its most serious fire warning for western Oregon, an area that is typically too wet to have have large wildfires.  The new wind pattern drove the preexisting Lionshead Fire due west where it would eventually merge with the Beachie Creek Fire. ​ A troubling consequence of large fires in regions where they are unexpected is that the wildland-urban interface is typically not prepared for them, in contrast to a rural area with a long history of wildfires.  This is starkly demonstrated by Dakota Smith's satellite imagery loop (reproduced below) which combines daytime imagery with nighttime imagery showing light pollution from urban centers.  Note the long and skinny Almeda Fire near the town of Merced in southern Oregon.   
Although this fire was not particularly large it did enormous damage to homes and businesses, as shown in the NYT video below.  Across Oregon, wildfires would lead to the evacuation of 500,000 people and over 1 million acres burned.  Imagery before and after the Sept 2020 Oregon wildfires are shown in Fig. 12.
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Figure 12. Before and after the Sept 2020 Oregon wildfires. Source: Dakota Smith/@Weatherdak, Ref 9.

Colorado: The Cameron Peak Fire

Colorado's Cameron Peak Fire started on August 13, 2020 on the eastern side of the Rawah Range, in an area popular with backpackers (Rawah Wilderness). Even though this fire appears to have been caused by humans, the combination of hot and dry weather, overgrown forests and widespread, climate-driven beetle kill, created near-ideal fire conditions. It grew at a moderate pace for nearly a month, eventually reaching the northwestern boundary of Rocky Mountain National Park.  

​During the first week of September, temperatures in Colorado were consistently 2-4 degrees Fahrenheit above normal across the state (see this and this), and Denver had seen more days above 90 degrees F than any other year.   In Colorado, this heat dome reduced water vapor content in the air, which in turn pulled water out of the ground and vegetation.  This evaporation effect and the lack of new precipitation was sufficient to put the state in a drought despite a spring snowpack level near 100%.
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Figure 13. Extreme temperature swings in Boulder Colorado from Sept 05-10 from BoulderCAST. Ref 10
As this storm moved south out of Canada, it was predicted to bring over 1 foot of snow to Colorado's Front Range, but it was unclear how much of that snow would stick to the ground.  Historically, meteorologists have not had to worry about modeling a snow storm in areas where the ground temperature has been warmed by 90°F weather.   The Boulder branch of the National Weather Service had nothing in the 120-year instrumental record to evaluate their models against (see this as well for a retrospective from BoulderCAST).      The storm broke numerous records in Boulder, including a record high that was followed by a record low 24 hours later (Fig. 13). 
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Figure 14. The Cameron Peak Fire burning in the Mummy Range within Rocky Mountain National Park on Sept 06 2020. Source: Bloch/@JasonBloch, Ref 11.
The fire was burning relatively weakly on the morning on Sept 06, but new winds from the the cold front drove explosive growth of 25,000 acres of fire burning within 24 hours (Fig. 14). This trend accelerated on Sept 07 leading to an intensifying PyroCb cloud and another 40,000 acres burned in 24 hours.  On Sept 08, the dropping temperatures and rain and snow from the cold front stalled fire growth. (Figs. 15 and 16).  When the snow melted a week later, embers reignited the fire and a little over a month later, the fire experienced explosive wind-driven growth once again.  More details on fire growth including progression map are given in Sec. 3. 
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Figure 15. Snowfall in Boulder Colorado on Sept 08, 2020. This regional snow storm was sufficient to put the Cameron Peak Fire on hold, but not put it out. Photo by TB.
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Figure 16. The arrival of the cold front temporarily extinguished the East Fork Fire in Utah and the Cameron Peak Fire in Colorado. The imagery covers Sept 06-08, 2020. Animation loop by TB.
Extreme weather events like these were considered rare in the last century.  Will they stay that way into the next?

3. The Rest of Colorado’s Wildfire Season

I was motivated to write up my thoughts back in September, thinking that the snowfall on Sept 07 would mark the end of an already terrible wildfire season in Colorado.  Unfortunately, extremely rugged terrain and sleeping embers prevented complete containment of the Cameron Peak Fire.  The fires had lasted until fall, and high winds had the capability to drive explosive growth.

