Tom Swetnam

Warming Worries of a Once-Doubtful Climate Scientist Mike Wallace says reality is bad enough. Catastrophe-versus-hoax framing obscures the momentous dangers from unabated greenhouse-gas heating.

Must read to see how a noted Atmospheric Scientist shifted on climate change ...thank you @revkin.bsky.social
revkin.substack.com/p/warming-wo...

Increasing wildfire frequency decreases carbon storage and leads to regeneration failure in Alaskan boreal forests - Fire Ecology Background The increasing size, severity, and frequency of wildfires is one of the most rapid ways climate warming could alter the structure and function of high-latitude ecosystems. Historically, boreal forests in western North America had fire return intervals (FRI) of 70–130 years, but shortened FRIs are becoming increasingly common under extreme weather conditions. Here, we quantified pre-fire and post-fire C pools and C losses and assessed post-fire seedling regeneration in long (> 70 years), intermediate (30–70 years), and short (< 30 years) FRIs, and triple (three fires in < 70 years) burns. As boreal forests store a significant portion of the global terrestrial carbon (C) pool, understanding the impacts of shortened FRIs on these ecosystems is critical for predicting the global C balance and feedbacks to climate. Results Using a spatially extensive dataset of 555 plots from 31 separate fires in Interior Alaska, our study demonstrates that shortened FRIs decrease the C storage capacity of boreal forests through loss of legacy C and regeneration failure. Total wildfire C emissions were similar among FRI classes, ranging from 2.5 to 3.5 kg C m−2. However, shortened FRIs lost proportionally more of their pre-fire C pools, resulting in substantially lower post-fire C pools than long FRIs. Shortened FRIs also resulted in the combustion of legacy C, defined as C that escaped combustion in one or more previous fires. We found that post-fire successional trajectories were impacted by FRI, with ~ 65% of short FRIs and triple burns experiencing regeneration failure. Conclusions Our study highlights the structural and functional vulnerability of boreal forests to increasing fire frequency. Shortened FRIs and the combustion of legacy C can shift boreal ecosystems from a net C sink or neutral to a net C source to the atmosphere and increase the risk of transitions to non-forested states. These changes could have profound implications for the boreal C-climate feedback and underscore the need for adaptive management strategies that prioritize the structural and functional resilience of boreal forest ecosystems to expected increases in fire frequency.

Increasing wildfire frequency decreases carbon storage and leads to regeneration failure in Alaskan boreal forests fireecology.springeropen.com/articles/10....

Although most trees in western USA conifer forests are killed by high intensity crown fires, most California coast redwoods survive by resprouting (photo by Jon Keeley, 2 years after the CZU Fire in Big Basin State Park).

🔥🌱 From the #AJB Special Issue: “Understanding novel #fire regimes using plant trait‐based approaches" 🌱🔥

#Sequoia and Sequoiadendron: Two paleoendemic megatrees with markedly different adaptive responses to recent high-severity fires

By Jon Keeley & @jgpausas.bsky.social

doi.org/10.1002/ajb2...

Climate-linked escalation of societally disastrous wildfires Climate change and land mismanagement are creating increasingly fire-prone built and natural environments. However, despite worsening fire seasons, evidence is lacking globally for trends in socially ...

Published today: our new paper showing a 44-year trend of increasing global wildfire disasters (fatalities and economic losses) due to climate change-induced extreme weather. www.science.org/doi/10.1126/...

Despite congressional threat, National Academies releases new climate report Things have changed since 2009: We’re more certain about the problems.

National Academies of Science panel finds that: The EPA was right in 2009 (when it found that climate change driven by society’s emissions of greenhouse gases are endangering human health & lives), and that everything we've learned since has only made it more right.

arstechnica.com/science/2025...

Impact of current and warmer climate conditions on snow cover loss in burned forests Wildfires are causing earlier snowmelt across the western US, and this effect would be exacerbated with projected warmer winters.

New Science Advances paper on the feedback loop between loss of snow feeding more wildfire, and wildfire resulting in earlier snowmelt. As to latter, in snow obs, under average conditions, snow melts earlier during 1st-yr postfire in 99%(!) of western snow zones.

www.science.org/doi/10.1126/...

Changing Climate, Changing Fire: Understanding Ecosystem-Specific Fire–Climate Dynamics in Arizona and New Mexico journals.ametsoc.org/view/journal...

What NIJ Research Tells Us About Domestic Terrorism Militant, nationalistic, white supremacist violent extremism has increased in the United States. In fact, the number of far-right attacks continues to outpace all other types of terrorism and domestic...

This is an archived government report that found that “Since 1990, far-right extremists have committed far more ideologically motivated homicides than far-left or radical Islamist extremists.”

It existed yesterday and is gone today.

A Eulogy for Teakettle Justice William O. Douglas, in his dissenting opinion of the Supreme Court’s decision in Sierra Club v. Morton, said “Contemporary public concern for protecting nature’s ecological equilibrium...

The Garnet Fire has burned through a place I have worked since 2002. A place I hold dear. We knew this wasn't a matter of if, but when. Unfortunately the leadership on the Sierra National Forest didn't have the same urgency that we did. My eulogy for Teakettle.
www.hurteaulab.org/blog/a-eulog...

The legacy lost when Forest Service offices shut down After 117 years of operation, the U.S. Forest Service’s Southwest Regional Office in Albuquerque is closing by order of the secretary of agriculture. Since 1908, this office has directed the

Our op-ed in the Santa Fe New Mexican today highlights the potential losses from closure of the nine US Forest Service Regional Offices, namely local leadership knowledge and capacity, experienced people, and priceless documentary records: www.santafenewmexican.com/opinion/my_v...

