Killing giant ragweed just got harder for some Wisconsin farmers

University of Illinois College of Agricultural, Consumer and Environmental Sciences

 

image: 

From left: Felipe Faleco, University of Wisconsin-Madison, hands a bag of PPO-resistant giant ragweed seeds to Pat Tranel, University of Illinois Urbana-Champaign. The team identified the first cases of multiple-herbicide-resistant giant ragweed in Wisconsin and the first ever incidence of Group 14-resistance in these weeds.

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Credit: Rodrigo Werle, University of Wisconsin-Madison

URBANA, Ill -- When giant ragweed takes hold in a crop field, the towering weed reduces yield and sends plumes of its famously allergy-inducing pollen into the air. There are few tools available to thwart the menace, especially for farmers growing non-GMO soybeans. Now, some Wisconsin farmers are left with even fewer options. 

New research from the University of Wisconsin-Madison and the University of Illinois Urbana-Champaign shows some giant ragweed populations in Wisconsin have evolved resistance to a crucial class of post-emergence herbicides known as protoporphyrinogen oxidase (PPO) inhibitors (Group 14 herbicides).  

“It’s hard to control giant ragweed with pre-emergence herbicides, in part because it's a larger seed and can emerge from greater depths. So farmers depend on post-emergence products. For folks growing non-GMO soybean, those POST products are ALS and PPO, and we already have fairly widespread ALS resistance in giant ragweed,” said study co-author Pat Tranel, professor in the Department of Crop Sciences in the College of Agricultural, Consumer and Environmental Sciences (ACES) at Illinois. 

“Losing PPOs means you're basically out of chemical options,” he added.

The results won’t surprise some Wisconsin farmers. Study co-author Rodrigo Werle, associate professor and Extension weed scientist at UW-Madison, says farmers started mentioning in 2018 that PPOs weren’t working as well. 

“We thought they had issues with application timing, that they were missing the ideal window for application,” Werle said. “But the growers we were working with are very knowledgeable and did everything by the book. Small plants were regrowing after being sprayed, which can be a sign of resistance.” 

The research team asked farmers to collect and send seeds from plants in affected fields. 

“We evaluated fomesafen (a PPO inhibitor) at 1x and 3x the label rate, and a lot of plants survived. Then we evaluated the dose response for fomesafen and lactofen (another PPO). We determined one population had almost 30-fold resistance to fomesafen and almost four-fold resistance to lactofen,” said lead study author Felipe Faleco, a doctoral student at UW-Madison.  

Faleco let plants that survived the 1x rate of fomesafen grow to maturity, then collected seeds and handed them off to Tranel, who had previously determined the molecular basis of ALS and PPO resistance in common ragweed, a close relative of the giant variety.

“We sequenced the genes for the PPO target enzyme and found the same mutation that we’d seen in common ragweed,” Tranel said. “There were really no other mutations, so that is likely the basis of resistance in giant ragweed, too.”

Tranel’s group went farther, developing a molecular tool diagnostic labs can use to detect PPO resistance, offering farmers quick answers.

The Wisconsin team also tested for resistance to acetolactate synthase (ALS) inhibitors and glyphosate, finding four populations with resistance to ALS and two populations with resistance to glyphosate. These types of resistance had already been documented in giant ragweed, but the team also found one population with resistance to both.

“For us in Wisconsin, this is the first time we’ve documented two types of resistance in a single population in giant ragweed,” Werle said. “It shows that it’s not only waterhemp that is evolving multiple resistance. We also have some other weeds we have to keep an eye on.”

Resistance to glyphosate affects GMO soybean growers, who turn to PPO and ALS herbicides in those cases. Similarly, non-GMO growers who can’t use glyphosate rely on these chemistries.  The authors say with ALS and PPO resistance — essentially, zero chemical options — more non-GMO growers may switch to GMO soybeans.

“Farmers plant non-GMO soybeans for the premiums; there’s a financial reason to go that route even though weed control is more difficult,” Werle said. “But if a farmer knows they're dealing with this type of resistance, that could prevent them from growing a non-GMO crop in a sustainable or a profitable way.”

In addition to the potential impacts on farm management and profits, the findings matter for allergy sufferers. 

“As farmers struggle with control, more ragweeds are going to escape and shed pollen,” Tranel said. “So if you're living in a semi-rural area with corn and soybean fields around, it’s likely there's going to be more pollen in the air.”

