Increase in U.S. Wildfires Due to Climate Change

Pro: Many media outlets are blaming “climate change” for the increased wildfires in the western United States.

For example, this article from Vox: The West is burning. Climate change is making it worse.

In the article they say:

Climate change is supercharging wildfire season

Like most of the West, drought conditions in California and Oregon have fueled the Bootleg and Dixie Fires, resulting in a fire season that is far worse than usual, far earlier.

According to the US Drought Monitor, major swaths of Washington, Oregon, California, Montana, Idaho, Nevada, Utah, Arizona, and New Mexico are all in the midst of a drought, as are other parts of the US.

More than 95 percent of that region is experiencing at least “moderate” drought conditions, according to a map produced by the US Drought Monitor, and about 65 percent is facing “extreme” conditions.

…

Scientists say that [the current drought] is part of a megadrought — a decades-long dry spell, punctuated by severe droughts. This current megadrought began around 2000, and the majority of the land in the West has been at some level of drought ever since.

And this striking drought bears the fingerprints of climate change. Using tree ring data, a study published in Science in April 2020 found that “anthropogenic warming was critical for placing 2000–2018 on a trajectory consistent with the most severe past megadroughts,” and that megadrought has extended to today.

NASA claims that climate is affecting wildfire:2

Natasha Stavros is an applied science system engineer at NASA’s Jet Propulsion Laboratory in Southern California who studies wildfires. She says that not only is the U.S. West experiencing more frequent wildfires, but they’re also happening at the same time, putting a strain on resources. They’re also bigger, more severe, and faster than ever before, and more destructive, with 15 of the 20 most destructive wildfires in California history occurring within the past decade.

CON: Wildfires are far less frequent and severe than was the case throughout the first half of the 20th century.

  • Occasional upticks in current wildfire activity still result in far less land burnt than was the case throughout the 20th century. Even the worst recent wildfire years burned only 1/5th to 1/2 as much land as typical wildfire years during the early 20th century.
  • Drought is the key climate factor for wildfires. The United States in recent decades is benefiting from strikingly small amounts of drought.
  • Data showing more wildfire in the past was disappeared by an official fire agency because it doesn’t illustrate more fires in the present.
  • Fuel loads in the Western United States have been increasing since 1990, when The Spotted Owl was listed as endangered, shutting down most of the logging industry and most forest management practices.
  • Recent large fires in the west, such as the Camp Fire and the Dixie Fire have been ignited by man-made ignition sources. Rather than man-made climate change.

Wildfires, especially in arid parts of the United States, have always been a natural part of the environment and likely always will. Global warming did not create wildfires. In fact, wildfires have become less frequent and less severe in recent decades. A contributing factor has been less drought in the United States during recent decades. In fact, data displayed by the National Atmospheric and Oceanic Administration, NOAA, show no discernable trend for increased drought in the United States in over 125 years.3

The U.S. National Interagency Fire Center (NIFC) reports data on U.S. wildfires back as far as 1926. The NIFC data show the numbers of acres burned is far less now than it was throughout the early 20th century, 100 years of global warming ago. See Figure 1, below. Current acres burned run about 1/4th to 1/5th of the record values which occurred in the 1930s. At that time, the peak wildfire burn was over 52 million acres. In the decade since 2010, the peaks have been 10 million acres or less.

Figure 1: All available wildfire acreage burned by year in the United States, 1926 to 2019. Data from NIFC prior to disappearance in 2021. Graph by Anthony Watts

Climate proponents sometimes cite a very small upwards trend since 1983 to suggest that climate change has been making wildfires worse in the USA. However, that is a very minor trend compared to the complete picture of data.

In fact, they have been so insistent that there is an upwards trend in U.S. wildfires, in March 2021, they convinced the NIFC to remove wildfire data prior to 1983, saying that data was now “unreliable”, even though it had been used in peer reviewed science publications for decades.

With the Biden administration now in control of NIFC, the agency says,4

“Prior to 1983, the federal wildland fire agencies did not track official wildfire data using current reporting processes. As a result, there is no official data prior to 1983 posted on this site.”

By disappearing all data prior to 1983, which just happens to be the lowest point in the data set for the number of fires, NIFC data now show a positive slope of worsening wildfire aligning with increased global temperature. This truncated data set is perfect for claiming “climate change is making wildfire worse,” but flawed because it lacks the context of the full data set. See figure 2 below for a before-and-after comparison of what the NIFC data look like when you plot it.

Figure 2: A comparison of before and after NIFC removed wildfire data prior to 1983. Note that 1983 is the lowest point in the entire record, ensuring a positive upwards trend from that point forward.

The NIFC decision to declare data prior to 1983 “unreliable” and removing it is not just hiding important fire history, but choosing a data starting point that is the lowest in the entire record to ensure that an upwards trend exists from that point. That is too coincidental to be anything but cherry-picking for a desired result.5

In fact, NIFC and/or climate activists were able to convince the Wayback Machine to remove all traces of the website wildfire data, even though it existed there before.6 That’s no coincidence.

