Tag: Tree Rings

“Bomb Carbon” from 1960s Tree Rings Reveals Biochar Stays Locked in Soil for Centuries

Researchers at the Swedish University of Agricultural Sciences (SLU) developed a method using “bomb carbon” (elevated radiocarbon- 14 from 1960s atmospheric nuclear tests, preserved in tree rings) in wood shavings to track how stable biochar is when added to soil.

Close-up of a tree stump with a spotlight on 'Bomb Carbon 14C', showing bark and soil. In the background, a field of crops grows under a blue sky with clouds. The image suggests themes of carbon sequestration and environmental impact.
AI generated by Grok

Researchers at the Swedish University of Agricultural Sciences (SLU) developed a method using “bomb carbon” (elevated radiocarbon- 14 from 1960s atmospheric nuclear tests, preserved in tree rings) in wood shavings to track how stable biochar is when added to soil.

Biochar is a charcoal- like material produced by heating biomass (here, wood) in low- oxygen conditions (pyrolysis). It is of interest for improving soil properties and as a potential long-t erm carbon sink to help mitigate climate change, with global estimates suggesting it could sequester carbon equivalent to roughly 6- 16% of annual anthropogenic CO₂ emissions. A key uncertainty has been how quickly biochar mineralizes (breaks down into CO₂) in soil versus remaining stable for decades or centuries, and how to distinguish its contribution from native soil organic matter.

The method

Atmospheric nuclear testing in the 1950s- 1960s roughly doubled atmospheric ¹⁴C levels, peaking around the mid-1960s. Tree rings from 1964-1967 therefore contain elevated “bomb” ¹⁴C. SLU researchers selected mature Norway spruce and Scots pine trunks from a Swedish clear- cut, identified the relevant rings, and used a professional woodturner to carefully remove outer wood and collect the thin, high-¹⁴C layers as shavings. These were pyrolyzed into biochar (tested at highest treatment temperatures of ~400°C and 650°C).

The resulting biochar had enough ¹⁴C enrichment (on average ~61.7 percent modern carbon higher than bulk soil organic matter in one report) to serve as a natural tracer. In a one-year laboratory incubation, they mixed it into soil (at 2% by dry mass), trapped emitted CO₂, and measured its ¹⁴C signature via accelerator mass spectrometry. This allowed them to quantify the share of CO₂ coming from the biochar versus the soil.

Key findings

  • CO₂ from biochar- amended soil showed up to about 10% higher ¹⁴C than controls, confirming a small but measurable contribution from the biochar.
  • Roughly 0.35% of the added biochar carbon converted to CO₂ over one year.
  • This implies high stability: at least half of the buried biochar is projected to remain in the soil after ~200 years (under the study conditions).
  • The method works with mature wood feedstock that resembles commercial biochars, offers higher precision than some natural- abundance ¹³C approaches, and avoids the need for expensive artificial isotopic labeling.

The work was published in Radiocarbon (Li et al., 2026: “Bomb ¹⁴C for tracing biochar mineralization in soil”). It was funded in part by Sweden’s Bio+ program (Swedish Energy Agency). Follow- up research is planned to examine biochar stability under climate- change scenarios in collaboration with researchers in Germany.⁠

This approach provides a practical way to study biochar persistence, its interactions with soil organic matter, and its viability for carbon sequestration without relying solely on short- term incubations or complex lab labeling.

A person using a wood lathe in a workshop, wearing safety glasses and ear protection, with wood shavings flying around.
To obtain wood formed during the years 1964–1967, the researchers engaged professional woodturner and wood artist Åke Landström from Glanshammar. Credit: Harald Cederlund

Bomb 14C for tracing biochar mineralization in soil

This is the open- access research article “Bomb ¹⁴C for tracing biochar mineralization in soil” by Haichao Li, Harald Cederlund, Elias S. Azzi, Cecilia Sundberg, and Erik Karltun (Swedish University of Agricultural Sciences), published online 23 September 2026 in Radiocarbon (Volume 68, Issue 5, pp. 1146- 1154).

It is freely available under a Creative Commons Attribution (CC- BY) licence.

