Study yields new insights into the link between global warming and rising sea levels

Understanding the relationship between the Antarctic Ice Sheet and the earth beneath is key to predicting future climate change impacts, finds McGill-led study

McGill University

 

image: 

The ANET-POLENET team flew to remote field sites on Antarctica's Backer Islands to record bedrock uplift. Ohio State University co-author Terry Wilson is second from the left. (Credit: Nicolas Bayou)

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Credit: Nicolas Bayou

A McGill-led study suggests that Earth's natural forces could substantially reduce Antarctica’s impact on rising sea levels, but only if carbon emissions are swiftly reduced in the coming decades. By the same token, if emissions continue on the current trajectory, Antarctic ice loss could lead to more future sea level rise than previously thought.

The finding is significant because the Antarctic Ice Sheet is the largest ice mass on Earth, and the biggest uncertainty in predicting future sea levels is how this ice will respond to climate change.

“With nearly 700 million people living in coastal areas and the potential cost of sea-level rise reaching trillions of dollars by the end of the century, understanding the domino effect of Antarctic ice melt is crucial,” said lead author Natalya Gomez, an Associate Professor in McGill’s Department of Earth and Planetary Sciences and Canada Research Chair in Ice sheet - Sea level interactions.

The study focuses on how the ice sheet interacts with the earth beneath, and how that dynamic is influenced by carbon-emission levels. This relationship has not been thoroughly explored in previous studies, the researchers said.

“Our findings show that while some sea level rise is inevitable, swift and substantive action to lower emissions could prevent some of the most destructive impacts of climate change, particularly for coastal communities,” Gomez said. 

Rising seas and nature’s double-edged sword

As ice melts, its weight decreases, causing the land beneath it to rise like an expanding sponge. The researchers say this process, called post-glacial uplift, can be a double-edged sword.

If emissions drop quickly, limiting global warming, post-glacial uplift can act as a natural brake on ice-mass loss. It lifts the ice up, slowing the flow of ice from land to ocean. The study found this dynamic can reduce Antarctica’s contribution to sea- level rise by up to 40 per cent.

However, if carbon outputs keep pace and the planet heats up quickly, the rebounding land will not be enough to slow the rapidly melting ice, and instead pushes more ocean water away from Antarctica, accelerating sea-level rise along populated coastlines.

To reach their findings, Gomez and collaborating scholars from Canada and the United States developed a 3-D model of Earth’s interior. Their model used geophysical field measurements from the U.S. ANET-POLENET project, which had pioneered large-scale deployments of sensitive instruments to record the bedrock uplift and seismic signals across large expanses of Antarctica.  These extensive field measurements were essential for characterizing the three-dimensional variations of the Antarctic mantle incorporated in the study.

“Our 3-D model peels back Earth’s layers like an onion, revealing dramatic variations in thickness and consistency of the mantle below. This knowledge helps us better predict how different areas will respond to melting,” said co-author Maryam Yousefi, a geodesist at Natural Resources Canada and previously a Postdoctoral Fellow at McGill and Penn State universities.

It’s the first model to capture the relationship between Antarctica's ice and underlying earth in such detail, she added. 

Notes Rob DeConto, a co-author and glaciologist at the University of Massachusetts, “This study marks a breakthrough in our ability to better predict the impacts of climate change on rising seas and to inform effective environmental policy.”

Global impacts

The findings, published in Science Advances, highlight the inequalities of climate change, the scholars noted. Island nations, which contribute the least to global emissions, are likely to bear the brunt of their consequences, they said.

The study is a collaboration between researchers at McGill, Pennsylvania State, Cambridge, Columbia, Colorado State, Ohio State, the University of Massachusetts Amherst, the University of Washington and the Union of Concerned Scientists. It was funded by the Canadian Natural Sciences and Engineering Research Council, the U.S. National Science Foundation and the Canada Research Chairs program.

About McGill University

Founded in 1821, McGill University is home to exceptional students, faculty, and staff from across Canada and around the world. It is consistently ranked as one of the top universities, both nationally and internationally. It is a world-renowned institution of higher learning with research activities spanning three campuses, 12 faculties, 14 professional schools, 300 programs of study and over 39,000 students, including more than 10,400 graduate students.  

