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Friday, January 09, 2026

Clues from the past reveal the West Antarctic Ice Sheet’s vulnerability to warming

Ancient sediment records show the ice sheet retreated at least five times during warmer periods millions of years ago

University of Toyama

Tracking the West Antarctic Ice Sheet during the Pliocene — image:
By studying Pliocene sediments deposited when Earth was warmer than today, the researchers found that the West Antarctic Ice Sheet retreated far inland at least five times. These findings provide critical insight into how the ice sheet may respond to ongoing climate warming and the potential scale of future sea-level rise.
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Credit: Professor Keiji Horikawa from the University of Toyama, Japan

The Thwaites and Pine Island glaciers, located in the Amundsen Sea sector of the West Antarctic Ice Sheet (WAIS), are among the fastest-melting glaciers on Earth. Together, they are losing ice more rapidly than any other part of Antarctica, raising serious concerns about the long-term stability of the ice sheet and its contribution to future sea-level rise.

To better understand the risks that warmer conditions pose to the WAIS, researchers are looking back to the Pliocene Epoch (5.3–2.58 million years ago), when global temperatures were about 3–4 °C higher than today and sea levels stood more than 15 meters higher, with melted ice from Antarctica contributing to much of that rise.

Now, examining a deep-sea sediment from this region, researchers from the IODP Exp379 Scientists, found that the WAIS margin retreated far inland at least five times during the Pliocene period.

The study was led by Professor Keiji Horikawa from the Faculty of Science, University of Toyama, Japan, and included Masao Iwai (Kochi University), Claus-Dieter Hillenbrand (British Antarctic Survey), Christine S. Siddoway (Colorado College), and Anna Ruth Halberstadt (University of Texas at Austin). The findings, made available online on December 22, 2025, and published in Vol. 123 of the journal PNAS on January 6, 2026, highlight the vulnerability of the WAIS to future warming.

“We wanted to investigate whether the WAIS fully disintegrated during the Pliocene, how often such events occurred, and what triggered them,” says Prof. Horikawa.

The team analyzed marine sediments collected during the IODP Expedition 379. The sediments recovered from the Site U1532 on the Amundsen Sea continental rise act as a historical archive, recording changes in ice sheets and ocean conditions over millions of years.

They identified two distinct sediment layers reflecting alternating cold and warm climate phases: thick, gray, and finely laminated clays from cold glacial periods, when ice extended across much of the continental shelf; and thinner, greenish layers formed during warmer interglacial periods. The green color comes from the microscopic algae, indicating open, ice-free ocean waters. Crucially, these warm-period layers also contain iceberg-rafted debris (IRD), small rock fragments carried by icebergs, that broke off from the Antarctic continent. As these icebergs drifted across the Amundsen Sea and melted, they released this debris onto the seafloor.

The team identified 14 prominent IRD-rich intervals between 4.65 and 3.33 million years ago, each interpreted as a major melt event when the WAIS partially retreated.

To determine how far inland the ice had retreated, the researchers analyzed the chemical “fingerprints” of the sediments. They measured isotopes of strontium, neodymium, and lead, which vary depending on the age and type of the source rock. By comparing these signatures with those of modern seafloor sediments and bedrock samples from across West Antarctica, the team traced much of the debris to the continental interior, particularly the Ellsworth-Whitmore Mountains.

The sediment record reveals a consistent four-stage cycle of warming and cooling. During cold glacial periods, the ice sheet was extensive and stable, covering the continent. As the climate warmed, during the early interglacial stage, basal melting began, leading to the inland retreat of the ice sheet. At peak warmth, during the peak interglacial stage, large icebergs calved from the retreating ice margin and transported sediment from the Antarctic interior across the Amundsen Sea. As temperatures cooled again, during the glacial-onset stage, the ice sheet rapidly regrew, pushing previously deposited sediments toward the shelf edge and transporting them further downslope into deeper waters.

“Our data and model results suggest that the Amundsen Sea sector of the WAIS persisted on the shelf throughout the Pliocene, punctuated by episodic but rapid retreat into the Byrd Subglacial Basin or farther inland, rather than undergoing permanent collapse,” says Prof. Horikawa

The findings indicate that the WAIS has undergone retreats far beyond its current extent, underscoring its extreme vulnerability to future warming and its potential to drive substantial sea-level rise.