The study, “Resistance to protoporphyrinogen oxidase inhibitors in giant ragweed (Ambrosia trifida),” is published in Pest Management Science [DOI: 10.1002/ps.8349]. Authors include Felipe Faleco, Filipi Machado, Lucas Bobadilla, Pat Tranel, David Stoltenberg, and Rodrigo Werle. The Wisconsin Soybean Marketing Board supported Faleco’s graduate studies.

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Journal

Pest Management Science

DOI

10.1002/ps.8349 

 

Legal challenges in human brain organoid research and its applications

Institute for the Advanced Study of Human Biology (ASHBi), Kyoto University

 

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Human brain organoids are three-dimensional neural tissues derived from stem cells that can mimic some aspects of the human brain. Their use holds incredible promise for medical advancements, but this also raises complex ethical and legal questions that need careful consideration.

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Credit: WPI-ASHBi/Kyoto University

A recent study has explored the legal and ethical challenges expected to arise in human brain organoid research.

Human brain organoids are three-dimensional neural tissues derived from stem cells that can mimic some aspects of the human brain. Their use holds incredible promise for medical advancements, but this also raises complex ethical and legal questions that need careful consideration.

Seeking to examine the various legal challenges that might arise in the context of human brain organoid research and its applications, the team of researchers, which included a legal scholar, identified and outlined potential legal issues. Notably, the study has evaluated the urgency of these issues, thereby establishing regulatory priorities for the future. The complexities involved in this area have often been overlooked, making this study a crucial step forward.

Legal challenges were categorized into five key themes: consciousness, legal status, consent, ownership, and transplantation. One of the most debated concerns is whether human brain organoids could become conscious. This raises profound ethical and legal questions, even though the realization of such concerns may be distant. The researchers explored the legal implications of different levels of consciousness—from basic sensory experiences to more advanced cognitive functions—suggesting that future legal protections might be necessary.

Another important consideration is the legal status of human brain organoids, which are currently regarded as property, similar to other human-derived materials. However, as research advances, the potential for brain organoids to be integrated into information processing systems and other applications could challenge this classification, possibly leading to discussions about legal personhood.

Consent and ownership also pose unique and pressing challenges. The researchers emphasized the need for appropriate and specific consent from cell donors, especially given the sensitive nature of the research. Ownership disputes may arise as donors might feel a personal connection to the brain organoids or perceive them as belonging to them, particularly as the monetary value of brain organoids increases.

Finally, transplantation of human brain organoids into animals and potentially humans raises another set of ethical and legal issues. Ensuring the welfare of host animals is an urgent concern requiring stringent regulation. In the distant future, addressing the consciousness and welfare of transplanted brain organoids may also be significant concerns.

“Our main finding is that we have, for the first time, thoroughly categorized the legal challenges associated with human brain organoid research on a global scale,” says Dr. Tsutomu Sawai, one of the researchers. This categorization is a significant step toward developing a comprehensive legal framework to improve the research environment for brain organoids.

Looking to the future, the researchers aim to use their findings to guide regulatory action and policy, ensuring responsible and ethical advancement in the field. They encourage public engagement and discussion, emphasizing that diverse perspectives are essential for navigating the complex ethical dimensions of this research. “The results of this research have the potential to bring various benefits to society. While the issues may be complex, we encourage the public to engage with our work, understand the ethical dimensions, and participate in discussions where appropriate,” Dr. Sawai added. “Contributions from different perspectives are essential for the responsible advancement of science.”

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Journal

Journal of Bioethical Inquiry

DOI

10.1007/s11673-024-10349-9 

Article Title

Human Brain Organoid Research and Applications: Where and How to Meet Legal Challenges?

 

WHITE US Congress members’ wealth statistically linked with ancestors’ slaveholding practices

Study provides new evidence that past slaveholding practices might continue to affect people today

Peer-Reviewed Publication

PLOS

 

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Sehgal and Sehgal examined the net worth of members of the U.S. Congress and its relationship with being a descendant of slave owners. Legislators whose ancestors enslaved 16 or more individuals had $3.93 million higher net worth compared to legislators whose ancestors were not slave owners, a five-fold increase. 