McGill’s commitment to sustainability reaches back several decades and spans scales from local to global. The sustainability declarations that we have signed affirm our role in helping to shape a future where people and the planet can flourish.  

Backer Island GNSS system 

The field team used specialized instruments from the ANET-POLENET project that measure Antarctica’s ground motion. This GNSS [GPS] station is located on an island of the Backer Islands chain in Pine Island Bay where the massive Pine Island Glacier enters the Amundsen Sea. 

Credit

Terry Wilson

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Journal

Science Advances

DOI

10.1126/sciadv.adn1470 

Method of Research

Computational simulation/modeling

Article Title

The influence of realistic 3-D mantle viscosity on Antarctica’s contribution to future 3 global sea levels

Article Publication Date

2-Aug-2024

Study shows link between asymmetric polar ice sheet evolution and global climate

Chinese Academy of Sciences Headquarters

 

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Icebergs collapsing from the Antarctic Ice Sheet

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Credit: Photo by LI Yuansheng

Recent joint research led by Professor AN Zhisheng from the Institute of Earth Environment of the Chinese Academy of Sciences has revealed the pivotal role of the growth of the Antarctic ice sheet and associated Southern Hemisphere sea ice expansion in triggering the mid-Pleistocene climate transition (MPT). It has also shown how asymmetric polar ice sheet evolution affects global climate.

The MPT refers to a shift in Earth’s climate system between about ~1.25–0.7 million years ago, marking a shift to more pronounced and regular glacial-interglacial cycles.

While providing insight into the rapid expansion of the Northern Hemisphere ice sheet since the mid-Pleistocene, this study also challenges numerous hypotheses regarding the origin and mechanisms behind the MPT.

Results of the research were published in the recent issue of Science, entitled “Mid-Pleistocene climate transition triggered by Antarctic ice sheet growth.”

Due to the importance of the MPT for the evolution of Earth’s ice sheet dynamics over the last ~1.25 million years, such hypotheses have been debated and discussed frequently in the journals Nature and Science over the last decades.

“This study contributes to our understanding of the question ‘What causes ice ages?’ —one of the 125 frontier scientific problems raised by Science/AAAS in 2021,” said Professor AN, also a member of Chinese Academy of Sciences (CAS) and Foreign Associate of the National Academy of Sciences, USA.

This work also illustrates how processes in the Earth system define and change characteristics of glacial-interglacial cycles, their dynamics, and their length.

Integrating geological records with numerical climate simulations, this study reveals the history of the asymmetric evolution of ice sheets in both hemispheres and the associated response of the Earth’s climate system.

The findings indicate that 2–1.25 million years ago, the ongoing growth of the Antarctic ice sheet and the associated expansion of sea ice in the Southern Hemisphere triggered a temperature drop and water vapor boost in the Northern Hemisphere through the modified cross-equatorial pressure gradient and meridional overturning circulation.

These changes thus fostered development of the Arctic ice sheet and ultimately caused a shift in Earth’s glacial cycles from ~40,000 years to ~100,000 years.

By examining the changes in ice volume across both hemispheres, this work highlights the profound impact of the asymmetric evolution of polar ice sheets upon global climate, particularly on the climate of the Northern Hemisphere.

“The finding of the study that this asymmetry could trigger powerful positive feedbacks that could induce a massive change to Earth’s climate, a point previously unappreciated until now, has important implications for understanding and projecting Earth’s climate under greenhouse warming,” said Dr. CAI Wenju, Fellow of the Australian Academy of Science, who noted that the study is an example of Chinese scientists taking the lead in solving global questions in frontier science.

Prof. AN indicated it was urgent to quantitatively assess links between asymmetric bi-hemispheric ice sheet melting and global climate change. He suggested doing so could advance our ability “to predict future climate change and response of the Earth System to the changes in polar ice sheets.”

This research was a collaboration with international teams including the CAS Institute of Tibetan Plateau Research, the University of Hong Kong, the British Antarctic Survey, Laoshan Laboratory, the Alfred Wegener Institute, Xi’an Jiaotong University, Nanjing University, Brown University, Beijing Normal University, Ocean University of China, and Australian National University.

Clouds typical of Antarctica, influenced by gravity waves, hover above a massive iceberg that has collapsed from an ice sheet.