***

Reference
DOI: 10.1073/pnas.2508341122

About University of Toyama, Japan
University of Toyama is a leading national university located in Toyama Prefecture, Japan, with campuses in Toyama City and Takaoka City. Formed in 2005 through the integration of three former national institutions, the university brings together a broad spectrum of disciplines across its 9 undergraduate schools, 8 graduate schools, and a range of specialized institutes. With more than 9,000 students, including a growing international cohort, the university is dedicated to high-quality education, cutting-edge research, and meaningful social contribution. Guided by the mission to cultivate individuals with creativity, ethical awareness, and a strong sense of purpose, the University of Toyama fosters learning that integrates the humanities, social sciences, natural sciences, and life sciences. The university emphasizes a global standard of education while remaining deeply engaged with the local community.

Website: https://www.u-toyama.ac.jp/en/

About Professor Keiji Horikawa from the University of Toyama, Japan
Keiji Horikawa is a Professor in the Faculty of Science at the University of Toyama, Japan, and a geochemist specializing in paleoceanography and paleoclimate research. His work focuses on reconstructing past climate and ocean conditions through geochemical analyses of marine sediment cores. He participated in the International Ocean Discovery Program Expedition 379 to the Amundsen Sea in 2019 and studies the response of the West Antarctic Ice Sheet to warm Pliocene climates. He heads the Horikawa Lab for Paleoceanography and Geochemistry, which aims to improve understanding of Earth’s climate system.

Funding information
This work was supported by JSPS KAKENHI Grant Numbers JP21H04924 and JP25H01181 and JP21H03590, JP23K21746, and JP25K03252 and was conducted by the support of Joint Research Grant for the Environmental Isotope Study of Research Institute for Humanity and Nature, and partly carried out under the Joint Research Program of the Institute of Low Temperature Science, Hokkaido University (23G056).

C. Siddoway’s contributions were supported by U.S. NSF awards 1917176 and 1939146 was funded through the Natural Environment Research Council (NERC) UK IODP grant NE/T010975/1. E.A. Cowan was supported by a postexpedition award from the U.S. Science Support Program of IODP.

Journal

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2508341122

Method of Research

Observational study

Subject of Research

Not applicable

Article Title

Repeated major inland retreat of Thwaites and Pine Island glaciers (West Antarctica) during the Pliocene

Article Publication Date

6-Jan-2026

Ancient Antarctica reveals a 'one–two punch' behind ice sheet collapse

Binghamton University

When we think of global warming, what first comes to mind is the air: crushing heatwaves that are felt rather than seen, except through the haziness of humid air. But when it comes to melting ice sheets, rising ocean temperatures may play more of a role — with the worst effects experienced on the other side of the globe.

A new paper in Nature Geoscience, “Spatially variable response of Antarctica’s ice sheets to orbital forcing during the Pliocene,” explores the complicated dynamics.

While Binghamton University Associate Professor of Earth Sciences Molly Patterson is the first author, the 43 co-authors include several Binghamton alumni, such as Christiana Rosenberg, MS ’20; Harold Jones ’18; and William Arnuk, PhD ’24. The study’s results directly address one of the main goals of the International Ocean Drilling Program (IODP) Expedition 374: to identify the sensitivity of the Antarctic ice sheet to Earth’s orbital configuration under a variety of climate boundary conditions. Because of this, all shipboard science team members are included as co-authors because of their contributions to the data sets used in the article, Patterson explained.

Their research considers the Antarctic ice sheet during the Late Pliocene period, from 3.3 to 2.6 million years ago. From 3.2 to 2.8 million years ago, the global average temperatures were around 2 to 3° Celsius higher than pre-industrial values, in line with the “middle of the road” scenario for climate change, in which temperatures are expected to rise around 2.7°C by 2100.

“Thus, Pliocene records are considered to be useful analogues for understanding what a future with this level of warming might be like,” Patterson explained.

Climate forcing refers to any external factor that causes a change in Earth’s energy balance —incoming versus outgoing heat — and ultimately leads to warming or cooling in the Earth system.

Non-human factors that can affect this energy balance include tectonic changes, volcanic eruptions and shifts in the sun’s energy output, such as sunspot cycles that happen every 11 years. Another factor is “orbital forcing,” or changes in Earth’s orbit around the sun; this has typically driven glacial and interglacial cycles, which have lasted around 100,000 years — at least for the last 800,000 years or so.

The non-human factors that affect the Earth’s climate occur on different time scales, Patterson said.

“Here we are using geological archives to test how these important components of the climate system respond naturally to warmer climates,” she said.

Antarctica is primarily divided into two sectors: West Antarctica, where the ice sheet sits in the ocean, and East Antarctica, where the ice sheet primarily sits on land. During the warm periods of the Pliocene, large parts of West Antarctica and some low-lying areas of East Antarctica experienced significant ice-melt, contributing to a 3- to 10-foot rise in global sea levels.

