Saturday, October 26, 2024

Slowing ocean current could ease Arctic warming -- a little

Weaker AMOC could transport less heat to higher latitudes

University of California - Riverside

The Arctic is warming at three to four times the global average. However, new research suggests the slowing of a key ocean current could reduce projected Arctic warming by up to 2 degrees Celsius by the end of the century.

For years, scientists have warned that unchecked Arctic warming could lead to devastating consequences, threatening wildlife and ushering in an era of more frequent and extreme weather events. Amid concerns for these types of outcomes, a study led by UC Riverside offers some limited relief.

The study, published in the Proceedings of the National Academy of Sciences, examined the effects that the slowing of the Atlantic Meridional Overturning Circulation, or AMOC, may have on the climate in the Arctic. The AMOC is the current that transports heat from the tropics to higher latitudes.

Though temperatures in the Arctic are projected to rise by 10 degrees Celsius by the end of the century, the study shows that when the slowing AMOC current is factored in, Arctic temperatures will only rise by 8 degrees Celsius.

“The AMOC is a critical component of our climate system because it moves heat around the globe,” said Yu-Chi Lee, UCR graduate student in Earth and Planetary Sciences and first author of the study. “We found that its weakening reduces the amount of heat reaching the Arctic, which slows down the rate of warming.”

Despite this potential benefit, the study highlights ongoing concerns for Arctic ecosystems. As sea ice melts, polar bears face habitat loss, which could make it more difficult for them to hunt and survive. Moreover, as the ice disappears, darker open water is exposed, which absorbs more sunlight and further accelerates warming through a process called the albedo effect.

While the slowdown may slightly reduce Arctic warming, the researchers caution that it may cause other climate disruptions. One of the most concerning is a potential shift in the Intertropical Convergence Zone, a tropical rain belt. If this rain belt moves southward, regions that depend on its rainfall could experience more frequent droughts, affecting agriculture and water supplies.

There are also misconceptions about the connection between sea ice and rising sea levels. Melting sea ice doesn’t directly cause sea levels to rise because the ice is already in the water, much like how melting ice cubes in a glass won’t cause it to overflow. However, land ice, such as glaciers, and the expansion of water as it heats up, do contribute to rising sea levels. The AMOC slowdown isn't a major factor in sea level rise, but it brings other significant changes to the climate system.

Wei Liu, UC Riverside associate professor of climate change and co-author of the paper, emphasized the complexity of the AMOC’s role in the global climate. “The AMOC slowdown may offer some temporary relief in the Arctic, but this is not a simple good-news story,” Liu said. “The overall impact on ecosystems and weather patterns, both in the Arctic and globally, could still be severe.”

The research team used a coupled climate model, which integrates interactions between the ocean, atmosphere, land, and sea ice. The researchers isolated the effect of the AMOC by running two simulations: one that allowed the AMOC to slow under the influence of rising greenhouse gases, and another that artificially maintained its strength by removing fresh water from the North Atlantic to increase salinity.

“Our simulations allowed us to clearly see how much of the future Arctic warming is tied to the AMOC slowdown,” Lee said. “Even though the slowdown reduces warming by a couple of degrees, the overall effects on Arctic ecosystems and the global climate system remain severe.”

Lee also emphasized that the slowdown began relatively recently, and there’s still debate among scientists about how long it has been happening and whether it will continue.

“Direct, in-situ observations of AMOC strength began around 2004, so it’s a relatively short timeframe from which to draw long-term conclusions,” she said. “But there are studies suggesting it could collapse by the end of this century, which would have huge implications.”

Looking ahead, Lee remains focused on the bigger picture. “While the AMOC slowdown might provide some short-term benefits, its broader impacts show us that even small shifts in ocean circulation can cause ripple effects across the planet. Climate change is far from a one-region issue,” she said. “The future of the Arctic—and the world—depends on how we respond today.”

Polar bear chases prey on melting ice.

Credit

AWeith

Journal

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2402322121

Article Title

Impacts of Atlantic meridional overturning circulation weakening on Arctic amplification

Studying Wikipedia browsing habits to learn how people learn

Researchers analyze information-seeking styles of 482,760 people from 50 countries and find that gender and education inequality track different types of knowledge exploration. Findings suggest potential cultural drivers of curiosity and learning

University of Pennsylvania

At one point or another, you may have gone online looking for a specific bit of information and found yourself “going down the Wiki rabbit hole” as you discover wholly new, ever-more fascinating related topics—some trivial, some relevant—and you may have gone so far down the hole it’s difficult to piece together what brought you there to begin with.