Credit

Photo by BAN Chao

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Journal

Science

DOI

10.1126/science.abn4861 

Article Title

Mid-Pleistocene climate transition triggered by Antarctic ice sheet growth

Article Publication Date

1-Aug-2024

How the rising earth in Antarctica will impact future sea level rise

Effects will depend on how much global warming is controlled, study finds

Ohio State University

COLUMBUS, Ohio – The rising earth beneath the Antarctic Ice Sheet will likely become a major factor in future sea level rise, a new study suggests. 

Despite feeling like a stationary mass, most solid ground is undergoing a process of deformation, sinking and rising in response to many environmental factors. In Antarctica, melting glacial ice means less weight on the bedrock below, allowing it to rise. How the rising earth interacts with the overlying ice sheet to affect sea level rise is not well-studied, said Terry Wilson, co-author of the study and a senior research scientist at the Byrd Polar and Climate Research Center at The Ohio State University. 

In the new study, Wilson’s colleagues at McGill University developed a model to predict how these interactions could impact global sea level, finding that if humans can lower greenhouse gas emissions and global warming is slowed, upward shifts in the solid earth could reduce Antarctica’s contribution to sea level rise by about 40%, significantly bolstering the best case scenarios for global sea level rise. In this low-emissions scenario, land uplift slows the flow of ice from land to ocean, allowing for more of the ice sheet to be preserved. 

Conversely, if humans are unable to lower carbon emissions in time, ice retreat will outpace uplift, pushing ocean water away from Antarctica and amplifying sea level rise. These events could significantly worsen the most dire models of projected sea level rise along populated coastlines, said Wilson. 

“Our measurements show that the solid earth that forms the base of the Antarctic ice sheet is changing shape surprisingly quickly,“ said Wilson. “The land uplift from reduced ice on the surface is happening in decades, rather than over thousands of years.” 

The study was published today in Science Advances. 

To arrive at these conclusions, the team developed a 3D model of the Earth’s interior using geophysical field measurements from the Antarctic Network (ANET) of the Polar Earth Observing Network (POLENET) project. The mission is focused on studying the changing polar regions by collecting GPS and seismic data from an array of autonomous systems across Antarctica.

Researchers then performed a number of simulations to capture many possible evolutions of Antarctica’s ice sheet and the extent of global sea level rise Earth may experience until the year 2500, according to those parameters.  

“We can project what difference it actually will make if we all contribute to a low-emission scenario now, versus what’s come to be called ‘business as usual’ emissions,” said Wilson, who is also the lead investigator of the ANET-POLENET project. 

She attributes the model’s unprecedented level of detail to how deftly it incorporates data from Antarctica. GPS stations monitor how the land is moving and seismometers measure how fast seismic waves from earthquakes travel through the earth, yielding important insight into where the land uplift will be fast or slow. 

Surprisingly, according to some of the team’s GPS observations processed by researchers at Ohio State, Wilson said, the Antarctic Ice Sheet is currently experiencing a solid earth uplift of about 5 centimeters per year, about 5 times the rate that North America experiences.  

Another significant aspect of the study is how the changes in Antarctica under different carbon emissions scenarios will impact coastlines around the world. Because sea level change will not be uniform, the study notes that nearly 700 million people around the world living in coastal regions will be most impacted by rising seas due to Antarctic ice loss.

Since some regions, such as small island nations, will be more vulnerable than others, mitigating environmental conditions like atmospheric and ocean warming is a vital issue for society, said Wilson. 

“Many people are now more aware they’re experiencing the effects of climate change,” she said. “This work reinforces that our actions as individuals, nations and globally can make a difference in what kind of Earth our offspring will experience in their lifetimes.”

The study results highlight how complex the relationship between the solid earth and the processes that happen atop it is, as well as the importance of continuing to gather enough data to make prompt and accurate predictions about what the next few centuries of our planet will look like. 

“There’s a lot of uncertainty in every model and every prediction that you make,” said Wilson. “But to document how fast our world is changing, it’s very important to continue advancing our ability to make predictions that are more certain, which is the only path that will allow us to tend to our future in a meaningful way.”

Wilson completed the study with colleagues from McGill University, Pennsylvania State University, the University of Massachusetts Amherst, Columbia University, Washington University, Colorado State University and the Union of Concerned Scientists. This study was supported by the U.S National Science Foundation and the Natural Sciences and Engineering Research Council of Canada. 