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Credit: Anne-Lise Paris, (www.in-graphidi.com), PLOS, CC-BY 4.0

Per a new study, as of April 2021, US Congress members whose ancestors enslaved 16 or more people had a net worth that was five times higher than that of legislators whose ancestors did not have slaves. Neil Sehgal of the University of Pennsylvania, US, and Ashwini Sehgal of Case Western Reserve University, US present these findings in the open-access journal PLOS ONE on August 21, 2024. 

Prior research has linked slavery’s intergenerational effects to contemporary inequality, poverty, education, voting behavior, and life expectancy in the US However, the extent to which past slavery in the US contributes to today’s social and economic conditions remains unclear. 

In 2023, Reuters released an investigative series that captured information on slaveholder ancestry for all 535 individuals who were US Congress members as of April 15, 2021. To boost understanding of US slavery’s potential contemporary effects, Sehgal and Sehgal cross-referenced information from that report with legislators’ self-disclosed finances. 

Statistical analysis of the data revealed that the net worth of US Congress members whose ancestors had 16 or more slaves was about five times higher than that of legislators whose ancestors did not have slaves—even after accounting for demographic factors that could also be linked to net worth, including age, sex, race, ethnicity, and education. 

The researchers note that legislators are not personally responsible for their ancestors’ actions. Nonetheless, the findings provide new evidence suggesting the possibility that past slaveholding practices in the US may continue to affect people today. 

The authors outline a number of limitations of their study. For instance, the findings do not point to any specific mechanism by which slave ownership by ancestors might affect contemporary legislators’ wealth. In addition, the dataset is small, does not account for ancestors’ history of slavery prior to the founding of the U.S. in 1776, and may lack certain financial assets and information that legislators are not required to disclose. And because US Congress members tend to be wealthier, the findings cannot be extrapolated to other US politicians or the general public. 

Additional research in these areas could help clarify links between slaveholder ancestry and current wealth, which may aid efforts to address contemporary social and economic disparities. 

The authors add: “Members of Congress hold significant power to shape policies and set national agendas. Understanding the wealth disparities within this influential group can drive conversations about economic equity and motivate legislators to support policies addressing historical injustices.” 

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In your coverage please use this URL to provide access to the freely available article in PLOS ONE: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0308351 

Citation: Sehgal NKR, Sehgal AR (2024) Slaveholder ancestry and current net worth of members of the United States Congress. PLoS ONE 19(8): e0308351. https://doi.org/10.1371/journal.pone.0308351  

Author Countries: USA 

Funding: The author(s) received no specific funding for this work. 

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Journal

PLoS ONE

DOI

10.1371/journal.pone.0308351 

Method of Research

Observational study

Subject of Research

People

Article Publication Date

21-Aug-2024

AMERIKA

Homicide rates are a major factor in the gap between Black and White life expectancy

The racial life expectancy gap in 2020 and 2021 was driven by homicide rates even more than by COVID-19 deaths

PLOS

 

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S1 Fig. Differences in homicide death rates between Black and White men, 1990–2021. 

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Credit: Light et al., 2024, PLOS ONE, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

Homicide is a major reason behind lower and more variable reduction in life expectancy for Black rather than White men in recent years, according to a new study published August 21, 2024 in the open-access journal PLOS ONE by Michael Light and Karl Vachuska of the University of Wisconsin-Madison, USA.  

The COVID-19 pandemic precipitated a staggering drop in U.S. life expectancy and substantially widened Black-White disparities in lifespan. It also coincided with the largest one-year increase in the U.S. homicide rate in more than a century, with Black men bearing the brunt of these. Despite these trends, there has been limited research on the contribution of homicide to Black-White disparities in life expectancy during the pandemic.  

In the new study, researchers used mortality data and multiple cause of death data files from the National Vital Statistics System division of the National Center for Health Statistics. The data spanned 2019 to 2021, and causes of death were organized into 20 main groupings.  

Whereas Black men were expected to live on average 71.4 years in 2019, this dropped to 67.7 years in 2020. For White men, the corresponding decline was only from 76.4 years to 74.9 years. As a result, the life expectancy racial gap jumped from 5.0 to 7.2 fewer years  for Black relative to White men. 

The researchers found that in 2020 and 2021, homicide was the leading contributor to inequality both in life expectancy and in lifespan variability between Black and White men. Homicide accounted for far more of the racial gap in longevity and lifespan variability than deaths due to COVID-19. In 2021, for instance, the impact of homicide on the racial gap in lifespan variability was nine times greater than deaths from COVID-19. 