According to the University of Pennsylvania’s Dani Bassett, who recently worked with a collaborative team of researcher to examine the browsing habits of 482,760 Wikipedia readers from 50 different countries, this style of information acquisition is called the “busybody.” This is someone who goes from one idea or piece of information to another, and the two pieces may not relate to each other much.

“The busybody loves any and all kinds of newness, they’re happy to jump from here to there, with seemingly no rhyme or reason, and this is contrasted by the ‘hunter,’ which is a more goal-oriented, focused person who seeks to solve a problem, find a missing factor, or fill out a model of the world,” says Bassett.

In the research, published in the journal Science Advances, Bassett and colleagues discovered stark differences in browsing habits between countries with more education and gender equality versus less equality, raising key questions about the impact of culture on curiosity and learning.

“We observed that countries that had greater inequality, in terms of gender and access to education, had people who were browsing with more intent—seeking closely related information, whereas the people in countries that had more equality were browsing expansively, with more diversity in topics—jumping from topic to topic and collecting loosely connected information,” Bassett says. “While we don’t know exactly why this is, we have our hunches, and we believe these findings will prove useful in helping scientists in our field better understand the nature of curiosity.”

This work builds on a previous study led by assistant professor in the Annenberg School for Communication David Lydon-Staley, who was a postdoctoral researcher in Bassett’s Complex Systems Lab at the time.

In that paper, the team had 149 participants from Philadelphia browse Wikipedia for 15 minutes a day for 21 days. In the course of that study, they identified the two curiosity styles, which were predicted by Perry Zurn, one of the new paper’s coauthors and a professor of philosophy at American University and currently a visiting professor at Cornell University, who studied and analyzed literature from over the last two millennia to home in those these styles of curiosity.

“Beginning this line of work in a small sample allowed us to work out the methods needed to capture the complex information-seeking that accompanies curiosity,” Lydon-Staley says. “Working out those methods then allowed us to scale up and ask whether we could confirm that the styles we observed could be found outside of our sample of Philadelphians.”

Working with Martin Gerlach of the Wikimedia Foundation, who had data of more than two million human browsers, “allowed us to apply our existing methods, and develop new methods, to capture styles of curiosity emerging across 14 different languages of Wikipedia and 50 different countries or territories,” Lydon-Staley says.

The three hunches

The researchers cite three main hypotheses driving the associations between information-seeking approaches and equality.

“One is that it’s possible that countries that have more inequality also have more patriarchal structures of oppression that are constraining the knowledge production approaches to be more Hunter-like,” says Bassett. “Countries that have greater equality, in contrast, are open to a diversity of ideas, and therefore a diversity of ways that we’re engaging in the world. This is more like the busybody—the one that’s moving between ideas in a very open-minded way.”

A second possibility the researchers outline is that browsers go to Wikipedia for different purposes in different countries, citing how someone in a country with higher equality may be going to the site for entertainment or leisure rather than for work.

And the third potential explanation is that people in different countries who come to Wikipedia may have different ages, genders, socioeconomic status, or educational attainment, and that those differences in who’s actually coming to Wikipedia may explain the differences in the browsing patterns.

Making connections

One of the most exciting findings of the study was the confirmation of a third curiosity style—the “dancer,” which had previously only been hypothesized based on Zurn’s research on historical texts.

“The dancer is someone who moves along a track of information but, unlike the busybody, they make leaps between ideas in a creative, choreographed way,” says Zurn. “They don’t jump randomly; they connect different domains to create something new.”

This curiosity style shows a degree of creativity and interdisciplinary thinking, offering a new perspective on how people engage with information. “It’s less about randomness and more about seeing connections where others might not,” Bassett says.

“What this tells us is that people—and likely children—have different curiosity styles, and that might affect how they approach learning,” Bassett says. “A child with a hunter-like curiosity may struggle if assessed using methods that favor the busybody style, or vice versa. Understanding these styles could help us tailor educational experiences to better support individual learning paths.”

Where curiosity may lead next

Looking ahead, the team seeks to explore the factors influencing these curiosity styles.

“One question I’m particularly interested in is whether people browse differently at different times of day—perhaps they’re more hunter-like in the morning and more like busybodies in the evening,” says Bassett.

“This opens up new research avenues, including the role of biological processes in shaping how we seek information,” says Shubhankar Patankar, another author on the paper and a doctoral student in Penn Engineering. He is also keen to understand the implications of the work for AI. “Imparting notions of curiosity to AI systems learning from interactions is an increasingly important area of research,” Patankar says.