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Contact: Terry Wilson, Wilson.43@osu.edu

Written by: Tatyana Woodall, Woodall.52@osu.ed

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Journal

Science Advances

DOI

10.1126/sciadv.adn1470 

Method of Research

Computational simulation/modeling

Subject of Research

Not applicable

Article Title

The influence of realistic 3D mantle viscosity on Antarctica’s contribution to future global sea levels

Article Publication Date

2-Aug-2024

UH OH 

Ancient Antarctic microorganisms are aggressive predators

Antarctic dwelling single-celled microorganisms called archaea can behave like parasites, new research published in Nature Communications shows.

Peer-Reviewed Publication

University of Technology Sydney

 

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Electron microscopy showing the parasitic Ca. Nha. antarcticus attached to its host, Hrr. lacusprofundi. 

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Credit: Joshua N Hamm

In Antarctica is a small lake, called Deep Lake, that is so salty it remains ice-free all year round despite temperatures as low as -20 °C in winter. Archaea, a unique type of single-celled microorganism, thrive in this bitterly cold environment.

University of Technology Sydney (UTS) microbiologists Dr Yan Liao and Associate Professor Iain Duggin, from the Australian Institute of Microbiology and Infection, have been studying how these simple, ancient life forms grow and survive. 

“Archaea is one of three lineages of life, alongside Bacteria and Eukarya (organisms whose cells have a membrane-bound nucleus, including plants and animals). They are widespread and play a crucial role in supporting Earth's ecosystems,” said Dr Liao. 

A new study published in Nature Communications, led by Dr Liao and Dr Joshua Hamm from the Royal Netherlands Institute for Sea Research, shows for the first time some of these archaea behave like parasitic predators that rapidly kill their hosts.

“They are less studied and understood than the other lineages. However, archaea provide clues about the evolution of life on Earth, as well as how life might exist on other planets. Their unique biochemistry also holds promising applications in biotechnology and bioremediation. 

“They have been found thriving in very acidic boiling hot springs, deep-sea hydrothermal vents at temperatures well over 100 degrees Celsius, in hypersaline waters like the Dead Sea, as well as in Antarctica,” Dr Liao said.

The archaea used in the study were collected from the cold and hypersaline Deep Lake in Antarctica by Professor Ricardo Cavicchioli, a senior author from UNSW Sydney, who initially led this project. Dr Liao and Associate Professor Duggin have also travelled to Australian pink salt lakes to collect archaea.

Within the archaea, there is a group called DPANN archaea that are much smaller than other archaea, with very small genomes and limited metabolic capabilities. The study reveals they depend on host microbes, particularly other archaea, to survive.

“This is the first time such aggressive behaviour has been observed in archaea. In many ways, the activity is similar to some viruses. It leads us to re-evaluate their ecological role in the Antarctic environment,” said Dr Hamm.

Very few DPANN archaea have been cultivated in the lab, and Dr Liao and colleagues developed new techniques, including unique sample staining, live fluorescence microscopy, and electron microscopy, to visualise the internal parts of the host cells and track interactions between DPANN archaea and their hosts.

Dr Liao stained the host, an archaeon called Halorubrum lacusprofundi, and the parasitic DPANN archaeon Candidatus Nanohaloarchaeum antarcticus, with non-cytotoxic dyes that glow with different colours when exposed to laser light. 

“This allowed us to observe the organisms together over extended periods and identify the cells by colour. We saw DPANN parasites attach, and then appear to move into the host cell, leading to the host cell’s lysis or bursting open,” she said.

Associate Professor Duggin said predators are important players in ecosystems because when they kill their hosts, they not only feed themselves but also make the remains of the host cells available for other organisms to feed on. 

“This allows other microbes to grow and prevents the host organism from hoarding nutrients. The DPANN archaea we investigated appear to play a much more significant role in ecosystems than realised. A parasitic or infection-like lifestyle of these archaea may be common.”

The research was an international collaborative effort involving UTS, the Royal Netherlands Institute for Sea Research, UNSW Sydney, MRC Laboratory of Molecular Biology in Cambridge, and the University of Oxford.

Dr Liao said her future research aims to explore archaea for biomedical and biotechnological applications. While no archaea have been found to cause disease, they could still impact wellbeing. Archaea are also responsible for livestock methane emissions, so a greater knowledge of archaeal lifestyles could be useful to combat climate change. 