The authors conclude that addressing homicides should be at the forefront of any public health discussion aimed at promoting racial health equity. 

The authors add: “Increased homicide is one of the principal reasons why lifespans have become shorter for Black men than White men in recent years. In 2020 and 2021, homicide was the leading contributor to inequality in both life expectancy and lifespan variability between Black and White men, accounting for far more of the racial gap in longevity and variability than deaths from COVID-19.” 

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In your coverage please use this URL to provide access to the freely available article in PLOS ONE: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0308105  

Citation: Light MT, Vachuska K (2024) Increased homicide played a key role in driving Black-White disparities in life expectancy among men during the COVID-19 pandemic. PLoS ONE 19(8): e0308105. https://doi.org/10.1371/journal.pone.0308105  

Author Countries: United States 

Funding: This research is supported by the Romnes Faculty Fellowship provided by the University of Wisconsin-Madison Office of the Vice Chancellor for Research and Graduate Education with funding from the Wisconsin Alumni Research Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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Journal

PLoS ONE

DOI

10.1371/journal.pone.0308105 

Method of Research

Observational study

Subject of Research

People

Article Publication Date

21-Aug-2024

 

Human-wildlife overlap expected to increase across more than half of land on Earth by 2070

University of Michigan

ANN ARBOR—As the human population grows, more than half of Earth's land will experience an increasing overlap between humans and animals by 2070, according to a University of Michigan study.

Greater human-wildlife overlap could lead to more conflict between people and animals, say the U-M researchers. But understanding where the overlap is likely to occur—and which animals are likely to interact with humans in specific areas—will be crucial information for urban planners, conservationists and countries that have pledged international conservation commitments. Their findings are published in Science Advances.

"We found that the overlap between populations of humans and wildlife will increase across about 57% of the global lands, but it will decrease across only about 12% of the global lands. We also found that agricultural and forest areas will experience substantial increases of overlap in the future," said Deqiang Ma, lead author of the study and a postdoctoral research fellow at the U-M Institute for Global Change Biology in the School for Environment and Sustainability. 

The study showed that the human-wildlife overlap will be driven by human population growth rather than climate change. That is, the increase of people settling in previously undeveloped areas will drive the overlap rather than climate change causing animals to shift where they live.

"In many places around the world, more people will interact with wildlife in the coming decades and often those wildlife communities will comprise different kinds of animals than the ones that live there now," said Neil Carter, principal investigator of the study and associate professor of environment and sustainability. "This means that all sorts of novel interactions, good and bad, between people and wildlife will emerge in the near future."

A human-driven issue

To calculate future human-wildlife overlap, the researchers created an index that combined estimates of where people are likely to populate land as well as the spatial distributions of 22,374 species of terrestrial amphibians, birds, mammals and reptiles. 

They drew information about the spatial distribution of vertebrates from previously published data that forecasts where species will live based on their climatic niches. Their estimates of where people are likely to live were based on projections of economic development, global society and demographics.

"The index we created showed that the majority of global lands will experience increases in human-wildlife overlap, and this increasing overlap is the result of the expansion of human population much more so than changes in species distributions caused by climate change," Ma said.

Specifically, the researchers found that areas that currently have and are projected to have high human-wildlife overlap in 2015 and 2070 are concentrated in regions where human population density is already high, including China and India.

In addition to those places where overlap is already high, "another area of major concern are forests, particularly in forests in Africa and South America where we're seeing a large increase in the overlap in the future," Carter said. "The reason that is concerning is because those areas have very high biodiversity that would experience greater pressure in the future."

The researchers also found that median species richness—the variety of species in a given area—is projected to decrease across most forests in Africa and South America. In South America, mammal richness is projected to decline by 33%, amphibian richness by 45%, reptile richness by 40% and bird richness by 37%. In Africa, mammal richness is projected to decline by 21% and bird richness by 26%.

The need for biodiversity

Preserving biodiversity in these zones of overlap has real benefits, Carter says. 

"There are cases of human-wildlife interactions that are both good and bad, but we anticipate that they're going to become more pronounced. For example, COVID19 was the result of human contact with wild animals, and there is concern that new diseases will emerge from greater encounters between people and certain wildlife species," he said. "But you also have species that provide important benefits to people, like reducing the abundances of pests."