Undoubtedly, the worst of Colorado's wildfire season was yet to come.  

​In the remainder of this section I'll discuss the three most prominent fires in Colorado's Front Range: The Cameron Peak Fire, The East Troublesome Fire, and the Calwood Fire.   A map of the major fires in Colorado in 2020 is shown in Fig. 17.  
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Figure 17. A Map of the land area burned in Colorado's 2020 wildfire season.

A resilient Cameron Peak Fire...

Once the snow melted from the September snow storm, the Cameron Peak Fire returned. Fire activity would follow a familiar pattern: mostly smoldering slow expansion punctuated by explosive wind-driven growth.  On Oct 16, wind speeds were gusting at nearly 40 mph, driving 38,000 acres of new growth in 24 hours (Fig. 18).  Behavior on Oct 17 and 18 were similar as it became the first fire in Colorado history to reach 200,000 acres.  
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Figure 18. Color coded progression map of the Cameron Peak Fire. Purple shades = earlier, orange = later. The source map was created by the National Interagency Fire Center, Ref 12. I have added annotations for the dates of days experiencing explosive wind-driven growth are labeled with white text.
For almost all of us, it's hard to get a sense of just how awful the conditions are for fire fighters and what an uphill battle they are facing.  The video below  from the Colorado Division of Fire Prevention and Control  fire crew of one of their fire crews helped me get a sense of that.  Their caption is worth reading.

The East Troublesome Fire

The East Troublesome Fire started on Oct 14, 2020 on USFS land in Grand County, on the western side of the Continental Divide.  On October 16, smoke from the East Troublesome Fire joined with smoke from the Williams Fork Fire and made its way to Boulder creating eerie orange skies (Fig. 19) and horrible air quality (AQI > 400).  Just ten months earlier when I'd seen photos of similarly orange skies from the catastrophic wildfires in Australia which burned 46 million acres, I thought, "that's terrible, but that will never happen here."  
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Figure 19. This is what climate change looked like in Boulder, Colorado on Oct 16, 2020. The Flatiron formations themselves are completely obscured by the smoke. Most of this smoke was from the WIlliams Fork Fire and East Troublesome Fire on the other side of the continental divide. Photo credit: NOAA, Ref 13.
Like the Cameron Peak Fire, the East Troublesome fire was fueled by widespread drought, extensive downed beetle-kill trees and, of course, high winds.  This led to the most alarming fire behavior of 2020 in Colorado and possibly the entire US.  On Oct 21, the fire grew by 140,000 acres in a 24-hour period leading to widespread mandatory evacuations in Grand Lake, CO (Fig. 20).    Like the large runs of the Cameron Peak Fire a month before, this growth was again driven by high winds preceding an incoming winter storm.  
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Figure 20. The East Troublesome Fire from the air. I believe this widely shared photo was taken by a passenger on a commercial airline flight but I have not been able to determine the original photographer. If you know who it was, let me know.
On Oct 22, when high winds carried embers 0.75 miles across the treeless continental divide to seed new fires in Forest Canyon in Rocky Mountain National Park (Fig. 21) , Estes Park was pre-emptively evacuated in fear that the East Troublesome Fire would merge with the Cameron Peak Fire.   Before the human caused Fern Lake Fire in 2012, Forest Canyon had not experienced a fire in 800 years.

​(FYI, professional photographers Alan and Leanne Shadduck, who own the print company Images of Estes Park, have a truly stunning photo for sale that features an elk drinking from Lake Estes under orange skies with McGregor Mt in the background.)  ​​
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Figure 21. The East Troublesome Fire in Rocky Mountain National Park. On Oct 21 2020, high winds blew embers 0.75 miles across the treeless continental divide to seed fire growth in Forest Canyon. Map by TB.
A fire progression map by Technosylva's Joaquin Ramirez (reproduced below) captures both the Cameron Peak and the East Troublesome Fire and makes the large wind-driven acreage gains clear.  If you blink, you'll miss the East Troublesome Fire at the end of the animation.
This second snow storm was considerably larger than the storm on Sept 07, and the East Troublesome Fire did not experience a significant resurgence.   By the time the East Troublesome Fire was contained, 193,812 acres had burned, 366 homes and 214 outbuildings and commercial structures were destroyed and 2 lives were lost.