The team aims to explore the motivations behind Wikipedia browsing, examining whether users are driven by extrinsic factors, like work, or intrinsic curiosity, like personal interest. Additionally, they are considering expanding their analysis to include other digital platforms where learning and exploration naturally occur.

“Wikipedia is a very special place on the internet,” Lydon-Staley says. “The site features exclusively free content and no commercial advertisements. Much of the rest of the contemporary digital landscape is designed to activate individuals’ buying impulses and customizes our media content. This raises the question of how much we are in charge of where our curiosity takes us in online contexts beyond Wikipedia.”

Dani S. Bassett is the J. Peter Skirkanich Professor at the University of Pennsylvania with a primary appointment in the School of Engineering and Applied Science’s Department of Bioengineering and secondary appointments in the School of Arts & Sciences’ Department of Physics & Astronomy, Penn Engineering’s Department of Electrical and Systems Engineering, and the Perelman School of Medicine’s Departments of Neurology and Psychiatry.

Martin Gerlach is a senior research scientist for the Wikimedia Foundation.

David Lydon-Staley is an assistant professor of communication and principal investigator of the Addiction, Health, & Adolescence Lab in the Annenberg School for Communication at Penn.

Shubhankar Patankar is a Ph.D. student at Penn Engineering.

Dale Zhou was a Ph.D. student in the Perelman School of Medicine who is now a postdoctoral researcher at the University of California at Irvine.

Perry Zurn is an associate professor and director of undergraduate studies in philosophy at American University in the College of Arts and Sciences’ Department of Philosophy and Religion.

This research received support from the George E. Hewitt Foundation for Medical Research, the Center for Curiosity, and the National Institute of Health (Grant K01 DA047417).

Journal

Science Advances

DOI

10.1126/sciadv.adn3268

Method of Research

Observational study

Subject of Research

People

Article Title

Architectural styles of curiosity in global Wikipedia mobile app readership

Article Publication Date

25-Oct-2024

Move along moose, SFU study reveals the ‘most Canadian’ animals

Simon Fraser University

What is the “most Canadian” animal? Spoiler: it’s not the beaver, or the moose.

Published today in the journal The Canadian Field-Naturalist, the study from a team of Simon Fraser University researchers ranks, for the first time ever, species of terrestrial vertebrates in Canada by their level of Canadian evolutionary distinctness: the amount of time animals have evolved independently from other Canadian species.

High ranked species have no close national relatives and can embody up to a hundred million years of evolution shared with none other in the country.

The study found that, overall, amphibians and reptiles are Canada’s most evolutionarily distinct species, with Apalone spinifera – better known as the spiny softshell turtle – being the most evolutionary distinct terrestrial animal in the land.

According to the study, the most nationally evolutionary distinct animals by taxonomic group are:

Spiny Softshell Turtle (turtles)
Mudpuppy (amphibians)
Northern Alligator lizard (reptiles)
Virginia Opossum (mammals)
Belted Kingfisher (birds)
Pond Slider (exotic species)

“We weren't surprised by the Opossum,” says Emma Kominek, a master’s student who collated the lists. “It's Canada's only Marsupial. But the aquatic mudpuppy salamander? That was interesting.”

The authors considered all known Canadian vertebrates (222 mammal, 674 bird, 48 amphibian and 49 reptile living species) and created Top 20 lists for each group based on their national evolutionary distinctiveness (ED) scores.

Researchers measure ED by tracing a species’ entire family tree. The further back in time a species connects to its family tree and the fewer relatives it has overall, the higher its ED score. For these national scores, the researchers considered just the species found in the country.

All the animals in the Top 20 rankings have long evolutionary histories and all have biological features that can’t be found in any other species in Canada. Such species contribute more to the Canadian Tree of Life, an important concept in biology illustrating the history of life on earth.

“Conservation of species at risk is often done at the national level,” says SFU biological sciences professor Arne Mooers, who sits on the Committee on the Status of Endangered Wildlife in Canada, and who led the research. “So, it made sense to consider our national evolutionary heritage in this way.”

In the face of current pressures on biodiversity – such as climate change, habitat loss and limited resources available for conservation – Mooers says the study can serve as a new tool to help national policy-makers prioritize which species to focus conservation efforts on.

Researchers also rated the distinctness of exotic species; animals that are not native to Canada, but that have been introduced as a result of human activity.
Exotic species are not currently considered suitable targets for conservation, but researchers were surprised to find that seven exotic animals cracked the Top 20 National lists.