Core contribution

The authors introduce and validate a practical isotopic- tracing method that uses naturally elevated “bomb” radiocarbon (¹⁴C) preserved in tree rings formed during the atmospheric nuclear- test peak (1964- 1967). Biochar made from this wood carries a clear ¹⁴C signature that can be distinguished from soil organic matter (SOM), allowing precise quantification of how much of the CO₂ released from soil comes from the biochar itself.

Methods (summary)

  • Mature Norway spruce and Scots pine trunks (≥70 years old) were collected from a clear- cut near Uppsala, Sweden.
  • Annual rings from 1964- 1967 were identified by counting and carefully isolated by professional woodturning (producing shavings).
  • Biochar was produced by pyrolysis under N₂ at highest treatment temperatures of 400 °C (BC400) and 650 °C (BC650). The feedstock with the highest ¹⁴C enrichment (~172.9 pMC) was selected.
  • Biochars were acid- washed to remove carbonates, ground (<2 mm), and mixed into a loamy- sand agricultural soil (Cambisol, 1.4 % SOC) at a 2 % (w/w) application rate.
  • Soils were incubated for 365 days at ~20.7 °C and 60 % water- holding capacity. Emitted CO₂ was trapped in NaOH and analysed for total C and ¹⁴C (AMS) at multiple time points.
  • An isotope-mixing model calculated the biochar- derived fraction of respired CO₂. Priming effects on native SOC were also quantified.

Key results

  • Biochar was on average 61.7 pMC higher in ¹⁴C than bulk soil organic matter, providing a clear tracer signal.
  • ¹⁴CO₂ from biochar- amended soils was consistently and significantly higher than from controls (p < 0.0001).
  • Early in the incubation (first 2 weeks) 8.3- 11.4 % of mineralized CO₂- C came from biochar; later this fell to 2.3- 7.5 %.
  • After one year, only 0.32 ± 0.02 % (BC400) and 0.35 ± 0.01 % (BC650) of the added biochar carbon had been mineralized. The two pyrolysis temperatures did not differ significantly.
  • BC650 produced a measurable negative priming effect on native soil organic carbon (–129 ± 20 mg CO₂-C kg⁻¹, or ~14.8 % relative to the control); BC400 showed essentially none.

Advantages claimed over other isotopic approaches

  • Higher precision than the natural- abundance ¹³C (C₃/C₄) method for detecting small biochar contributions.
  • Works with mature wood feedstock that closely resembles commercial biochars (unlike many laboratory pulse- labelled materials derived from young seedlings).
  • Relatively low cost and does not require specialised isotope-labelling facilities.
  • Uniform ¹⁴C enrichment because the trees grew continuously under elevated atmospheric ¹⁴C.

Conclusions

The bomb-¹⁴C method is shown to be effective for quantifying biochar mineralisation and its interactions with soil organic matter. It opens practical possibilities for longer- term studies of biochar persistence and carbon-sequestration potential under realistic conditions.

The paper includes supplementary material with additional figures on priming and sensitivity analyses. Funding came in part from the Swedish Energy Agency’s Bio+ programme.

Close-up of a cross-section of a tree trunk showcasing concentric growth rings with a small central hole, against a black background. The growth rings feature a red marking labeled 'S2'.
Log with younger wood turned away. The wood with the highest content of ‘bomb carbon’ is found in the growth rings between the red circles. Credit: Harald Cederlund

Journal: Radiocarbon (Volume 68, Issue 5, pp. 1146–1154)

DOI: 10.1017/rdc.2026.10247

Provided: Swedish University of Agricultural Sciences

Authors: Haichao Li,

Harald Cederlund,

Elias S. Azzi,

Cecilia Sundberg and

Erik Karltun

Abstract

Improving our understanding of biochar carbon (C) stability in soil is crucial given its potential for soil C sequestration. However, challenges with isotopic labeling of biochar restrict our ability to determine its fate in soil. Atmospheric nuclear bomb tests in the 1960s resulted in a 14C spike in tree rings, providing an opportunity to address this challenge. Here, we present a method that utilizes the elevated levels of 14C in wood from tree rings formed between 1964 and 1967 as a tracer to determine the proportion of biochar C in mineralized soil. Biochar was produced using wood from the 14C enriched tree rings as feedstock and thereafter used in a mineralization experiment capturing the emitted CO2. We demonstrate that the bomb 14C-enrichment in the biochar is high enough to differentiate between CO2 originating from either biochar or soil organic matter mineralization. The method can be used to address questions on biochar persistence, its interactions with soil organic matter and research that is needed to explore the potential to use biochar for C sequestration in soils.