The Calwood Fire

On Oct 17, the day after Boulder's orange skies, the Calwood Fire started in the foothills near Lyons, about 10 miles NW of Boulder; see Fig 22 for a photo from NCAR.  The fire appears to have started somewhere on the Cal-Wood property west of Fairview Peak.  
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Figure 22. The Calwood Fire burning in Central Gulch behind Fairview Peak. Looking north from NCAR at 1:30 pm on Oct 17, 2020. Photo by TB.

As the fire burned in the dense, overgrown forests of Central Gulch,  it developed its own massive PyroCb cloud with clear evidence of counter rotating vortices.  ​According to Neil Lareau at UNR, there are three impacts of these vortices: "(1) leading plume edges can cause tornado strength rotation linked to the fire, (2) trailing vortices pendant from the under side of the plume and traveling away from the fire are possible, (3) long-range spotting can occur."  A 5 minute time lapse created by Fox 31 meteorologist Brooks Garner is shown in Fig. 23.  Such phenomena were thought to be quite rare in previous decades.  The level of video and radar documentation for this event is a testament to the increasing frequency of extreme wildfire behavior overall as well as the presence of people in close proximity due to rapid growth of wildland-urban interfaces throughout the US.  
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Figure 23. 5 minute time lapse of the Calwood Fire from Fox31 meteorologist Brooks Garner. (@brooksweather). Source Ref. 14

​In the first day, the Calwood fire burned 5837 acres, the majority of which occurred over just a few hours.  As the fire moved down the eastern slopes of Fairview Peak and UN 8315' towards US 36, it destroyed 18 homes.  Daniel Swain from UCLA and NCAR said "Even as a scientist studying extreme weather & wildfire in a warming climate, I was shocked by how fast #CalwoodFire roared down the Colorado Front Range foothills this afternoon." Thanks to a rapid response from firefighters and new precipitation on Oct 18, the majority of the growth of the Calwood was confined to a single day; see Fig. 24 for a photo of the fire on the evening of Oct 17.   Fire crews reached 100% containment on Nov 15, 2020 after it had burned a total of 10,108 acres, making it the largest fire in Boulder County history.
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Figure 24. The Calwood Fire on Oct 17, 2020 at 10:30 pm. Looking NW from Diagonal HW and 55th St. Photo by TB.

4. The Future of Colorado?

 There is nothing normal about the wildfire activity in the West in 2020.  Colorado has never had a fire season like this one.   Before the 138,000 acre Hayman Fire in 2002, Colorado had never had a 100,000 acre wildfire. In 2020, Colorado reached this threshold three times:
  1. Pine Gulch Fire: 139,007 acres
  2. East Troublesome Fire: 193,812 acres
  3. Cameron Peak Fire: 208,913 acres​