For example, part of Ma's data analysis looked at birds that eat insects in agricultural areas and examined where those birds will go under climate change. He found that more than two-thirds of the croplands that will likely experience an increase of human-wildlife overlap by 2070 will see a decline in bird species that can help reduce crop pests.

"What we're doing is finding those areas and saying, if you have cropland or pastures here, are you going to have species move into those areas or species moving away from those areas," Carter said. "Are those new croplands or pastures going to be an additional threat to the species or could there be ecosystem services harnessed for free?"

Scavengers such as vultures and hyenas also play a critical role by cleaning waste from urban areas and other landscapes, Carter said. By clearing waste, scavengers can reduce the prevalence of some human diseases such as rabies, anthrax and bovine tuberculosis.

"Hyenas and other species that are vilified or persecuted because they are scavengers provide a lot of disease reduction benefits," Carter said. "On one hand, they're viewed as a threat, but on the other hand, they're providing free health benefits.

Equitable conservation

Future conservation strategies will have to evolve, especially in regions that previously haven't seen much human settlement, according to the researchers. In the past, a core conservation strategy was to establish protected areas where human access is restricted. This is becoming harder to implement because there are fewer such places.

"There's also a significant environmental justice argument around the validity of telling communities that may have lived in a certain area for generations that they have to move," Carter said. "Our study suggests that with more areas of the world expected to be shared both by people and wildlife, conservation planning will have to get more creative and inclusive."

Conservationists will need to engage local communities to build interest in helping improve the conservation process. This process may include establishing habitat corridors to connect existing protected areas to potentially new areas or to create temporary protected areas during critical periods for wildlife, like breeding periods, as well as other conservation innovations.

"We care a lot about which areas can support populations of endangered species, like tigers, and how human communities interact with these species," Carter said. "In some places it's going to be really hard to do everything at once: to grow crops and have urban areas and protect these species and their habitats. But if we can start planning now, we have a lot of tools to help us promote sustainable coexistence."

Co-authors of the study include Briana Abrahms of the University of Washington, U-M ecologist Jacob Allgeier, Tim Newbold of the University College London and U-M evolutionary ecologist Brian Weeks.

 

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Journal

Science Advances

DOI

10.1126/sciadv.adp7706 

Method of Research

Data/statistical analysis

Subject of Research

Animals

Article Title

Global Expansion of Human-Wildlife Overlap in the 21st Century

Article Publication Date

21-Aug-2024

 

Study finds highest prediction of sea-level rise unlikely

Researchers question model of rapid polar ice collapse, but say retreat is still dire.

Peer-Reviewed Publication

Dartmouth College

In recent years, the news about Earth's climate—from raging wildfires and stronger hurricanes, to devastating floods and searing heat waves—has provided little good news.

A new Dartmouth-led study, however, reports that one of the very worst projections of how high the world's oceans might rise as the planet's polar ice sheets melt is highly unlikely—though it stresses that the accelerating loss of ice from Greenland and Antarctica is nonetheless dire.

The study challenges a new and alarming prediction in the latest high-profile report from the United Nations' Intergovernmental Panel on Climate Change (IPCC) to evaluate the latest climate research and project the long- and near-term effects of the climate crisis. Released in full last year, the IPCC's sixth assessment report introduced a possible scenario in which the collapse of the southern continent's ice sheets would make Antarctica's contribution to average global sea level twice as high by 2100 than other models project—and three times as high by 2300.

Though the IPCC designated this specific prediction as "low likelihood," the potential of the world's oceans rising by as much as 50 feet as the model projects earned it a spot in the report. At that magnitude, the Florida Peninsula would be submerged, save for a strip of interior high ground spanning from Gainesville to north of Lake Okeechobee, with the state's coastal cities underwater.

But that prediction is based on a new hypothetical mechanism of how ice sheets—the thick, land-based glaciers covering polar regions—retreat and break apart. The mechanism, known as the Marine Ice Cliff Instability (MICI), has not been observed and has so far only been tested with a single low-resolution model, the researchers report in the journal Science Advances.

The researchers instead test MICI with three high-resolution models that more accurately capture the complex dynamics of ice sheets. They simulated the retreat of Antarctica's Thwaites Glacier, the 75-mile-wide ice sheet popularly nicknamed the "Doomsday Glacier" for the accelerating rate at which it is melting and its potential to raise global sea levels by more than two feet. Their models showed that even the imperiled Thwaites is unlikely to rapidly collapse during the 21st century as MICI would predict.

