Brakenridge

Supernovae may have kicked off abrupt climate shifts in the past, and they could again

Gabe Allen — Tue, 10 Jun 2025 20:15:29 +0000

Supernovae may have kicked off abrupt climate shifts in the past, and they could again Gabe Allen Tue, 06/10/2025 - 14:15

Gabe Allen

Robert Brakenridge

When a star explodes, it sends high-energy particles out in all directions. This burst of energy can travel through space for thousands of light-years, traversing solar systems and even galaxies.

In a recent paper, published in the Monthly Notices of the Royal Astronomical Society, INSTAAR senior research associate Robert Brakenridge argues that supernovae may be the key to understanding a series of abrupt climate shifts in recent geologic history. The analysis models how such radiation could collide with Earth’s atmosphere, changing its composition. Brakenridge also matches a number of known supernovae to climate shifts preserved in geologic records.

“We have abrupt environmental changes in Earth’s history. That’s solid, we see these changes,” Brakenridge said. “So, what caused them?”

Brakenridge says that, if nearby supernovae caused such changes, further research could help scientists predict similar events in the future and prepare accordingly.

“When nearby supernovae occur in the future, the radiation could have a pretty dramatic effect on human society,” he said. “We have to find out if indeed they caused environmental changes in the past.”

Brakenridge’s recent paper is actually one of many he and others have published on the topic since the 1980s. But, in the past, the idea has rested mainly in the realm of theoretical physics. Brakenridge’s new publication is an effort to link the theory to empirical observations, both in space and here on Earth.

Telescopes and tree rings

In recent years, high-powered, orbital telescopes have offered unprecedented information about the contents and character of supernova radiation. Using these observations, Brakenridge created a more precise model of how this radiation might interact with Earth’s atmosphere than previously possible.

According to the model, a sudden influx of high energy photons from a supernova would thin the ozone layer, which shields the Earth from the Sun’s rays. Simultaneously, the radiation would degrade methane in the stratosphere, a major contributor to the greenhouse effect that keeps the Earth warm. Put together, these interactions would dampen greenhouse warming and increase the amount of ultraviolet radiation that reaches Earth from the sun. Brakenridge predicts that knock-on effects could include selective animal extinctions, increased wildfires and global cooling.

Since supernova radiation isn’t arriving on Earth today, the model can’t yet be tested in situ. Instead, Brakenridge looked to records of the past for further evidence. Specifically, he looked at tree rings. Because trees incorporate atmospheric carbon into their trunks as they grow, scientists can look to these records for a glimpse into ancient atmospheric conditions.

In the new paper, Brakenridge parses tree ring records spanning 15,000 years and identifies 11 spikes in radioactive carbon. He argues that these spikes may have been caused by 11 corresponding supernovae.

“The events that we know of, here on earth, are at the right time and the right intensity,” Brakenridge said.

Predicting supernovae

For now, supernovae are just one possible explanation for these phenomena — solar flares are the most prominent alternative. But, Brakenridge says the evidence is mounting behind his argument. He hopes that further efforts can refine models of environmental effects and correlate them with geologic records — from ice cores to marine sediment to tree rings.

A better understanding of supernova radiation could do more than just satiate curiosity, it could help humans prepare for abrupt climate shifts that could arrive any day. For example, astronomers predict that Betelgeuse, a nearby red supergiant star perched on the shoulder of the Orion constellation, will meet its end in a supernova explosion sometime soon — it could be tomorrow, or any time in the next 100,000 years.

“As we learn more about our nearby neighboring stars, the capability for prediction is actually there,” Brakenridge said. “It will take more modeling and observation from astrophysicists to fully understand Earth’s exposure to such events.”

If you have questions about this story, or would like to reach out to INSTAAR for further comment, you can contact Senior Communications Specialist Gabe Allen at gabriel.allen@colorado.edu.

Robert Brakenridge has spent decades trying to understand how distant exploding stars may have affected Earth’s atmosphere in the past. A new analysis indicates the need for continued research in the field.

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The Vela supernova remnant, the remains of a supernova explosion 800 light-years from Earth in the southern constellation Vela, as seen from the Dark Energy Camera on the Víctor M. Blanco Telescope at Cerro Tololo Inter-American Observatory. In his latest paper, Robert Brakenridge identifies a radioactive carbon anomaly in tree ring records that may have been caused by radiation from the vela supernova entering Earth's atmosphere nearly 13,000 years ago.

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The Vela supernova remnant, the remains of a supernova explosion 800 light-years from Earth in the southern constellation Vela, as seen from the Dark Energy Camera on the Víctor M. Blanco Telescope at Cerro Tololo Inter-American Observatory.

Study finds global surge of flood exposure is from population shifts far more than climate change (Sustain What)

Anonymous — Fri, 06 Aug 2021 06:00:00 +0000

Study finds global surge of flood exposure is from population shifts far more than climate change (Sustain What) Anonymous (not verified) Fri, 08/06/2021 - 00:00

Too often, rising climate risk is conflated with rising CO2. That takes the heat off national and local leaders who can cut drivers of risk on the ground now. Andy Revkin collects in-depth perspective from scientists and others on the global risk of flooding, the inequities and policies that are driving up that risk, and what we can do to manage it. Revkin cites work that involved Albert Kettner and Bob Brakenridge of the DFO Flood Observatory.

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New global map shows populations are growing faster in flood-prone areas (MIT Technology Review)

Anonymous — Thu, 05 Aug 2021 06:00:00 +0000

New global map shows populations are growing faster in flood-prone areas (MIT Technology Review) Anonymous (not verified) Thu, 08/05/2021 - 00:00

Satellite imagery reveals how floods are changing and who’s most at risk. A new global floods database involved Bob Brakenridge and Albert Kettner of the DFO Flood Observatory.

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How trees can track history of supernovas (9News)

Anonymous — Tue, 17 Nov 2020 07:00:00 +0000

How trees can track history of supernovas (9News) Anonymous (not verified) Tue, 11/17/2020 - 00:00

A 9News interview with Bob Brakenridge, author of a new paper suggesting that supernovas have impacted Earth's atmosphere and climate, leaving traces that can be seen in tree rings. Watch a 2-minute video.

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Tree rings may hold clues to earthly impacts of distant supernovas (CU 51��ý Today)

Anonymous — Thu, 12 Nov 2020 07:00:00 +0000

Tree rings may hold clues to earthly impacts of distant supernovas (CU 51��ý Today) Anonymous (not verified) Thu, 11/12/2020 - 00:00

Massive explosions of energy happening thousands of light-years from Earth may have left traces in our planet’s biology and geology, according to new research by CU 51��ý geoscientist Robert Brakenridge. The study, published this month in the International Journal of Astrobiology, probes the impacts of supernovas, some of the most violent events in the known universe. To study those possible impacts, Brakenridge searched through the planet’s tree ring records for the fingerprints of these distant, cosmic explosions. While not conclusive, his findings suggest that relatively close supernovas could theoretically have triggered at least four disruptions to Earth’s climate over the last 40,000 years.

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Brakenridge

Supernovae may have kicked off abrupt climate shifts in the past, and they could again

Telescopes and tree rings

Predicting supernovae

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