In total, more acres were burned in Colorado wildfires in 2020 than in any other five-year period combined.   Disturbingly, this appears to be part of a recent trend.  All of the largest fires in Colorado history have been in the last twenty years and if you remove the Hayman fire in 2002 they've all been in the last ten years. 
You may have noticed the curious eastern boundary (Fig. 25) of the Cameron Peak Fire and wondered what caused it.   Upon closer inspection it becomes evident that this boundary is coincident with the burn perimeter of the 2012 High Park Fire.  The fire stopped because it had run out of fuel because there was simply nothing left to burn (Fig. 26).  ​
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Figure 25. The curious NE boundary of the Cameron Peak Fire is the result of running into the perimeter of the 2012 High Park Fire and exhausting the available fuel. Map by TB.
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Figure 26. Looking towards west Commanche Peak from White Rock (8784') just outside the Cache La Poudre Wilderness in May 2019. The burn scar on the left is from the 2012 High Park Fire. The green, living trees in front of the snow-covered peaks were nearly completely burned in the Cameron Peak Fire. Photo by TB.
You can see more pictures of the High Park Fire from my trip to the Cache La Poudre Wilderness here.  The entire region between Fort Collins and the Rawah Wilderness has now burned within the last eight years, amounting to a continuous strip of land of approximately 12 miles wide and 36 miles long.  This is terrifying.  I predict that it is a matter of decades or less until essentially all of the forests between the Continental Divide and Front Range cities like Boulder, burn. ​
Certainly one factor that is exacerbating wildfires in northern Colorado is the Mountain Pine Beetle (Fig. 27).  Under normal conditions, 98% of pine beetle larvae are killed in the winter but a warming climate has led to a longer reproductive season.  Additionally, poorly managed, overgrown, monoculture forests make it easier for beetles to move tree to tree.   This has resulted in dead, downed trees over large regions of Colorado and across the greater Rocky Mountains, making every forest a tinderbox. In Colorado alone, 3.4M acres have been lost to beetle kill since 1996.  Much of my treasured Gore Range, has been completely devastated by the pine beetle (Figs. 28 and 29).  What will Colorado wildernesses look like in another 20 years?  ​
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Figure 27. Mountain Pine Beetle (Dendroctonus ponderosae). Photo from Wikipedia.
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Figure 28. Extensive beetle kill in sub-alpine forests in the eastern Gore Range in late summer 2020. Anecdotally, the fraction of dead to live trees in the Gore Range appears quite similar to that in the area where the East Troublesome fire burned most intensely. Photo by TB.
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Figure 29. Part of the beetle kill problem can be traced back to monoculture forests where virtually every tree is susceptible. The eastern Gore Range, late summer 2020. Photo by TB.
However, climate change can cause catastrophic fires even in the absence of beetle kill.  One of the best climatic predictors of wildfire severity is the vapor-pressure deficit (VPD), which in contrast to relative humidity is a measure of the absolute water vapor content in the air (Fig. 30).  It is defined as the difference between the saturation vapor content and the actual vapor pressure so that larger values of VPD indicate dryer air.  An October 2020 study found that 56% of the variability in burned area can be correlated to variations in the VPD (see this for a cheesy video summary of the paper).  

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Figure 30. One of the strongest predictors of land area burned by wildfires is the vapor-pressure deficit (VPD) which is a measure of water-vapor content in the air. Larger values of VPD indicates dryer air. Researchers have found that 56% of the annual variability in land area burned by wildfire is correlated with variations in VPD. Figure from Higuera and Abatzoglou "Record‐setting climate enabled the extraordinary 2020 fire season in the western United States" published in 'Global Change Biology' in October 2020. Ref 15.
Boulder's Calwood fire is especially relevant to the issue of VPD.  I know firsthand from my hikes in the area that those forests were free of beetle kill in stark contrast to the forests where the East Troublesome fire burned most aggressively.  Instead, the Calwood fire was the result of dense fuel that had been dried in a heat wave and a drought and then driven by high speed winds in the fall.  Furthermore, it seems possible that Colorado's fire season will continue to merge with stronger autumn winds as has happened in CA.  The westerly Chinook winds blowing from the foothills into Front Range cities could begin to play a similar role as the Santa Ana winds in CA.  ​​​
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Figure 31 (a). The burned area of four intense wildfires lower montane ecosystems near the South Platte River (SW of Denver): Buffalo Creek (1996), High Meadows (2000), Snaking (2002) and the Hayman Fire (2002). The Lost Creek Wilderness lies immediately to the west of the Hayman Fire. Map by TB
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Figure 31 (b). After approximately 20 years, these lower montane forests have yet to regenerate due to a warmer and drier climate. See main text for links to peer reviewed studies. This satellite imagery is from 2016. More recent (lower resolution) imagery shows similar trends. Map by TB
Most importantly, it appears that the forests aren't growing back from these intense wildfires. In a healthy wildfire, fire growth is contained along the ground and primarily affects the vulnerable, young trees.  Old growth trees with thick bark typically survive.  In contrast, high-intensity crown fires, which are becoming more common, are sufficiently hot to burn the canopy of old growth as well as vegetation on the ground. Eighteen years after the 2002 Hayman Fire outside of the Lost Creek Wilderness, new tree growth has yet to appear because the old growth trees that previously provided shade to protect new growth were killed (see peer-reviewed studies: #1, #2 and #3. #3 is especially relevant). See Fig. 31 (a) for a map of the burn perimeters of the 1996 Buffalo Creek Fire, the 2000 High Meadows Fire, the 2002 Snaking Fire and the 2002 Hayman Fire. Recent satellite imagery (Fig. 31  (b)) confirms that these areas have yet to recover 20 years later. A photo of the Buffalo Creek Fire burn scar from one of my trips is shown in Fig. 32.  