Mathieu Morlighem, a Dartmouth professor of earth sciences and the paper's corresponding author, said that the findings suggest that the physics underlying the extreme projection included in the IPCC report are inaccurate, which can have real-world effects. Policymakers sometimes use these high-estimation models when considering the construction of physical barriers such as sea walls or even relocating people who live in low-lying areas, Morlighem said.

"These projections are actually changing people's lives. Policymakers and planners rely on these models and they're frequently looking at the high-end risk. They don't want to design solutions and then the threat turns out to be even worse than they thought," Morlighem said.

"We're not reporting that the Antarctic is safe and that sea-level rise isn't going to continue—all of our projections show a rapid retreat of the ice sheet," he continues. "But high-end projections are important for coastal planning and we want them to be accurate in terms of physics. In this case, we know this extreme projection is unlikely over the course of the 21st century."

Morlighem worked with Dartmouth's Hélène Seroussi, associate professor in the Thayer School of Engineering, along with researchers from the University of Michigan, the University of Edinburgh and the University of St. Andrews in Scotland, and Northumbria University and the University of Stirling in England.

The idea behind MICI is that if an ice shelf—the floating extension of the land-based ice sheet—collapses rapidly, it would potentially leave the ice cliffs that form the outer edge of the ice sheet exposed and unsupported. If these cliffs are tall enough, they would break under its own weight, exposing an even taller cliff and leading to rapid retreat as the ice sheet collapses inward toward the interior like a row of dominos. The loss of this ice into the ocean where it would melt is what would lead to the projected dramatic sea-level rise.

But the authors of the Science Advances study find that the glacial collapse is not that simple or that fast. "Everyone agrees that cliff failure is real—a cliff will collapse if it's too tall. The question is how fast that will happen," Morlighem said. "But we found that the rate of retreat is nowhere near as high as what was assumed in these initial simulations. When we use a rate that is better constrained by physics, we see that ice cliff instability never kicks in."

The researchers focused on Thwaites Glacier because it has been identified as especially vulnerable to collapse as its supporting ice shelf continues to break down. The researchers simulated Thwaites' retreat for 100 years following a sudden hypothetical collapse of its ice shelf, as well as for 50 years under the rate of retreat actually underway.

In all their simulations, the researchers found that Thwaites' ice cliffs never retreated inland at the speed MICI suggests. Instead, without the ice shelf holding the ice sheet back, the movement of the glacier toward the ocean accelerates rapidly, causing the ice sheet to expand away from the interior. This accelerated movement also thins the ice at the glacier's edge, which reduces the height of the ice cliffs and their susceptibility to collapse.

"We're not calling into question the standard, well-established projections that the IPCC's report is primarily based on," Seroussi said. "We're only calling into question this high-impact, low-likelihood projection that includes this new MICI process that is poorly understood. Other known instabilities in the polar ice sheets are still going to play a role in their loss in the coming decades and centuries."

Polar ice sheets are, for example, vulnerable to the established Marine Ice Sheet Instability (MISI), said study coauthor Dan Goldberg, a glaciologist at Edinburgh who was a visiting professor at Dartmouth when the project began. MISI predicts that, without the protection of ice shelves, a glacier resting on a submerged continent that slopes downward toward the interior of the ice sheet will retreat unstably. This process is expected to accelerate ice loss and contribute increasingly to sea-level rise, Goldberg said.

"While we did not observe MICI in the 21st century, this was in part because of processes that can lead to the MISI," Goldberg said. "In any case, Thwaites is likely to retreat unstably in the coming centuries, which underscores the need to better understand how the glacier will respond to ocean warming and ice-shelf collapse through ongoing modeling and observation."

The paper, "The West Antarctic Ice Sheet may not be vulnerable to Marine Ice Cliff Instability during the 21st Century," was published in Science Advances on Aug. 21, 2024. This work was supported by the National Science Foundation (grant no. 1739031) and Natural Environment Research Council (grant nos. NE/S006745/1 and NE/S006796/1).

