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:
- California: A Canary in the Coal Mine
- Sept 7-8, 2020: Once-in-a-Century Weather Across the US Mountain West
- The Rest of Colorado's Wildfire Season
- The Future of Colorado?
- Our Place in History
- What to do about it?
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 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).
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.
2. Sept 7-8, 2020: Once-in-a-Century Weather Across the US Mountain West
The Pacific Northwest
Colorado: The Cameron Peak Fire
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%.
3. The Rest of Colorado’s Wildfire Season
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.
A resilient Cameron Peak Fire...
The East Troublesome Fire
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.)
Colorado is under the worst Fire siege in recent history. This is a reconstruction from Aug 13th till today from VIIRS (last seconds are for #EastTroublesomeFire). Impossible terrain, long drought, heavy fuels, and in recent days, terrible weather. Hopefully, everybody stays safe pic.twitter.com/kvLNLVnDTk— Joaquin Ramirez (@jramireztsyl) October 23, 2020
The Calwood Fire
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.
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.
4. The Future of Colorado?
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.
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?
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.
5. Our Place in History
Human civilization is now in completely uncharted territory.
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).
6. What to do about it?
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?
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.
- California August - October temperatures, 1895-2020 (Daniel Swain, NOAA)
- California wildfire intensity correlates with warm + dry weather (Berkeley Earth)
- GOES-17 imagery from CIRA/RAMBB of California wildfires on Sept 05, 2020 (Wikipedia)
- GOES-17 imagery from CIRA/RAMBB of Northern California Fire complexes (mixed dates). (Dakota Smith, @Weatherdak)
- GOES-17 imagery from CIRA/RAMBB of the Creek Fire on Sept 05, 2020. (Dakota Smith, @Weatherdak)
- GOES-17 imagery from CIRA/RAMBB of lightning strikes produced by the Creek Fire on Sept 05, 2020 (Dakota Smith, @Weatherdak)
- GOES-17 imagery from CIRA/RAMBB of wildfire smoke and approaching cold front on Sept 07, 2020 (Daniel Swain, @Weather_West)
- Daniel Swain's explanatory thread is definitely worth reading.
- GOES-17 imagery from CIRA/RAMBB of explosive wind-driven growth of Cold Springs Fire on Sept 07, 2020 (Dakota Smith, @Weatherdak)
- GOES-17 imagery from before and after the 2020 Oregon wildfires (Dakota Smith, @Weatherdak)
- "Hot, Cold & Snowy: A look back at the record-shattering wild week of "summer" weather." BoulderCAST blog post. t
- Aerial Photo of the Cameron Peak Fire by Jason Bloch (@JasonBloch)
- ArcGis story map of the Cameron Peak Fire produced by the National Interagency Fire Center
- NWS Boulder
- 5 minute time-lapse of vortices in the Calwood Fire smoke plume by Fox 31 Meteorologist Brooks Garner (@brooksweather)
- 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
- Glaciers, Climate Change, and Sea-Level Rise, NASA Earth Observatory
- 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
- 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:
- 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
- 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
- NASA GISS Surface Temperature Analysis, (GISSTEMP v4) https://data.giss.nasa.gov/gistemp/
- Intergovernmental Panel on Climate Change (IPCC) Special Report: Global Warming of 1.5 ºC, Chapter 1, page 57.
- 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
- 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)
- Smith A.J.P et al, Climate Change Increases the Risk of Wildfires Science Brief News, Sept 24 2020
- PBS Newshour Segment from Sept 14, 2020: "How climate change 'exacerbates' wildfires in the American West"
- Jeff Berardelli, Wildfires and weather extremes: It's not coincidence, it's climate change, CBS News, Sept 17, 2020
- Jeff Berardelli explains the Sept 07 winter storm (CBS News)
- Factcheck: How Global Warming Has Increased US Wildfires, Carbon Brief, August 9, 2018
- The excellent article debunks many myths, even some that sound quite reasonable at first introduction.
- Climate Toolbox: Fire Danger Mapper-Past
- Wildfires and Insurance: www.iii.org/fact-statistic/facts-statistics-wildfires
- Insurance companies are already tacitly acknowledging that climate change is fundamentally changing wildfires.
- Climate Change Indicators: Wildfires: Environmental Protection Agency
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)
- Summary of the 2020 fire season on the West Coast (incredible graphics): NYT Article
- Photos from AFP news of orange skies in SF
- When is peak California fire season?: www.frontlinewildfire.com/when-california-fire-season/
- Frontline Documentary on the 2018 Camp Fire in Paradise CA: Fire in Paradise
Colorado Wildfires (2020 and in general)
- NYT article on Cameron Peak Fire
- 1996 Buffalo Creek Fire USGS Hydro report: pubs.usgs.gov/wri/2001/4122/report.pdf
- Boulder County Wildfire Protection Plan
- 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.
- Jesse A. Logan, James A. Powell, Ghost Forests, Global Warming, and the Mountain Pine Beetle (Coleoptera: Scolytidae), American Entomologist, Volume 47, Issue 3, Fall 2001, Pages 160–173, https://doi.org/10.1093/ae/47.3.160
- NPS Beetle Kill: www.nps.gov/romo/learn/nature/mtn_pine_beetle_background.htm
- Spruce Kill, San Juans: durangoherald.com/articles/312513#slide=0
Boulder Weather Data:
- Boulder Climate Data (Temp/precip): https://psl.noaa.gov/boulder/data/boulderdaily.complete.txt
- Wind speed: midcdmz.nrel.gov/apps/daily.pl?site=NWTC&start=20010824&yr=2021&mo=1&dy=1
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
- Record Breaking 2020 Hurricane Season (CBS News)
Migrations and other Global Effects of Climate Change
- A Quarter of Humanity Faces Looming Water Crises NYT Article
- The Great Climate Migration, NYT Magazine Article
- Al Shaw and Abrahm Lustgarten New Climate Maps Show a Transformed United States Pro Publica, Sept 15, 2020
- How Climate Migration will Reshape America
A Historical View of Climate Change
- David Archer and Raymond Pierrehumbert, The Warming Papers: The Scientific Foundation for the Climate Change Forecast, Wiley-Blackwell (2011).
- Spencer Weart, The Discovery of Global Warming, Revised and Expanded Edition, Harvard University Press (2008)
- TED Talk by Jim Hansen (lots of historical context, well worth your time): video
- Modern climate scientists talking about the accuracy of James Hansen's 1988 testimony: video
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.