Even before the Calwood fire, large portions of the burned area around Fairview Peak and Golden Age Peak off of Lefthand Canyon were devoid of any new tree growth in the 17 years after the 2003 Overland Fire which burned a nearby region (see Fig. 33). Why? It's too hot and dry. The basic phenomena at work here should be familiar to anyone who has looked for intermittent streams to refill water bottles when backpacking in Colorado summers. In my experience, on hot days your chances of finding an intermittent stream with flowing water in an area with direct sunlight is essentially zero. If you happen to pass through a densely forested, shady region, your luck goes up greatly. This is simply a tough environment for new trees to become established because precipitation evaporates too quickly.
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Figure 32. 24 years after the the Buffalo Creek Fire (1996), the forests have not recovered. This photo by TB (May 2019).
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Figure 33. Similar trends in absence of new tree growth in Spruce Gulch, west of Fairview Peak are present 17 years after the 2003 Overland Fire. This area burned again in the Calwood Fire. Photo by TB (June 2020).
Most of the news coverage of the wildfires is focused on property damage and lives saved or lost. This is important and tragic for those involved but it misses the bigger picture and the grim outlook for all of us in the years ahead. It appears that Colorado is on track for wildfire seasons that are not too different from how what California experienced 20 years ago.  Will constant smoke become commonplace annually from August-September?  Even into October?   Outdoor recreation, in the form of tourism and as a motivation for businesses to relocate here, is a key ingredient in Colorado's healthy economy.  It is hard to see how this continues if its most alluring wildernesses and its biggest cities are filled with smoke.  ​ 
To limit the scope of this article, I have decided not to discuss the impact of climate change on our winter snowpack, shrinking glaciers or water availability in the Colorado River basin but this is not to minimize their importance.  A particularly visible sign of this has been the retreat of the Arapaho Glacier in Indian Peaks Wilderness which makes up a significant part of Boulder's water supply.  As of 2007, the glacier had lost 52% of its ice since the start of the 20th century; see Figs. 34 (a) and (b).  (See this interactive side by side version of Figs 34(a) and (b) on the Boulder Data Hub)
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Figure 34 (a). The Arapaho Glacier in 1898.
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Figure 34 (b). The Arapaho Glacier in 2003.
There's a fable about how you can put a frog in a pot of water, and as long as you increase the temperature slowly enough, you can boil the frog without it jumping out. Is the Front Range the frog? 

5. Our Place in History

You often hear things like "the climate is changing all the time" or "humans have little power to change the climate".  This is, unfortunately, simply untrue. The earth has been in a goldilocks zone of +/- 0.5 degrees C for the last 10,000 years called the "holocene" which began at the end of the last ice age (Fig. 35).   (This is calculated from a 30-year average, so many summers and winters get blended together). The impact of the holocene could not have been more profound. It allowed our ancestors to develop farming and settle down to build communities and indeed, all human civilization as we know it.  By burning millions of years of dead plants and animals in the form of fossil fuels over the last ~100 years, we have generated enough warming to cause the earth to leave the holocene.  A detailed view of the last 170 years is shown in Fig. 36. 