 

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Journal

Nature Communications

DOI

10.1038/s41467-024-49962-y 

Method of Research

Imaging analysis

Subject of Research

Cells

Article Title

The parasitic lifestyle of an archaeal symbiont

 

Andean glaciers have retreated to lowest levels in 11,700 years, news study finds

No longer covered in ice, Andean rocks signal the world’s glaciers are melting far faster than predicted, reports an international team of scientists led by Boston College researchers

Boston College

 

image: 

A researcher collects a sample of bedrock from the Queshque Glacier in the Peruvian Andes Mountains. The samples show tropical glaciers have retreated to their smallest size in more than 11,700 years based on cosmogenic nuclide measurements of recently exposed bedrock, an international team of scientists, led by Boston college researchers, reports in the journal Science.

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Credit: Emilio Mateo, Aspen Global Change Institute

Chestnut Hill, Mass (8/1/2024) – Rocks recently exposed to the sky after being covered with prehistoric ice show that tropical glaciers have shrunk to their smallest size in more than 11,700 years, revealing the tropics have already warmed past limits last seen earlier in the Holocene age, researchers from Boston College report today in the journal Science.

Scientists have predicted glaciers would melt, or retreat, as temperatures warm in the tropics – those regions bordering the Earth’s equator. But the study’s analysis of rock samples adjacent to four glaciers in the Andes Mountains shows that glacial retreat has happened far faster and already passed an alarming cross-epoch benchmark, said Boston College Associate Professor of Earth and Environmental Sciences Jeremy Shakun

“We have pretty strong evidence that these glaciers are smaller now than they have been any time in the past 11,000 years,” said Shakun, a paleoclimatologist and co-author of the report. “Given that modern glacier retreat is mostly due to rising temperatures – as opposed to less snowfall, or changes in cloud cover – our findings suggest the tropics have already warmed outside their Holocene range and into the Anthropocene.” 

In other words, the glaciers may no longer be classified as being of the Holocene interglacial period, a significant epoch that saw the birth of civilization, where the flow of water and sea level dictated where towns and cities formed, and where agricultural and commercial activity emerged. Instead, they may be best classified by an epoch that may be well on its way to spelling their end: the Anthropocene.

The findings signal more of the world’s glaciers are likely retreating far faster than predicted, possibly decades ahead of a grim climatological schedule.

“This is the first large region of the planet where we have strong evidence that glaciers have crossed this important benchmark – it is a ‘canary in the coalmine’ for glaciers everywhere,” said Shakun.

Glaciers have been retreating worldwide over the past century but it has been unclear how the magnitude of this retreat compares to the range of natural fluctuations over the past several millennia, Shakun said. The team set out to determine how small tropical glaciers are today compared to their range over the last 11,000 years.

Researchers who formed the international team of scientists traveled to Colombia, Peru, and Bolivia to measure the chemistry of bedrock only recently uncovered in front of four melting glaciers spanning the tropical Andes. Two rare isotopes – beryllium-10 and carbon-14 – build up in bedrock surfaces when they are exposed to cosmic radiation from outer space, Shakun said.

“By measuring the concentrations of these isotopes in the recently exposed bedrock we can determine how much time in the past the bedrock was exposed, which tells us how often the glaciers were smaller than today – kind of like how a sunburn can tell you how long someone was out in the sun,” Shakun said.

Shakun led the project with former BC graduate student Andrew Gorin, partnering with researchers from the University of Wisconsin and Tulane University on the American Cordillera project, then seeking samples and data from colleagues at Aix-Marseille University, the National University of Ireland, Aspen Global Change Institute, Ohio State University, Union College, University Grenoble Alpes, and Purdue University.

“We found essentially no beryllium-10 or radiocarbon-14 in any of the 18 bedrock samples we measured in front of four tropical glaciers,” said Gorin, now a PhD student at UC-Berkeley. “That tells us there was never any significant prior exposure to cosmic radiation since these glaciers formed during the last ice age.”

Twenty years ago, researchers at the Quelccaya Ice Cap in Peru, the largest tropical ice mass in the world, found rooted plant remains melting out of the ice margin as it retreated. Radiocarbon dating showed that those plants were 5,000 years old, indicating Quelccaya had been larger than its size at the time of that study for that whole interval— otherwise the plants would have decayed away if there was a prior period of exposure, Shakun said.