Figure S4. Percent of sites recording fire that burned in 1652 (a), 1748 (b), 1800 (c), 1855 (d), 2011 (e), and 2021 (f). These correspond to the years in which the highest average percent of sites burned within hexels in the historical (1600-1880; a-d) and contemporary (1984-2022; e-f) time periods (refer to Fig. 2b). Historically, fires in particularly active fire years were generally widespread across the study area. In 2011, however, fire was more localized and concentrated in the south-central United States (e), and in 2021, most fire occurred in the Pacific Northwest, with a few additional hexels recording fire elsewhere (f). Overall, fire in particularly active historical fire years was spatially more widespread and ubiquitous compared to contemporary active fire years

According to supplemental figure 4 of this paper (www.nature.com/articles/s41...), here's the 1748 pattern (top-right panel). 🔥🧪🌍

Well, this is a stimulating review! Some nice kudos, and a few critiques that are partly accurate, I’d say. I especially like the comparison with “psychedelic wanderings” of hippies! And I agree, it is a “modest intervention” in scholarly history of the Southwest.

One more thing:
The fire severity data used to conduct this study can be downloaded here. This is a gridded dataset of satellite-derived fire severity and pre-fire NDVI for all fires in the western US that burned from 1985 to 2022.
🔥🌍🧪 #OpenScience

The merchants of doubt are back But this time, it's the U.S. government pushing doubt

On The Climate Brink, I write about the DOE report and our response.

A 1940 Western Apache (Ndee) farm site with two wickiups in a ponderosa pine forest. CREDIT: Lee Russell/Library of Congress

Tree-ring fire records from 649 pine trees in central and eastern Arizona show that fires occurred more often in the territory of the Western Apache, or Ndee, than in other regions between 1600–1870, suggesting a culturally controlled fire regime. In PNAS: www.pnas.org/doi/10.1073/...

What to Read: The Jemez Mountains by Thomas W. Swetnam Thomas Swetnam's new book explores the Jemez Mountains through memory, science, and story.

New Mexico Magazine recommends THE JEMEZ MOUNTAINS by @firescar.bsky.social!

Thread. Yet another avatar for Dragon Bravo - burning an isolated mesa in the Canyon, this time The Dragon itself (one of the Canyon's most apt placenames).

The massive Grand Canyon fire is burning out of control The Trump administration's US Forest Service staffing cuts may have hampered the agency's ability to respond.

The massive Grand Canyon fire is burning out of control

Anthropogenic warming drives earlier wildfire season onset in California Anthropogenic warming accelerates wildfire season onset in California.

A open-access paper on how wildfire season starts earlier in California thanks to the higher temperatures that fossil fuel burning have caused, and I wasn't able to find one of the authors on here. Kind of the first in a while.

www.science.org/doi/10.1126/...

Tree rings reveal persistent Western Apache (Ndee) fire stewardship and niche construction in the American Southwest | PNAS Identifying the influence of low-density Indigenous populations in paleofire records has been methodologically challenging. In the Southwest United...

Fine work that both extends our knowledge of the past and has implications for today. Ndee (Western Apache) land management did a remarkable job controlling forest fires, even in drought-heavy eras like ours. It defies belief to think today's fire-torn SW has nothing to learn from those guys.

1/New Open Access paper in PNAS with an outstanding team of collaborators:
Tree rings reveal persistent Western Apache (Ndee) fire stewardship and niche construction in the American Southwest.
www.pnas.org/doi/10.1073/...

Interesting paper. Odd though that they don’t cite the ur-paper on tree “Longevity Under Adversity” Schulman’s classic on aridity and ancient trees in Science https://www.jstor.org/stable/1682970

Reconsidering space-for-time substitution in climate change ecology - Nature Climate Change Ecologists often leverage patterns observed across spatial climate gradients to predict the impacts of climate change (space-for-time substitution). We highlight evidence that this can be misleading n...

New paper out on the dangers of using patterns across spatial climate gradients to predict what will happen with changing climate. That includes species distribution modeling. Space-for-time substitution can be misleading in sign, not just the magnitude of effects.
www.nature.com/articles/s41...

Every time I open LinkedIn, someone from a science agency shares an unplanned (forced) early retirement or RIF. Lately it’s NASA & EPA. In spring, NOAA. I think people have no idea how deep this loss really is. I don’t know what rebuilding federal science looks like, but it won’t be simple or quick.

Generally it was large sheep herds and other livestock that first caused the cessation of spreading fires in SW forests. We see this in some places with early Spanish livestock grazing, and some areas later after the railroads came. FS had a few rangers putting out fires in the Gila by 1908-10.

The age of consequence: Wildfires in New Mexico | Searchlight New Mexico Drought and climate change will spark catastrophic fires unless forests are better managed — starting now.

I don't know enough to comment about the Laguna Fire yet, except that it seemed to be low severity in many places. Here is an article from a few years ago. mostly about the problem of high severity fires in NM, but also the need for managed fire: searchlightnm.org/the-age-of-c...

References and further reading about Gila fire history and ecology studies: 18/18

However, initial burns in parts of this landscape have exacted a cost in tree mortality in some large patches. Where can the Gila exemplar be replicated? Undoubtedly, a different tack including other management strategies is needed in smaller Wilderness areas and the Wildland Urban Interface.17/18

In sum, the Gila is an exemplar of a “restored” high-frequency surface fire regime. Wildfires burning today, even during drought, are generally constrained in severity by previous burns. This photo is from 2013 on Iron Creek Mesa, with previous burns in 1985, 2003, 2012, and now again in 2025. 16/18

Approximate same view as previous image from an airplane in about 2000, prior to managed and wildfires burning large canopy holes on the ponderosa pine/mixed conifer mesas, and up over the spruce-fir forests on the high ridges and peaks of the Mogollons. 15/18