How to stop being surprised by extreme weather? Stop making it about climate.

From the Weather is Not Climate unless we say it is department and the University of Reading, comes this press release about an inane study that tries to link tree rings and severe weather, while ignoring warning fatigue.

From Watts Up With That?

By Anthony Watts

From the Weather is Not Climate unless we say it is department and the University of Reading, comes this press release about an inane study that tries to link tree rings and severe weather, while ignoring warning fatigue.

How to stop being surprised by extreme weather – study

Helping communities predict extreme weather events that have never been recorded in modern history is the focus of a new study published in Nature Communications.

A team from the Climate Adaptation Services Foundation, the University of Reading and other international institutions has brought together methods to see beyond the limitations of conventional weather records, which typically only cover the past century.

The study reveals how, for example, nature’s own archives – like tree rings – combined with forgotten historical documents can unlock centuries of climate data that modern instruments have missed.

Lead author Timo Kelder said: “We’ve been limited by thinking extreme weather is only as bad as what we’ve measured since weather stations were invented. But our research shows we can use weather models to look back hundreds or even thousands of years to discover what’s truly possible in our climate system.”

A toolkit for scientists and practitioners

The researchers identified four approaches that together create a more complete picture of possible extreme weather:

● Analysing conventional records

● Studying historical and natural archives like tree rings

● Creating “what-if” scenarios based on past events

● Using climate models to simulate physically possible extremes

Tree rings proved especially valuable, with each ring preserving a year’s worth of climate history. Researchers used these natural time capsules to reconstruct 850 years of drought patterns in northwestern China, revealing extreme events that would have been invisible in modern records.

The team also highlighted forgotten weather extremes by digging through historical archives. They found that June 1846 in Durham, UK was significantly hotter than any modern June temperature. Similarly, September 1774 in Oxford was wetter than any month recorded in the 250 years since.

Adapt, adapt, adapt

The study emphasises that with these methods to anticipate the unseen, communities can better prepare for unprecedented weather. The methods can support three layers of preparation:

● Improved early warning systems

● Upgraded infrastructure

● Transformative social changes to reduce vulnerability

The researchers conclude that by breaking free from the constraints of limited modern records, we can finally stop being surprised by “unprecedented” weather events.

Dorothy Heinrich, co-author at the University of Reading, said : “Unprecedented weather doesn’t just break records—it breaks communities, infrastructure, and lives. When the unimaginable happens, being unprepared is a disaster waiting to unfold. But science can help us to imagine the unimaginable, to uncover these risks, and prepare. Our future depends on how quickly and thoroughly we adapt today.”

Here’s the study if you want to read it: 

How to stop being surprised by unprecedented weather

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Abstract

We see unprecedented weather causing widespread impacts across the world. In this perspective, we provide an overview of methods that help anticipate unprecedented weather hazards that can contribute to stop being surprised. We then discuss disaster management and climate adaptation practices, their gaps, and how the methods to anticipate unprecedented weather may help build resilience. We stimulate thinking about transformative adaptation as a foundation for long-term resilience to unprecedented weather, supported by incremental adaptation through upgrading existing infrastructure, and reactive adaptation through short-term early action and disaster response. Because in the end, we should take responsibility to build resilience rather than being surprised by unprecedented weather.

Wrong, Mainstream Media, Tree Rings Aren’t Reliable Indicators of Past Temperatures

That graph is highly misleading, if not a flat-out fabrication. It suffers from the same sort of issues in Mann’s original “hockey stick” graph, such as the fact that tree ring data from other trees show no such trend. We know from other studies that the Roman Warm Period (from 1–250 AD) and the Medieval Warm Period (950 to c. 1250 AD) existed, but they have been erased from this graph presented to the public as accurately representing past temperatures, when it is actually dishonest fiction based on a biased analysis of selected proxy data.

From ClimateRealism

By Anthony Watts

Dozens of media outlets such as ABC News, The BBC, The New York Times, and many more, hyped a study that claims summer temperatures in 2023 were unprecedented over the past 2000 years. This claim, in fact, can’t be verified by tree ring data, which isn’t that precise. Researchers are falsely assuming tree rings are reliable temperature indicators when in fact tree rings can indicate a multitude of different conditions, not just temperature.