Those Quelccaya findings suggested that modern ice retreat has been abnormally large, but was not yet progressing to an alarming level compared to ice melt across the entire Holocene, Shakun said. He and his team wanted to study a larger number of glaciers and use a technique that can unambiguously show if a glacier was ever smaller than today.

Shakun and his colleagues have been applying the same technique to glaciers along the entire length of the American Cordillera, from Alaska to Tierra del Fuego. The team previously published the results of its North American sampling last year and aims to publish the results from southern South America soon.

“Once we do that, then these studies can all be put together into a global perspective on the current state of glacier retreat,” said Shakun.

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Journal

Science

DOI

10.1126/science.adg7546 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Recent tropical Andean glacier retreat is unprecedented in the Holocene

Article Publication Date

1-Aug-2024

Retreat of tropical glaciers foreshadows changing climate's effect on the global ice

University of Wisconsin-Madison

MADISON — As they are in many places around the globe, glaciers perched high in the Andes Mountains are shrinking. Now, researchers at the University of Wisconsin–Madison and their collaborators have uncovered evidence that the high-altitude tropical ice fields are likely smaller than they've been at any time since the last ice age ended 11,700 years ago.

That would make the tropical Andes the first region in the world known to pass that threshold as a result of the steadily warming global climate. It also makes them possible harbingers of what's to come for glaciers globally.

"We think these are the canary in the coal mine. The tropics would probably be the first place you'd expect ice to disappear, and that's what we're seeing," says Shaun Marcott, a professor of geoscience at UW–Madison. Marcott guided the research with colleagues at Boston College and Tulane University. Andrew Gorin, a former Boston College graduate student who is now at University of California, Berkeley, led the study, which appears in the Aug. 2, 2024, issue of the journal Science.

Glaciers grow slowly over time in regions where summer weather isn't warm enough to melt all of the previous winter's snowfall. Over time, unmelted snow collects and gets compacted and begins to move under its own weight, resulting in the year-round ice that defines a glacier.

Satellite imagery and on-the-ground observations have provided conclusive evidence for decades that high-altitude glaciers in the Andes are steadily shrinking as warmer temperatures cause them to melt more quickly than falling snow can replenish them.

What has remained unclear, though, is whether the glaciers' dwindling footprints are anomalously small compared to the rest of the period that began at the end of the last ice age, known as the Holocene. Meanwhile, glaciers in other parts of the world were smaller at some points in the early Holocene, when the global climate was warmer and drier than recent millennia.

“We knew that glaciers ebbed and flowed in the past, so we wanted to learn how the behavior of glaciers today — melting due to human-caused climate change — stacks up against their long-term fluctuations,” says Andy Jones, a UW–Madison doctoral student and study co-author.

To answer this question, the team of scientists analyzed the geochemistry of bedrock from areas near the edges of four glaciers in the high tropical Andes, choosing sites that satellite imagery showed were exposed by melting ice in only the last two or three decades.

The team specifically looked for evidence of two unique isotopes — basically chemical flavors — of a pair of elements with the bedrock's quartz crystals: beryllium-10 and carbon-14. These isotopes are only present in rock that has spent time at or near the Earth's surface as they result from interactions between the rock and cosmic rays, which are high-energy particles that constantly rain down on the planet from outer space.

Bedrock accumulates beryllium-10 and carbon-14 once it's exposed to the surface, so measuring the isotopes' concentrations in rock crystals near glaciers can be useful for understanding the previous extent of ice coverage.
            The team found "remarkably low" concentrations of both isotopes in nearly all samples, suggesting that melting ice has exposed bedrock near the glaciers for the first time only recently in most of the sampled locations.

Additional analyses — and the fact that the extremely low concentrations were consistent across sample sites — made the researchers confident that melting ice, rather than erosion, exposed the bedrock.

"It's highly unlikely this is from erosion," says Marcott. "Because the multiple locations we went to all show the same thing."

This consistency points to a single likely conclusion, according to Marcott: The world's tropical glaciers, more than 99% of which are located in the Andes, are the first to shrink beyond what's been seen in the recent geologic past.

"Glaciers are very sensitive to the climate system that they live in," says Marcott. "They really are the place you would look to see some of the first big changes resulting from a warming climate. You can look to these glaciers and imagine what we might be looking at going into the future in other places like the Western United States, which is a no-ice scenario."