Further, Drought for much of the west is normal. A study of tree ring data shows as droughts lasting as long as 200 years have occurred in the Western United States as seen in Figure 3.7

Figure 3: Tree ring drought reconstruction data from Cook et al., 20077. Graph by Karl Kahler, Bay Area News Group and annotated by Anthony Watts.

In another study, the author says:8

“[T]he USA has been in a state of drought over much of the West for about 10 years now. While severe, this turn of the century drought has not yet clearly exceeded the severity of two exceptional droughts in the 20th century. So while the coincidence between the turn of the century drought and projected drying in the Southwest is cause for concern, it is premature to claim that the [climate] model projections are correct.

At the same time, great new insights into past drought variability over North America have been made through the development of the North American Drought Atlas from tree rings. Analyses of this drought atlas have revealed past megadroughts of unprecedented duration in the West, largely in the Medieval period about 1000 years ago.“

Clearly, drought is normal and natural for the Western United States. Recent claims of it being driven by “man-made climate change” related to recent increases in atmospheric CO2 warming the planet are unsupported by science.

Finally, data shows that the single biggest impact on wildfires in the U.S. has been an environmental ruling that essentially stopped almost all logging and forest management in the Western United States.

The U.S. Fish and Wildlife Service listed the northern spotted owl as threatened under the Endangered Species Act in 1990.9 After the owl was listed under the Endangered Species Act, U.S. officials halted logging on millions of acres of old-growth forests on federal lands to protect the bird’s habitat. Simultaneously, the U.S. Forest Service shut down most wildfire prevention projects that had been administered to federal forest lands in the past.

The result has been that fuel load has been accumulating since 1990 because forest management in much of the Western United States is non-existent due to protected owl habitat. This is well illustrated using data in Figure 4.

Figure 4. Graph combining data for Federal lands showing acres harvested vs. acres burned, in millions of acres. Data from U.S. Forest Service and the National Interagency Fire Center. Graph by Anthony Watts using that data.

As clearly illustrated in Figure 4, after 1990, timber harvesting plummeted along with forest management. At the same time, as fuel load accumulated due to lack of harvesting and management, the acreage of burned forests increased.

According to the U.S. Forest Service,10

“In the 1970’s, concerns about environmental impacts and conflicting uses escalated, leading to increased lawsuits and additional environmental protection measures. As a result, the Forest Service now operates federal timber sales under some of the most substantial and effective environmental protection policies in the world. In response to the public controversy and a greater understanding of how management actions influence the landscape, today’s timber sale levels have dropped by two-thirds (back to the pre-1950 levels), even though timber demand continues to increase at a rate of about one percent annually.

…

Approximately 73 percent of the 191 million acres of national forests are considered forested. Of that forested land, 35 percent is available for regularly scheduled timber harvest and about ½ of 1 percent of those trees are harvested in any 1 year.“

Source: U.S. Forest Service, About us, Environmental Protection, accessed 9/12/21, https://www.fs.fed.us/forestmanagement/aboutus/today.shtml

References:

  1. The West is burning. Climate change is making it worse., Vox, Cameron Peters, https://www.vox.com/2021/7/25/22592004/wildfires-climate-change-reconciliation-bill
  2. The Climate Connections of a Record Fire Year in the U.S. West, Alan Buis, NASA’s Jet Propulsion Laboratory, https://climate.nasa.gov/blog/3066/the-climate-connections-of-a-record-fire-year-in-the-us-west/
  3. Drought Graph, U.S. Percentage Areas, NOAA National Climatic Data Center, https://www.ncdc.noaa.gov/temp-and-precip/uspa/wet-dry/0
  4. Total wildfire acreage burned by year in the United States, 1983 to 2020. Data from https://www.nifc.gov/fireInfo/fireInfo_stats_totalFires.html
  5. The definition of cherry picking, Wikipedia, accessed 8/15/21, https://en.wikipedia.org/wiki/Cherry_picking
  6. The Internet Wayback Machine, showing logged copies of the https://www.nifc.gov/fire-information/statistics/wildfires webpage, accessed 8/15/2021, https://web.archive.org/web/*/https://www.nifc.gov/fire-information/statistics/wildfires
  7. North American drought: Reconstructions, causes, and consequences, Cook et al., Earth-Science Reviews 81 (2007) 93–134, accessed 9/10/21, http://ocp.ldeo.columbia.edu/res/div/ocp/pub/cook/Cook_etal_2007_ESR.pdf
  8. Megadroughts in North America: placing IPCC projections of hydroclimatic change in a long-term palaeoclimate context, Cook et al., Journal of Quaternary Science, May 2009, accessed 9/11/21, http://water.columbia.edu/files/2011/11/Seager2009Megadroughts.pdf
  9. U.S. Fish and Wildlife Service, Northern Spotted Owl, accessed 9/12/21, https://www.fws.gov/oregonfwo/articles.cfm?id=149489595
  10. U.S. Forest Service, About us, Environmental Protection, accessed 9/12/21, https://www.fs.fed.us/forestmanagement/aboutus/today.shtml