"Some of these exotic species - like the European Wall Lizard - come from far away, so it makes sense they have no relatives in Canada" said Mooers. "But we were surprised to see the wild horse and feral pig high in the list." In the future, Mooers added, there could be value in considering exotic species as part of Canada's biodiversity.

And what of the mighty beaver’s place as a national icon?

Parks Canada won’t have to pull its likeness from its logos anytime soon.

Two species of beaver still cracked the Top 20 list as Canada’s most distinct mammals: the ironically named American beaver and the mountain beaver at numbers three and six, respectively.

Link: Study and photos

ABOUT SIMON FRASER UNIVERSITY

Who We Are
SFU is a leading research university, advancing an inclusive and sustainable future. Over the past 60 years, SFU has been recognized among the top universities worldwide in providing a world-class education and working with communities and partners to develop and share knowledge for deeper understanding and meaningful impact. Committed to excellence in everything we do, SFU fosters innovation to address global challenges and continues to build a welcoming, inclusive community where everyone feels a sense of belonging. With campuses in British Columbia’s three largest cities—Burnaby, Surrey and Vancouver—SFU has eight faculties that deliver 364 undergraduate degree programs and 149 graduate degree programs for more than 37,000 students each year. The university boasts more than 200,000 alumni residing in 145+ countries.

Journal

The Canadian Field-Naturalist

DOI

10.22621/cfn.v137i4.2673

Article Title

Evolutionary isolation of Canadian terrestrial vertebrate species

Article Publication Date

25-Oct-2024

Can reducing moose numbers help protect Canadian caribou populations from wolf predation?

Wiley

Woodland caribou populations in Canada are declining because of habitat changes that benefit common prey species of wolves (such as moose and deer), leading to increasing numbers of wolves that kill caribou. To protect caribou, wildlife managers have reduced wolf numbers in some caribou ranges, but this may cause moose populations to grow, resulting in a wolf rebound. New research in The Journal of Wildlife Management has found that reducing moose populations to historical levels through hunting could be helpful for caribou conservation.

The analysis included regions in British Columbia and Alberta with high moose populations where lethal wolf removals were annually conducted for caribou recovery. In some places, moose populations were also reduced through hunting. Reducing moose populations led to fewer wolves killed to protect caribou populations; specifically, 3.2 times fewer wolves were removed in areas with reduced moose populations.

“Policies that allow increasing moose abundance in association with wolf removals are anticipated to make ongoing wolf removal objectives increasingly difficult to achieve, thereby challenging caribou conservation,” said corresponding author Michelle L. McLellan, PhD, of the Wildlife Science Centre and the University of British Columbia. “Our findings highlight the importance of considering entire ecosystems when developing policies to protect endangered wildlife.”

URL upon publication: https://onlinelibrary.wiley.com/doi/10.1002/jwmg.22673

Additional Information
NOTE: The information contained in this release is protected by copyright. Please include journal attribution in all coverage. For more information or to obtain a PDF of any study, please contact: Sara Henning-Stout, newsroom@wiley.com.

About the Journal
The Journal of Wildlife Management publishes original research contributing to fundamental wildlife science. Topics encompass biology and ecology of wildlife and their habitats with implications for conservation or management.

About Wiley     
Wiley is one of the world’s largest publishers and a trusted leader in research and learning. Our industry-leading content, services, platforms, and knowledge networks are tailored to meet the evolving needs of our customers and partners, including researchers, students, instructors, professionals, institutions, and corporations. We empower knowledge-seekers to transform today’s biggest obstacles into tomorrow’s brightest opportunities. For more than two centuries, Wiley has been delivering on its timeless mission to unlock human potential. Visit us at Wiley.com. Follow us on Facebook, X, LinkedIn and Instagram.

Journal

The Journal of Wildlife Management

DOI

10.1002/jwmg.22673

Article Title

Restoring historical moose densities results in fewer wolves killed for woodland caribou conservation

Article Publication Date

23-Oct-2024

How mammals got their stride

New study reveals the twists and turns of mammal evolution from a sprawling to upright posture

Harvard University, Department of Organismic and Evolutionary Biology

image:
Land animals exhibit a continuum of limb postures – ranging from ‘sprawled’, with the limbs held out to the side of the body, like lizards, to ‘upright’ or ‘erect’, with the limbs held beneath the body and close to the animal’s midline, like dogs, cats and horses. Upright posture is characteristic of most modern mammals, but when did this key trait evolve?
view more
Credit: Peter Bishop

Mammals, including humans, stand out with their distinctively upright posture, a key trait that fueled their spectacular evolutionary success. Yet, the earliest known ancestors of modern mammals more resembled reptiles, with limbs stuck out to their sides in a sprawled posture.