This research was supported by the National Science Foundation (EAR-1805620; EAR-1805133; EAR-1805892).

# # #

 

--Will Cushman, wcushman@wisc.edu, 608-263-1986

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Journal

Science

Method of Research

Observational study

Subject of Research

Not applicable

Article Publication Date

1-Aug-2024

Current Andean glacier loss is unprecedented in the Holocene

American Association for the Advancement of Science (AAAS)

Andean tropical glaciers are experiencing unprecedented retreat, according to a new study that reveals their current sizes are the smallest in over 11,700 years. “Our finding … identifies this region as a hot spot in our understanding of the changing state of the cryosphere,” say the authors. Glaciers act as important indicators of climate change, with their global retreat accelerating over recent decades. Examining this retreat in the context of the previous 11,700 years of the Holocene interglacial highlights the impact of modern global warming. Although many glaciers worldwide are smaller today compared to their sizes over the Holocene, it’s recognized that glaciers generally retreated to their smallest extents during the early to mid-Holocene. But today tropical glaciers are experiencing unprecedented retreat, possibly due to factors including increasing temperatures at high altitudes. The Andes – home to over 99% of tropical glaciers – are particularly affected, and may be the first to show significant impacts of human-induced climate change on a regional scale. To determine whether the magnitude of tropical glacier retreat in the Andes today exceeds the bounds of Holocene fluctuations, Andrew Gorin and colleagues analyzed paired cosmogenic carbon-14 (14C) and beryllium-10 (10Be) measurements in 20 bedrock samples collected near the margins of four tropical Andean glaciers. Cosmogenic nucleotide measurements can be used to estimate how long bedrock has been exposed, such as due to loss of overlying ice. Gorin et al. discovered that most bedrock samples had near-zero 14C and 10Be concentrations, suggesting that these locations were covered by ice throughout the Holocene and have only recently been exposed. Thus, the adjacent glaciers are likely smaller now than they have been at any point in the past 11,700 years. “Paired with a similar result in the Arctic, the early emergence of these small, fast-responding glaciers from their Holocene baseline may serve as a ‘canary in the coal mine,’ signaling an approaching contraction of higher-latitude glaciers beyond their interglacial range,” write Gorin and colleagues.

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Journal

Science

DOI

10.1126/science.adg7546 

Article Title

Recent tropical Andean glacier retreat is unprecedented in the Holocene

Article Publication Date

2-Aug-2024

 

New’ herbicides in blackberry production could soon be an option for growers

Long-used herbicides proven safe for weed control in blackberry

University of Arkansas System Division of Agriculture

 

image: 

BLACKBERRY PRODUCTION - Arkansas Agricultural Experiment Station scientist Matt Bertucci discusses his research during a field day. (UA System Division of Agriculture photo by Fred Miller)

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Credit: (UA System Division of Agriculture photo by Fred Miller)

FAYETTEVILLE, Ark. — Two “new” herbicide options could soon be available for blackberry growers during the 2025 growing season.

Recent research by weed scientist Matt Bertucci, assistant professor of horticulture for the Arkansas Agricultural Experiment Station, shows that the herbicides 2,4-D choline and glufosinate are safe and effective in blackberry production. That research is now in the hands of the U.S. Department of Agriculture and the U.S. Environmental Protection Agency awaiting final approval before recommendations can be released to growers.
While these herbicides are not new to agriculture, their use in blackberry cultivation is a novel approach.

“We’re excited about these results because they offer growers new tools for better weed control,” said Bertucci, who discussed this research in an episode of the Food, Farms and Forests podcast. Food, Farms and Forests is produced by the experiment station, the research arm of the University of Arkansas System Division of Agriculture.

Blackberry growers face some challenges in weed control due to the crop's sensitivity to many commonly used herbicides. Additionally, the financial incentives for developing new herbicides specifically for blackberries are low compared to major row crops. This is where the USDA’s IR-4 Project comes into play, supporting the registration of pesticides for specialty crops like blackberries and ensuring that smaller but economically valuable crops receive resources needed for continued research.

“This support is crucial because it helps growers without the chemical companies bearing the full cost and logistical challenges of registration,” Bertucci said.