Human civilization is now in completely uncharted territory.  
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Figure 35. The earth has enjoyed a period of remarkable climate stability 10,000 years called the holocene. In only 100 years, humans have generated enough global warming to cause the earth to leave the holocene. Ref 17.
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Figure 36. An enlargement of the period temperature variations of the last 170 years. Ref 18.


It's really a shame no one introduced the basic physics of climate change in the 1890's (Fig. 36) or testified to congress in the late 80's (Fig. 37).
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Figure 36. In 1896, Svante Arrhenius made the first calculation of the global warming that would result from a doubling of atmospheric carbon dioxide concentrations. Ref 19.
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Figure 37. The New York Times ran a story about a James Hansen's 1988 testimony to congress with the headline "Global Warming Has Begun, Expert Tells Senate". Ref 20

6. What to do about it?

There are many causes and complicating factors that affect mega-wildfires.  Human caused ignitions, fuel density, beetle kill and climate change are all important factors determining the current wildfire conditions.  I've chosen to focus on climate change in this article because I think it is an existential threat facing humanity.  I realized that just as California was a canary in the coal mine for megafires throughout the West, the West's megafires are a canary in the coal mine for a fundamentally changed planet.  (The true canary in the coal mine for climate change is the arctic, but I'm limiting this article to the US Mountain West).

Over the summer in 2020, I worried constantly about the future of Colorado, the West and the entire planet over the remainder of my lifetime.  More importantly I worried about the future I was going to leave to my niece and nephew (Shiloh, age 5 and Khoi, age 8).   What about their children?  
What could I do? I drive as little as possible during the week, which is hopefully enough to offset my trips to the local mountains.  I'm working on eating less meat.  And, critically, I vote.   Unfortunately, the impact of any single person adopting these changes is small.  Was there something else?  As I searched for an answer, I came across a TED talk from Kathryn Hayhoe, a professor at Texas Tech in Lubbock, Texas who offered a simple answer: "The most important thing you can do to fight climate change is to talk about it."    

I realized that I had not had a serious conversation about it in years.  This is part of my attempt to remedy that.  I hope you'll join me.