One of the study’s main conclusions: Under warming conditions similar to the Pliocene, the part of West Antarctica located adjacent to the Pacific Ocean will see its ice disappear at a faster rate. Over the long term, however, both oceanic and atmospheric warming will contribute to rising global sea levels.

You can think of it as an equation of sorts: A warmer climate leads to less sea ice around Antarctica, which then causes the ocean to heat up. Due to the warmer water, the parts of the ice sheet sitting on the ocean melt first. Over time, as the climate continues to warm, the ice sitting on land will also retreat.

“In other words, it’s a one–two punch on the system with a consequence of raising sea levels globally,” Patterson said.

What you may not realize: Because of gravitational effects similar to ocean tides, the loss of ice in the Southern Hemisphere actually has a greater impact on coastlines in the Northern Hemisphere. Conversely, when ice sheets lose mass in the Northern Hemisphere, Southern Hemisphere coastlines are affected more.

With that in mind, New York would be more affected by a 7-meter rise in sea levels from the loss of Antarctic ice than a similar rise from melting ice sheets in Greenland, Patterson pointed out.

Geological archives and modeling experiments provide the long-term context needed to evaluate current changes and help scientists identify the mechanisms that drive the climate system. Ultimately, this research may help us formulate more accurate predictions about our climate change future.

“Basically, geological archives serve as a vital tool for testing the accuracy of climate models used to project future scenarios,” Patterson said.

About Binghamton University

Binghamton University, State University of New York, is the #1 public university in New York and a top-100 institution nationally. Founded in 1946, Binghamton combines a liberal arts foundation with professional and graduate programs, offering more than 130 academic undergraduate majors, minors, certificates, concentrations, emphases, tracks and specializations, plus more than 90 master's, 40 doctoral and 50 graduate certificate programs. The University is home to nearly 18,000 students and more than 150,000 alumni worldwide. Binghamton's commitment to academic excellence, innovative research, and student success has earned it recognition as a Public Ivy and one of the best values in American higher education.

Friday, December 19, 2025

The Doomsday Glacier Flunks 2025 Checkup

Robert Hunziker

December 19, 2025

Image by Amar Adestiempo.

Thwaites, the most studied glacier in the world, commands attention because it is not only the widest in the world at 80 miles but also the shakiest. And its nickname “The Doomsday Glacier” certainly sets it apart from the 500 other named glaciers in Antarctica. Based upon new research of 2024-25, polar scientists have been speaking out like never before, making public predictions about a rapidly deteriorating situation and insisting upon an end to burning fossil fuels, or else!

The new studies identify new concerns: (1) undersea storms that deteriorate/melt from below (2) hundreds of ice earthquakes, fracturing the glacier (3) Thwaites Eastern Ice Shelf, a major portion of the glacier, seriously losing stability.

And finally, a final goodbye to the iconic International Thwaites Glacier Collaboration (ITGC) as it goes dark by year-end 2026. The Trump administration’s FY2026 budget request includes severe cuts to polar science, aiming to end support for the research icebreaker Nathaniel B. Palmer (NBP).

Going forward, Thwaites cascading ice shelves will be unanticipated by polar researchers, as the Nathaniel B. Palmer icebreaker, a veteran of 30 years, is no longer available. It’s been canceled by budget cuts, and the only way to study sea ice is with a vessel. From this point forward, Thwaites abstruse behavior will come as an unwelcomed surprise to coastal megacities of the world.

Nevertheless, as of today, Thwaites followers can exhale because ITGC concluded that the monster glacier will continue to retreat but will not collapse this century and will only account for several inches of sea level rise by 2100. This conclusion is confusing as several recent studies outside of the purview of ITGC are issuing alarm signals of imminent danger and catastrophic sea level rise for today’s generation, which comes as a real shocker, explained herein. This troubling difference of opinion amongst polar scientists likely points to the difficulties in analyses of an ice continent the size of Antarctica, or the US and Mexico combined; thus, subjective opinions become more prominent and can easily radically disagree. Of special note, the disagreement by scientists over future sea level rise is wide enough to drive a Mack truck through.

Thwaites is so over-the-top controversial that it has its own international study group: International Thwaites Glacier Collaboration involving 100 scientists from world-leading research institutes, but going dark soon. Interestingly, the ITGC web site states: “Thwaites Glacier’s retreat has accelerated considerably…, our findings indicate it is set to retreat further, and faster, through the 21st and 22nd centuries, and general collapse of the West Antarctic Ice Sheet over this timeframe cannot be ruled out.” The date of this general statement on the web site is not provided, but ITGC was established in 2018. Additionally, a solution is offered: “Immediate and sustained climate change mitigation (decarbonization) offers the best hope of delaying this ice loss and avoiding initiation of similar unstable retreat in marine-based sectors of East Antarctica.”