Further, the study, Esper, J. et al., Nature, 2024, is using an old trick, pioneered by Michael Mann, Ph.D. in his controversial hockey stick graph, where estimated temperatures from select tree rings and other proxies far into the past are grafted onto more reliable temperatures, measured in the present, and presented as one unified dataset, when in fact they are radically different.

For example, the BBC’s article about the study presented this graph, which is highly reminiscent of Mann’s original “hockey stick” graph.

That graph is highly misleading, if not a flat-out fabrication. It suffers from the same sort of issues in Mann’s original “hockey stick” graph, such as the fact that tree ring data from other trees show no such trend. We know from other studies that the Roman Warm Period (from 1–250 AD) and the Medieval Warm Period (950 to c. 1250 AD) existed, but they have been erased from this graph presented to the public as accurately representing past temperatures, when it is actually dishonest fiction based on a biased analysis of selected proxy data.

The fact that these well-known, documented, and scientifically certified climate events have been removed from the graph touted by the media indicate that this is more likely propaganda in pursuit of a political goal, rather than a scientific search for understanding based on honest use of the scientific method.

Another issue with the study is the well-known fact that annual tree ring growth is not tied solely to temperatures, much less the made up metric of “global average temperature,” as Liebig’s law of the minimum explains. Often simply called Liebig’s law, or the law of the minimum, is a principle developed in agricultural science by Carl Sprengel (1840) and later popularized by Justus von Liebig. It states that growth is dictated not by total resources available, but by the scarcest resource (limiting factor).

In other words, plant growth factors from year to year such as sunlight, available water as rainfall, available nutrients in the soil, and temperatures, among other factors, combine to determine growth of a tree, not just temperature alone. It is impossible to distinguish and disentangle the various factors that contribute to tree growth in any given year, much less thousands of years in the past. As a result, one can’t honestly claim that tree growth rings necessarily reflect temperatures alone at a particular time or location, much less that tree rings from one or a few sampled areas show anything about global temperatures or conditions. Making such claims is simply dishonest.

Also, that present temperatures may or may not be warmer than any in the last 2000 years says nothing about whether that is necessarily a bad thing. Historical evidence, in fact, strongly indicates that warmer periods are better for life and human civilization than cooler periods. The authors of this study, assume, without evidence, that just the opposite is the case.

The lead author, Jan Esper, confirms in the interview he gave the BBC that he is, in fact, using this study as a vehicle to elicit policy action:

The authors say the key conclusion from their work is the need for rapid reductions in emissions of planet-warming gases.

“The longer we wait, the more expensive it will be and the more difficult it will be to mitigate or even stop that process and reverse it,” said lead author, Prof Jan Esper from Johannes Gutenberg University, in Germany.

“That is just so obvious,” he said. “We should do as much as possible, as soon as possible.

This admission strongly suggests that the study is more about climate advocacy than science, and the media fell for it. This sort of journalistic malfeasance has become increasingly more common. The study’s authors are acting as advocates not scientists, a path the editors and fact checkers that media outlets employ followed as well in publicizing the report’s unverifiable claims and its authors’ calls for action. If they were actually doing their jobs as journalists to report the truth, the findings of this study never would have been promoted so widely, or if it had been, the writers would have balanced the story with the views of analysts critical of the study, citing scientific evidence.

Tree Rings Reveal Largest Solar Storm EVAH!

Big sun eruption – Elements of this image furnished by NASA

The largest known solar storm struck Earth more than 14,000 years ago, according to a new study of the growth rings in ancient trees. Why it matters: The discovery illustrates the immense power of solar storms — and underscores the danger they pose today.

Tree rings of a buried subfossil tree in the Drouzet River in the Southern French Alps. Photo Credit: Cécile Miramont

From Watts Up With That?

Guest “Well, the largest yet identified,” by David Middleton

NEWS RELEASE 9-OCT-2023

Researchers identify largest ever solar storm in ancient 14,300-year-old tree rings

Peer-Reviewed Publication

UNIVERSITY OF LEEDS

An international team of scientists have discovered a huge spike in radiocarbon levels 14,300 years ago by analysing ancient tree-rings found in the French Alps.   