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Journal

Science Advances

DO

10.1126/sciadv.ado7794 

Method of Research

Computational simulation/modeling

Subject of Research

Not applicable

Article Title

The West Antarctic Ice Sheet may not be vulnerable to Marine Ice Cliff Instability during the 21st Century

Article Publication Date

21-Aug-2024

 

New study reveals devastating power and colossal extent of a giant underwater avalanche off the Moroccan coast

An international research team has mapped a giant underwater avalanche which took place nearly 60,000 years ago in the Agadir Canyon

Peer-Reviewed Publication

University of Liverpool

 

image: 

Overview map of North West African Margin showing the pathway of the event and its erosional marks on the seafloor 

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Credit: University of Liverpool

New research by the University of Liverpool has revealed how an underwater avalanche grew more than 100 times in size causing a huge trail of destruction as it travelled 2000km across the Atlantic Ocean seafloor off the North West coast of Africa.

In a study publishing in the journal Science Advances (and featured on the front cover), researchers provide an unprecedented insight into the scale, force and impact of one of nature’s mysterious phenomena, underwater avalanches.

Dr Chris Stevenson, a sedimentologist from the University of Liverpool’s School of Environmental Sciences, co-led the team that for the first time has mapped a giant underwater avalanche from head to toe, which took place nearly 60,000 years ago in the Agadir Canyon.

Their analysis reveals the event, which started as a small seafloor landslide about 1.5 km3 in volume, grew over 100 times in size picking up boulders, gravel, sand and mud as it travelled through one of the largest submarine canyons in the world before travelling a further 1600km across the Atlantic Sea floor.

The avalanche was so powerful that it eroded the entire 400 km length of the canyon and several hundred metres up the sides – about 4500 km2 in total - and was so strong it carried cobbles more than 130m up the side of the canyon.

Unlike a landslide or snow avalanche, underwater avalanches are impossible to see and extremely difficult to measure. However, they are the primary mechanism for moving material such as sediments, nutrients and pollutants across the surface of the earth and present a significant geohazard to the seafloor infrastructure such as internet cables.

The research team analysed more than 300 core samples from the area taken during research cruises over the last 40 years. This, alongside seismic and bathymetry data, enabled them to map out the giant avalanche.

Dr Stevenson said: “This is the first time anyone has managed to map out an entire individual underwater avalanche of this size and calculate its growth factor.”

“What is so interesting is how the event grew from a relatively small start into a huge and devastating submarine avalanche reaching heights of 200 meters as it moved at a speed of about 15 m/s ripping out the sea floor and tearing everything out in its way.

“To put it in perspective: that’s an avalanche the size of a skyscraper, moving at more than 40 mph from Liverpool to London, which digs out a trench 30 m deep and 15 km wide destroying everything in its path. Then it spreads across an area larger than the UK burying it under about a metre of sand and mud.”

Dr Christoph Bottner, a Marie-Curie research fellow at Aarhus University in Denmark, who co-led the team, said “We calculate the growth factor to be at least 100, which is much larger compared to snow avalanches or debris flows which only grow by about 4-8 times. We have also seen this extreme growth in smaller submarine avalanches measured elsewhere, so we think this might be a specific behaviour associated with underwater avalanches and is something we plan to investigate further.”

Professor Sebastian Krastel, head of Marine Geophysics at Kiel University and chief scientist aboard the cruises that mapped the canyon, added: “Our new insight fundamentally challenges how we view these events. Before this study, we thought that big avalanches only came from big slope failures. But now, we know that they can start small and grow into extremely powerful and extensive giant events.

"These findings are of enormous importance for how we try and assess their potential geohazard risk to seafloor infrastructure like internet cables that carry almost all global internet traffic, which are critical to all aspects of our modern societies.”

The most recent cruises mapping the Agadir Canyon were led by the Institute of Geosciences, Kiel University, Leibniz Institute for Baltic Sea Research and GEOMAR Helmholtz Centre for Ocean Research, Germany. A suite of archive core data was analysed from the British Ocean Sediment Core Repository at NOCS Southampton, which was collected aboard NERC ships over the past 40 years.

The paper ‘Extreme erosion and bulking in a giant submarine gravity low’ is published in the journal Science Advances (doi: 10.1126/sciadv.adp2584).

 

3D image of giant underwater avalanche which took place nearly 60,000 years ago in the Agadir Canyon

Credit

Dr. Christoph Bottner, Aarhus University

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Journal

Science Advances

DOI

10.1126/sciadv.adp2584 

Article Title

Extreme erosion and bulking in a giant submarine gravity low

Article Publication Date

21-Aug-2024