In stark contrast to ITCG’s assessment of sea level rise, other studies reported over the past 24 months by polar scientists, who are not necessarily with the ITCG, are bone rattling, e.g. an August 2024 meeting of the Scientific Committee on Antarctic Research, 1,500 scientists: “Antarctica’s glacial melt is advancing faster than ever before in recorded history.” Gino Casassa, glaciologist and head of the Chilean Antarctic Institute, one of the attendees: “Based upon current trends, sea levels will be up 13’ by 2100,” which begs the question of how high by 2035, one decade from now, and furthermore, this projection by Dr. Casassa is wide of the mark of the ITCG. In fact, this is the first known public statement of such an aggressive prediction. Additionally, in general support of Dr. Casassa’s 13-feet, in November 2024, 450 polar scientists held an emergency summit in Australia, stating: “If we don’t act, and quickly, the melting of Antarctica ice could cause catastrophic sea level rise around the globe within our lifetimes.” It is believed this is the first time such a shocking statement, specifically about Antarctica, has been issued by a major gathering of scientists. “Catastrophic, within our lifetimes” is a real punch to the gut.

Both instances go well beyond expectations by the Intergovernmental Panel on Climate Change (IPCC) and ITCG and published research in general. Both call for immediate halt to greenhouse gases, specifically carbon dioxide CO2 emissions from fossil fuel burning as well as decarbonization. Nevertheless, in the face of scientists’ warnings of deep, deep trouble, the United States is taking a path of climate change ignorance. This puts the world at risks which most of today’s American politicians will not have to face because of indeterminate timing, making it easier to “go for the money” and “screw the environment.” As such, sorrowfully, money becomes the new Golden Calf (Book of Exodus). How’d that biblical story work out?

A chilling new study in Science News, University of Manitoba, with a telling headline: Satellites Spot Rapid ‘Doomsday Glacier’ Collapse, Summary: “Two decades of satellite and GPS data show the Thwaites Eastern Ice Shelf slowly losing its grip on a crucial stabilizing point as fractures multiply and ice speeds up. Scientists warn this pattern could spread to other vulnerable Antarctic shelves… The study notes that the pinning point, once a key factor holding the TEIS in place, has slowly shifted into a feature that now contributes to its instability. This four-stage pattern of structural decline may be a signal for other Antarctic ice shelves that appear to be entering similar phases of weakness.” (Debangshu Banerjee, et al, Evolution of Shear‐Zone Fractures Presages the Disintegration of Thwaites Eastern Ice Shelf. Journal of Geophysical Research: Earth Surface, 2025)

Another new study, as of December 2025, published in Nature Geosciences is the first to systematically analyze how the ocean is melting ice shelves over just hours and days, rather than seasons or years, another real shocker. Swirling underwater storms are the protagonists that aggressively melt from down below. The study is listed in CNN Climate, Underwater ‘Storms’ are Eating Away at the Doomsday Glacier. It Could Have a Big Impact on Sea Level Rise d/d Dec. 10, 2025.

Another new study of Thwaites discusses glacial earthquakes, which weaken the gigantic glacier. About two-thirds of the events detected, 245 out of 362, were located near the marine end of Thwaites. Most of these glacial earthquakes are due to capsizing icebergs. A glacial earthquake is created when tall, thin icebergs fall off a glacier into the ocean. When icebergs capsize, they clash violently with the “mother glacier.” This generates strong mechanical ground vibrations, seismic waves, that propagate thousands of kilometers from origin. (Hundreds of Iceberg Earthquakes Detected at the Crumbling End of Antarctica’s ‘Doomsday Glacier’, Phys.org, December 14, 2025).

Whether the Doomsday Glacier craters with a big splash today, tomorrow, or next century, the fact remains that polar scientists agree it is ultra-high risk surrounded by uncertainty. The dimensions are well known, timing of sea level rise is guesswork. But because it is huge and known to be extremely unstable, someday it’ll disrupt civilization beyond the comprehension of today’s stubborn ill-informed climate deniers. And, assuming the 450 polar scientists are close to correct; they’ll see it during their lifetimes. Then what?

Robert Hunziker lives in Los Angeles and can be reached at rlhunziker@gmail.com.