The radiocarbon spike was caused by a massive solar storm, the biggest ever identified.  

A similar solar storm today would be catastrophic for modern technological society – potentially wiping out telecommunications and satellite systems, causing massive electricity grid blackouts, and costing us billions of pounds.  

The academics are warning of the importance of understanding such storms to protect our global communications and energy infrastructure for the future.          

The collaborative research, which was carried out by an international team of scientists, is published today (Oct 9) in The Royal Society’s Philosophical Transactions A: Mathematical, Physical and Engineering Sciences and reveals new insights into the Sun’s extreme behaviour and the risks it poses to Earth.   

[…]Eureka Alert

The paper (Bard et al., 2023) is worth reading.

Myake Events

Such massive solar storms, are known as Myake Events and were unknown to science before 2012. As many as eight additional such solar storms have been identified over the past 15,000 years. The 14.3 kya event would be the most powerful yet identified. 

The discovery of the 774 CE spike fostered new 14C measurement programmes on tree ring series from the Holocene at annual resolution. This is an enormous task since, before this discovery, tree-ring calibration had mainly been based on 14C ages measured on decadal wood sections. So far, four SEP spikes have been evidenced with multiple cosmogenic isotopes, 774 CE (1176 Cal BP), 993 CE (957 Cal BP), 2610 Cal BP, 9125 Cal BP) and a few others have been proposed based solely on 14C, 1052 CE (898 Cal BP), 1279 CE (672 Cal BP), 7210 Cal BP, 7360 Cal BP [17].Bard et al., 2023

The 1859 Carrington Event

The largest, directly-observed, solar storm occurred in 1859 and is known as the Carrington Event. It caused massive disruption on Earth – destroying telegraph machines and creating a night-time aurora so bright that birds began to sing, believing the Sun had begun to rise. However, the Miyake Events (including the newly discovered 14,300-yr-old storm) would have been a staggering entire order-of-magnitude greater in size.  Eureka Alert

As disruptive as the Carrington Event was, Myake Events are an order of magnitude larger than the 1859 Carrington Event.

Greenhouse Gas Emissions vs Solar Storms

A repeat of the Carrington Event would be truly catastrophic to our modern, technology-dependent, society. A Myake Event might actually be an existential threat to life as we know it…. Yet…

Bard, a climate scientist at Collège de France and CEREGE, said learning about the sun’s past behavior is important for forecasting future solar storms, but also for understanding the sun’s impact on Earth’s climate. The sun’s effect on Earth’s climate is not as large as warming from greenhouse gas emissions, but it is a factor to consider in climate models.The Washington Post

  • Myake Events were only first identified in 2012.
  • As many as nine have been identified over the past decade.
  • The timing appears to be random, with an average interval of ~1,200 years.
  • Scientists have no idea if or how they affected the Late Pleistocene to Holocene climates.
  • The cause is unknown.
  • The frequency is unknown.
  • The Carrington Event, an order of magnitude weaker, would wreak havoc on modern society.

Yet… The “scientists” know that greenhouse gas emissions are more important to Earth’s climate than the Sun. The greenhouse effect depends on the Sun. Greenhouse gasses can’t “trap” heat that never reaches the surface of the Earth.

Myake Events and Neoglaciation?

Five Myake Events occurred during the Mid-Holocene Neoglaciation, with four clustered around the maximum glacial advance.

McKay et al., 2020 CPS with historical climate periods and Neoglaciation (Grosjean et al., 2007), with Myake Events.

Bard did note the 14.3 kya appears to have been followed by a 14 kya grand solar minimum that was coincident with the Older Dryas cooling between the Bølling and Allerød interstadials. Maybe, the Myake Event cluster was related to Neoglaciation?

Green New Deal = Anthropogenic Myake Event?

Let’s assume arguendo that “business as usual” will lead to an additional 1 °C of warming and 11 inches of sea level rise over the next 80 years. Most people won’t notice, because they didn’t notice the previous 1 °C of warming and 11 inches of sea level rise. Time is a serious low-pass filter.