The research team conducted trials over two years to evaluate the safety and effectiveness of 2,4-D choline and glufosinate on blackberries. These chemicals are commonly used in crops such as rice, corn and soybeans, but this was the first study to test them extensively in blackberry fields.

Bertucci and his team found that established blackberry plants showed minimal, temporary damage symptoms from 2,4-D choline, while glufosinate, when carefully applied, managed to control weeds without harming young blackberry plants.

2,4-D choline, a synthetic herbicide known for its broadleaf weed control, was tested on established blackberry plants. The trials involved applications before the plants broke dormancy, during active growth, and post-harvest. Results showed comparable yields and only minor, short-lived damage to the plants, indicating that 2,4-D choline can be a safe option for established blackberries, Bertucci said.

Glufosinate, a non-selective herbicide, was tested on newly planted blackberry plugs. The researchers used wax cartons to shield the young plants during herbicide application to avoid direct contact, which could harm the plants. While glufosinate did cause some minor leaf burning, it was restricted to the lower parts of the plants and did not affect overall plant health, Bertucci said. It also helped control new blackberry shoots, reducing the need for manual pruning, he added.

“Currently registered products for post-emergence application in blackberries only control grassy weeds,” Bertucci said. “2,4-D choline and glufosinate will give us some broader activity and let us go after a different set of species that really can cause fits for our growers.”

EPA approval pending

EPA approval is required before growers can legally use the herbicides on blackberries, Bertucci said. While the registration process can be lengthy, he remains hopeful that growers will be able to use these herbicides by the 2025 growing season.

“I’m very excited to do this type of work that growers are excited about implementing and using on their farms,” Bertucci said. “It’s very promising because I know that I have good news to deliver. I had a good discovery, and I’m just waiting to tell people, ‘Go forth and spray.’”

This research was supported by the IR-4 Project under the direction of principal biologist and weed scientist Roger Batts. Collaborators included Wayne Mitchem, Southern Region Small Fruit Consortium coordinator at North Carolina State University, and Marcelo Moretti, associate professor at Oregon State University. Moretti investigated the herbicides on raspberries.

To learn more about the Division of Agriculture research, visit the Arkansas Agricultural Experiment Station website. Follow on X at @ArkAgResearch. To learn more about the Division of Agriculture, visit uada.edu. Follow us on X at @AgInArk. To learn about extension programs in Arkansas, contact your local Cooperative Extension Service agent or visit uaex.uada.edu.

About the Division of Agriculture

The University of Arkansas System Division of Agriculture’s mission is to strengthen agriculture, communities, and families by connecting trusted research to the adoption of best practices. Through the Agricultural Experiment Station and the Cooperative Extension Service, the Division of Agriculture conducts research and extension work within the nation’s historic land grant education system.

The Division of Agriculture is one of 20 entities within the University of Arkansas System. It has offices in all 75 counties in Arkansas and faculty on five system campuses.

The University of Arkansas System Division of Agriculture offers all its Extension and Research programs and services without regard to race, color, sex, gender identity, sexual orientation, national origin, religion, age, disability, marital or veteran status, genetic information, or any other legally protected status, and is an Affirmative Action/Equal Opportunity Employer.

RACHEL CARSON WAS RIGHT

Our Synthetic Environment

Libcom.org

https://files.libcom.org › files › Bookchin M. Our ...

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by M Bookchin · Cited by 317 — Illness may occur under "favorable" as well as "unfavorable" environmental conditions. Heart disease, cancer, arthritis, and diabetes-the most important.

101 pages

 

We should think twice before calling 911 for people experiencing a mental health crisis, advocated Harvard-trained psychiatrist Dr. Rupinder Legha

PLOS

We should think twice before calling 911 for people experiencing a mental health crisis, advocated Harvard-trained psychiatrist Dr. Rupinder Legha, who describes the potential risks of relying on emergency services in the US for mental health crisis management.

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Article URL: https://journals.plos.org/mentalhealth/article?id=10.1371/journal.pmen.0000084

Article Title: Reconsidering calling 911: Is it time to set a new standard for mental health crisis response?

Author Countries: United States

Funding: The authors received no specific funding for this work.

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Journal

PLOS Mental Health

DOI

10.1371/journal.pmen.0000084 

COI Statement

Competing Interests: The authors have declared that no competing interest exist.