References

  1. California August - October temperatures, 1895-2020 (Daniel Swain, NOAA)
  2. California wildfire intensity correlates with warm + dry weather (Berkeley Earth) 
  3. GOES-17 imagery from CIRA/RAMBB of California wildfires on Sept 05, 2020 (Wikipedia)
  4. GOES-17 imagery from CIRA/RAMBB of Northern California Fire complexes (mixed dates).  (Dakota Smith, @Weatherdak)
  5. GOES-17 imagery from CIRA/RAMBB of the Creek Fire on Sept 05, 2020.  (Dakota Smith, @Weatherdak)
  6. GOES-17 imagery from CIRA/RAMBB of lightning strikes produced by the Creek Fire on Sept 05, 2020  (Dakota Smith, @Weatherdak)
  7. GOES-17 imagery from CIRA/RAMBB of wildfire smoke and approaching cold front on Sept 07, 2020 (Daniel Swain, @Weather_West)
    1. Daniel Swain's explanatory thread is definitely worth reading.   
  8. GOES-17 imagery from CIRA/RAMBB of explosive wind-driven growth of Cold Springs Fire on Sept 07, 2020 (Dakota Smith, @Weatherdak)
  9. GOES-17 imagery from before and after the 2020 Oregon wildfires (Dakota Smith, @Weatherdak)
  10. "Hot, Cold & Snowy: A look back at the record-shattering wild week of "summer" weather."  BoulderCAST blog post.  t
  11. Aerial Photo of the Cameron Peak Fire by Jason Bloch (@JasonBloch)
  12. ArcGis story map of the Cameron Peak Fire produced by the National Interagency Fire Center
  13. NWS Boulder
  14. 5 minute time-lapse of vortices in the Calwood Fire smoke plume by Fox 31 Meteorologist Brooks Garner (@brooksweather)
  15. Philip E. Higuera and John T. Abatzoglou, Record‐setting climate enabled the extraordinary 2020 fire season in the western United States. Glob. Change Bio. 2021:27:1-2.  https://doi.org/10.1111/gcb.15388
  16. Glaciers, Climate Change, and Sea-Level Rise, NASA Earth Observatory
    1. ​See also:  Benjamin D. Haugen, Ted A. Scambos, W. Tad Pfeffer & Robert S. Anderson (2010) Twentieth-century Changes in the Thickness and Extent of Arapaho Glacier, Front Range, Colorado, Arctic, Antarctic, and Alpine Research, 42:2, 198-209, DOI: 10.1657/1938-4246-42.2.198
  17. Earth's temperatures over the last 12,000 years.  Plot by Stefan Rahmstorf, an IPCC author.  The plot itself a compilation of data from the following sources:
    1. Shakun, J., Clark, P., He, F. et al. Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation. Nature 484, 49–54 (2012). https://doi.org/10.1038/nature10915
    2. Marcott, S.A., Shakun, J.D., et al. A Reconstruction of Regional and Global Temperature for the Past 11,300 Years, Science, (2013): Vol. 339, Issue 6124, pp. 1198-1201 http://doi.org/10.1126/science.1228026
    3. NASA GISS Surface Temperature Analysis, (GISSTEMP v4) https://data.giss.nasa.gov/gistemp/
  18. Intergovernmental Panel on Climate Change (IPCC) Special Report: Global Warming of 1.5 ºC, Chapter 1, page 57.  
  19. Arrhenius, S. On the influence of carbonic acid in the air upon the temperature of the ground. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science Series 5, 41 (251). 39 pages.  doi.org/10.1080/14786449608620846
  20. Philip Shabecoff, Global Warming Has Begun, Expert Tells Senate, The New York Times, June 24, 1988, Section A, Page 1  

Further Exploration (in order of relevance to this article)

Wildfires and Climate Change
The Physics of Megafires
  • See this for a nice review of how topography affects wildfire growth.  
  • Lecture by Neil Lareau discussing the physics of pyrcocumulonimbus clouds: "Radar and Lidar Observations of wildfire plume dynamics" (Nov 19, 2020)
  • NOVA: Inside the Megafire: Excerpt
    • The whole documentary is worth watching to understand how the physics of megafires and why they are fundamentally changing but the segment from 22:20-27:30 min is especially relevant. 

GIS + Wildfire Mapping
  • 2020 fire perimeter shapefiles are here

California Wildfires (2020 and in general)
Colorado Wildfires​ (2020 and in general)
  • Boulder County Wildfire Protection Plan
    • Every year Boulder conducts a small number of  prescribed burns in the Flatirons.  I wish they did more.  
    • ​The 2011 "Areas of Concern Map" on page 74 of the plan is eye-popping.  Time for an update?
  • Boulder County Story Map about historical wildfires in the region.
    • Note that the 2003 Overland fire was also driven by an approaching cold front (October 29, 2003).
  • Mason Jenkins has a very nice ArcGis story map about the 2020 Wildfires and the 2002 Hayman Fire.





























The Mountain Pine Beetle
Boulder Weather Data: 
How sure are climate scientists ?
  • If you are unsure of how to evaluate uncertainty in various scientific claims, especially those about climate change, I *highly* recommend this short film by Neil Halloran called "Degrees of Uncertainty". 

2020 Hurricane Season
Migrations and other Global Effects of Climate Change
A Historical View of Climate Change
Modern Climate Science
  • Raymond Pierrehumbert, The Principles of Planetary Climate, Cambridge University Press (2010)
    • A advanced undergraduate and beginning graduate level textbook about climate physics on earth and other planets
  • www.realclimate.org -- A blog maintained by many of the leading experts on climate change including Gavin Schmidt, Michael Mann, Raymond Pierrehumbert, David Archer, Stefan Rahmstorf and others.  
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