Tom Swetnam

but we gotta turn over public lands to private interests because they’re bEtTeR aT mAnAgEmEnT, right?

Nothing to see here; just the division that funds (or not) all of us in the environmental sciences, including atmosphere, ocean, ice, Earth, climate, hydrology, whatever.

Last, this study demonstrates (again) that fire scar networks in Southwestern ponderosa pine dominant fire regimes can provide highly reliable and accurate estimates of fire extent and related fire regime metrics (e.g., fire frequency, fire rotation, etc.). 6/6

New methods provide a 300‐year perspective on modern area burned in two wilderness areas of the southwest United States Climate change, expanding human ignitions, and increased fuels from fire exclusion are driving increases in area burned and fire severity in dry conifer forests of the western United States. Increasi...

This work demonstrates the potential to quantify past areas burned at regional to continental scales. This opens the door for quantifying long term and fine to broad-scale fire effects on forests and carbon dynamics. 5/6

Open access link, again: esajournals.onlinelibrary.wiley.com/doi/10.1002/...

All models performed very well, demonstrating that even relatively low spatial density fire scar networks can be used to quantitatively and accurately estimate area burned over time. Prescribed fire programs in these two wilderness areas have effectively restored the pre-1900 fire regimes. 4/6

This is a new and important advance in dendrochronology, because, to my knowledge, this is the first time a spatial ecological process has been reconstructed using tree-ring event networks at these scales, resolutions, and with very high levels of statistical accuracy (r-squared = 0.88 to 0.98). 3/6

Spatial networks of fire scarred trees and twentieth-century burned area observations in the form of mapped fire perimeters (fire atlases) were used to calibrate and validate reconstructions of area burned in absolute values, that is hectares burned per year, extending back to the early 1700s. 2/6

My colleagues Calvin Farris (NPS) and Ellis Margolis (USGS) led a landmark study in paleofire reconstruction. In addition to showing that fire management can restore past fire regimes, the demonstrated methods are a first in dendrochronology. 1/6 esajournals.onlinelibrary.wiley.com/doi/10.1002/...

The Jemez Mountains A Cultural and Natural History by Thomas W. Swetnam Winner of the 2025 Southwest Book Award from the Border Regional Library Association

CONGRATULATIONS to Thomas W. Swetnam (@firescar.bsky.social), author of The Jemez Mountains: A Cultural and Natural History!

WINNER of the 2025
Southwest Book Award

from the Border Regional Library Association

📚💙 #NewMexico

Map from NOAA Climate at a Glance depicting the relative rank of Nov-Dec 2025 temperatures on a county-by-county basis. Most Western U.S. counties experienced their warmest Nov-Dec on record, as depicted by all locations dark red in color on the map.

Well, it's now official (per NOAA): Dec (and Nov-Dec) 2025 were the warmest such periods on record for Western U.S. (and also for most individual Western states). It has been an extraordinarily sustained period of winter warmth, and this eerily balmy winter continues into Jan.

Map (from NRCS) showing current snow water equivalent (SWE) anomalies at numerous points throughout the Western United States. Nearly all points are well below average--with many under 50% of usual mid-Jan values--except in the Central/Southern Sierra and across portions of the Northern Rockies (where values are near average, or even locally above).

Snowpack across much of West was at record or near-record low levels for most of Dec. Despite recent local recovery--esp. in central/southern Sierra in California--it remains extremely low most everywhere else. Record low snowpack may return by later in Jan w/this pattern.

The continued destruction of science by the US administration is beyond appalling and disgusting. This includes the withdrawal of the the US from IAI, Inter-American Institute for Global Change Research. This is a massive mistake and loss for all.

In December I received a deeply meaningful recognition for my research from AFE, especially to cap off the unhinged year that was 2025. I dedicate this award to all scientists - especially my fellow feds - who have been vilified and whose work has not been valued.

@afe-fireecology.bsky.social

New in @globalchangebio.bsky.social: thoughts from me & Jilmarie Stephens on recent study confirming that vegetation accumulation-to-desiccation cycles induced by wet-to-dry climate transitions increase wildfire severity in California's non-forested biomes. onlinelibrary.wiley....

Threatening to dismantle NCAR, our premier weather and climate research institute (apparently) because Colorado refuses to pardon someone accused of tampering with voting machines is a sad example of our current kakistocracy in action… www.nytimes.com/2025...

Unbelievable. This would be a terrible blow to American science, writ large. It would decimate not only climate research, but also the kind of weather, wildfire, and disaster research that has underpinned half a century of progress in prediction, early warning, and increased resilience.

A deeply dangerous — and blatantly retaliatory action against Colorado — by the Trump administration.

NCAR is one of the most renowned scientific facilities in the WORLD — where scientists perform cutting-edge research everyday.

We will fight this reckless directive with every legal tool we have.

NCAR is quite literally our global mothership.

Everyone who works in climate and weather has passed through its doors and benefited from its incredible resources.

Dismantling NCAR is like taking a sledgehammer to the keystone holding up our scientific understanding of the planet.

Unbelievable.

As we all watch Ken Burn’s American Revolution on Public Broadcasting Service (PBS) this evening, remember that federal funding for this public programming has been cut by a president who aspires to be like the king patriots separated from nearly 250 years ago.

Prohibited activities include advising Chinese graduate students. For reference, a recent Georgetown report estimated 16% of STEM graduate students in the US are Chinese nationals.

This would take out entire fields at the knees, which is perhaps the point.

Final version now available #AmJBot @botsocamerica.bsky.social

Sequoia & Sequoiadendron: Two paleoendemic megatrees with different adaptive responses to high-severity fires
bsapubs.onlinelibrary.wiley.com/doi/10.1002/...

Plants are not adapted to fire, but to fire regimes
🧪🌍🔥🌳🌿🪴 #ecoevo #wildfire

Resolution and Frequency‐Dependent Climate Signals in an Arctic Tree‐Ring Temperature Reconstruction of the Last Millennium Tree-ring density measurement resolution affects low-frequency trends in temperature reconstructions High-resolution anatomical maximum latewood density has stronger correlations with instrumenta...

Dr. Julie Edwards (@julieedtree.bsky.social) leads a new paper showing that high-resolution cellular-scale measurements (Quantitative Wood Anatomy) yield better temperature signals in Alaskan tree rings than even conventional MXD across all frequencies agupubs.onlinelibrary.wiley.com/doi/10.1029/...

An Asteroid Impact May Have Led to Flooding near the Grand Canyon - Eos There’s remarkable synchronicity between the timing of a paleolake in what is today Grand Canyon National Park and the formation of nearby Barringer Meteorite Crater.

When it comes to famous holes in the ground, northern Arizona has two: the #GrandCanyon and #MeteorCrater. New research suggests that these famous depressions might, in fact, be linked.

Photo of a ski resort with smoke rising above from the fire on the backside of the mountain. In the distance, a retardant drop is being made on a ridge.

Back in the day, I was working a fire near a fancy ski resort. This was when $30 million homes were still unfathomable to me. This guy, who kept bragging that he had the President's personal phone number, came up and said he was going to write a check to pay for all the firefighter meals. 1/

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/...