This would leave a mark:

A Carrington class storm (see below) could inflict damage and disruption estimated at between $0.6-$2.6 trillion in the United States alone — 20 times the cost of Hurricane Katrina! Major transformer damage/failure and permanent loss of generator step ups nationwide would take 4-10 years to recover from. The loss of electricity would ripple across the social infrastructure with water distribution affected within several hours, perishable foods and medications lost in 12-24 hours, loss of heating/air conditioning, sewage disposal, phone service, fuel re-supply and so on. At this point, that sounds apocalyptic, but one would be mistaken to assume that this is a rare occurrence.ELFIN UCLA

Costs trillions and destroys our energy infrastructure? Sounds a lot like the Green New Deal. The Green New Deal might even be an anthropogenic version of a Myake Event. The main differences are that a Carrington/Myake Event would happen over a matter of days, and that the Green New Deal can be prevented.

The Flip Side

Hat tip to Yooper for this Daily Caller article:

Stunning New Discovery Is Going To Make Progressives Hate Science, And Should Terrify Conservatives

BLOG

KAY SMYTHE NEWS AND COMMENTARY WRITER October 12, 2023

A study published Monday detailed how a horrifying solar storm bombarded the Earth right around the end of our last major ice age.

[…]

So, why will progressives hate this research? Well, it’s complicated. But the simplest way to explain it is the data contributes to a much larger body of research that is starting to dispel the origin narrative on climate change, and may mean we’ve spent the last thirty years trying to fight the wrong battle. (RELATED: Dear Kay: I Watched ‘Ancient Apocalypse’ And Now I’m Scared We’re Going To Die Before 2025)

Some of you may have been forced to watch former Vice President Al Gore’s documentary “An Inconvenient Truth” back in the early part of this millennium. The premise of the film was this idea that roughly 12,900 to 11,600 years ago, a mini ice age occurred. And it’ll happen again because of man-made climate change.

What Gore failed to explain was the planet was in the thick of an ice age some 2.6 million years prior. For some unknown reason, around 14,000 years ago, ice sheets started to disappear in some parts of the world, as discussed by the Oak Ridge National Laboratory.

Then, around 12,900 to 11,600 years ago, things got really cold again. This time period is called the Younger Dryas. And just as suddenly as it showed up, the Younger Dryas disappeared, likely because of an asteroid impact.

[…]

And conservatives: be scared. These same people have convinced you that climate change is not a threat. But it is. Just not in the way you’ve been told. We are now threatened by our ignorance toward the power of our cosmos, and the only thing that can change that is you.Daily Caller

D’Oh!

“That’s all I have to say about that.”

That unsaid, the “Dear Kay” link was worse, citing Graham Hancock as a scientific source. Although, I do agree with her advice for weathering a Carrington-style event:

Under this type of cataclysm, all of the technology on Earth will fail within about an hour. We won’t be thrown back to the dark ages, but all of our electrical infrastructure might be. We’d be back to subsistence living, dependent on Mother Nature while societal chaos erupts… until it eases. You can easily prepare for such a calamity by working hard, buying land, working that land, storing water, growing essential medicines and foods.

In a recent conversation with researcher Jimmy Corsetti, he and I both agreed that the most important things you can do to survive any type of event like this is to ensure you live amongst a good, supportive community of neighbors, and to own a gun.(RELATED: Dear Kay: I Watched ‘Ancient Apocalypse’ And Now I’m Scared We’re Going To Die Before 2025)

References

Bard Edouard, Miramont Cécile, Capano Manuela, Guibal Frédéric, Marschal Christian, Rostek Frauke, Tuna Thibaut, Fagault Yoann and Heaton Timothy J. 2023. A radiocarbon spike at 14 300 cal yr BP in subfossil trees provides the impulse response function of the global carbon cycle during the Late Glacial. Phil. Trans. R. Soc. A.3812022020620220206. http://doi.org/10.1098/rsta.2022.0206

Grosjean, Martin, Suter, Peter, Trachsel, Mathias & Wanner, Heinz. (2007). “Ice‐borne prehistoric finds in the Swiss Alps reflect Holocene glacier fluctuations”. Journal of Quaternary Science. 22. 203 – 207. 10.1002/jqs.1111.

Kaufman, D., McKay, N., Routson, C. et al. Holocene global mean surface temperature, a multi-method reconstruction approach. Sci Data 7, 201 (2020). https://doi.org/10.1038/s41597-020-0530-7