Wednesday, December 10, 2025

A new study reveals how oxygen first reached Earth’s oceans

Researchers use vanadium isotopes to track the rise of oxygen in ancient seas

Woods Hole Oceanographic Institution

Sample — image:
South Africa’s exceptionally preserved ancient rocks hold key evidence for the rise ofatmospheric oxygen. Within them, researchers see the disappearance of sulfur mass-independent fractionation, evidence for a GOE.
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Credit: Photo by Daniel Hentz, ©Woods Hole Oceanographic Institution

Woods Hole, Mass (December 9, 2025) – For roughly two billion years of Earth’s early history, the atmosphere contained no oxygen, the essential ingredient required for complex life. Oxygen began building up during the period known as the Great Oxidation Event (GOE), but when and how it first entered the oceans has remained uncertain.

A new study published in Nature Communications shows that oxygen was absorbed from the atmosphere into the shallow oceans within just a few million years—a geological blink of an eye. Led by researchers at Woods Hole Oceanographic Institution (WHOI), the work provides new insight into one of the most important environmental shifts in Earth’s history.

“At that point in Earth’s history, nearly all life was in the oceans. For complex life to develop, organisms first had to learn not only to use oxygen, but simply to tolerate it,” said Andy Heard, lead author of the study and assistant scientist at WHOI. “Understanding when oxygen first accumulated in Earth’s atmosphere and oceans is essential to tracing the evolution of life. And because ocean oxygenation appears to have followed atmospheric oxygen surprisingly quickly, it suggests that if we detect oxygen in the atmosphere of a distant exoplanet, there’s a strong chance its oceans also contain oxygen.”

Researchers used new chemical analyses of black shales, organic-rich marine sedimentary rocks from South Africa, that formed in the ocean during the ongoing Great Oxidation Event. They found that the trace metal vanadium saw a shift in the relative abundance of its stable isotopes in shales formed before and after the stratigraphic level marking the occurrence of oxygenation in the atmosphere.

“South Africa is one of the few places on Earth with exceptionally well-preserved rock records from this pivotal time in our planet’s history. These sedimentary rocks play host to some of our strongest indicators for the rise of atmospheric oxygen,” said Chad Ostrander, one of the study’s co-authors and an isotope geochemist at the University of Utah. “These rocks have relatively tight age constraints, and within them we see the disappearance of sulfur mass-independent fractionation—the traditional ‘smoking gun’ evidence for a GOE.”

“Vanadium is especially powerful because it responds to relatively high levels of dissolved oxygen compared to other geochemical proxies used for this period of Earth’s history. That means we can detect when oxygen in the oceans first rose above roughly 10 micromoles per liter—a few percent of modern levels,” said Sune Nielsen, one of the study's co-authors and adjunct scientist at WHOI. Nielsen is also noted as one of the first scientists to use the vanadium isotope redox method to study past ocean oxygen levels. “For context, today’s oceans average about 170 micromoles of dissolved oxygen per liter. It’s not much by modern standards, but in oceans that were previously almost entirely oxygen-free, it represents a major step in Earth’s oxygenation.”

These findings show that Earth’s oceans began accumulating oxygen far earlier, and more rapidly, than previously thought, reshaping our understanding of how the planet became habitable for complex life.

“This study helps clarify one of the biggest turning points in Earth’s history,” Heard continued. “By tracing when oxygen first reached the oceans, we’re getting closer to understanding how the conditions for complex life emerged on our planet—and how they might arise elsewhere.”

This work was funded by NASA Exobiology, the WHOI postdoctoral scholar program, the Agouron Institute Fellowship in Geobiology, Discovery and Accelerator Grants from the Natural Sciences and Engineering Research Council of Canada, ACS Petroleum Fund, and the Natural Environmental Research Council.

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About Woods Hole Oceanographic Institution

Woods Hole Oceanographic Institution (WHOI) is a private, non-profit organization on Cape Cod, Massachusetts, dedicated to marine research, engineering, and higher education. Founded in 1930, its mission is to understand the ocean, its interactions with the Earth, and its role in a changing global environment. WHOI’s pioneering discoveries arise from a unique blend of science and engineering that has made it one of the world’s most trusted leaders in ocean research and exploration. Known for its multidisciplinary approach, advanced ship operations, and unmatched deep-sea robotics, WHOI also operates the most extensive suite of ocean data-gathering platforms worldwide. More than 800 concurrent projects—driven by top scientists, engineers, and students—push the boundaries of knowledge to inform people and policy for a healthier planet. Behind the scenes, ship captains, mates, craftsmen, marine operations, and other skilled professionals provide essential support that makes this work possible. Learn more at whoi.edu.

Caption
Researchers analyzed South African black shales and found a shift in vanadiumisotopes across the GOE interval, providing evidence for when Earth’s oceans first becameoxygen-rich.
Credit
(Photo by Daniel Hentz, ©Woods Hole Oceanographic Institution)