The shift from a sprawled stance, like that of lizards, to the upright posture of modern mammals, as in humans, dogs, and horses, marked a pivotal moment in evolution. It involved a major reorganization of limb anatomy and function in synapsids—the group that includes both mammals and their non-mammalian ancestors—eventually leading to the therian mammals (marsupials and placentals) we know today. Despite over a century of study, the exact "how," "why," and "when" behind this evolutionary leap has remained elusive.

Now, in a new study published in Science Advances, Harvard researchers provide new insights into this mystery, revealing the shift from a sprawled to upright posture in mammals was anything but straightforward. Using cutting-edge methods that blend fossil data with advanced biomechanical modeling, the researchers found that this transition was surprisingly complex and nonlinear, and occurred much later than previously believed.

Lead author Dr. Peter Bishop, a postdoctoral fellow, and senior author Professor Stephanie Pierce, both in the Department of Organismic and Evolutionary Biology at Harvard, began by examining the biomechanics of five modern species that represent the full spectrum of limb postures, including a tegu lizard (sprawled), an alligator (semi-upright), and a greyhound (upright).

“By first studying these modern species, we greatly improved our understanding of how an animal’s anatomy relates to the way it stands and moves,” said Bishop. “We could then put it into an evolutionary context of how posture and gait actually changed from early synapsids through to modern mammals.”

The researchers extended their analysis to eight exemplar fossil species from four continents spanning 300 million years of evolution. The species ranged from the 35g proto-mammal Megazostrodon to the 88kg Ophiacodon, and included iconic animals like the sail-backed Dimetrodon and the saber-toothed predator Lycaenops. Using principles from physics and engineering, Bishop and Pierce built digital biomechanical models of how the muscles and bones attached to each other. These models allowed them to generate simulations that determined how much force the hindlimbs (back legs) could apply on the ground.

“The amount of force that a limb can apply to the ground is a critical determinant of locomotor performance in animals,” said Bishop. “If you cannot produce sufficient force in a given direction when it’s needed, you won’t be able to run as fast, turn as quickly, or worse still, you could well fall over.”

The computer simulations produced a three-dimensional “feasible force space” that captures a limb’s overall functional performance. “Computing feasible force spaces implicitly accounts for all the interactions that can occur between muscles, joints and bones throughout a limb,” said Pierce. “This gives us a clearer view of the bigger picture, a more holistic view of limb function and locomotion and how it evolved over hundreds of millions of years.”

While the concept of a feasible force space (developed by biomedical engineers) has been around since the 1990s, this study is the first to apply it to the fossil record to understand how extinct animals once moved. The authors packaged the simulations into new “fossil-friendly” computational tools that can aid other paleontologists in exploring their own questions. These tools could also help engineers design better bio-inspired robots that can navigate complex or unstable terrain.

The study revealed several important ‘signals’ of locomotion, including that the overall force-generating ability in the modern species was maximal around the postures that each species used in their daily behavior. Importantly, this meant that Bishop and Pierce could be confident that the results obtained for the extinct species genuinely reflected how they stood and moved when alive.

After analyzing the extinct species, the researchers discovered that locomotor performance peaked and dipped over millions of years, rather than progressing in a simple, linear fashion from sprawling to upright. Some extinct species also appeared to be more flexible—able to shift back and forth between more sprawled or more upright postures, like modern alligators and crocodiles do. While others showed a strong reversal towards more sprawled postures before mammals evolved. Paired with the study’s other results, this indicated that the traits associated with upright posture in today’s mammals evolved much later than previously thought, most likely close to the common ancestor of therians.

These findings also help reconcile several unresolved problems in the fossil record. For example, it explains the persistence of asymmetric hands, feet, and limb joints in many mammal ancestors, traits typically associated with sprawling postures among modern animals. It can also help explain why fossils of early mammal ancestors are frequently found in a squashed, spread-eagle pose – a pose more likely to be achieved with sprawled limbs, while modern placental and marsupial fossils are typically found lying on their sides.

“It is very gratifying as a scientist, when one set of results can help illuminate other observations, moving us closer to a more comprehensive understanding,” Bishop said.

Pierce, whose lab has studied the evolution of the mammalian body plan for nearly a decade, notes that these findings are consistent with patterns seen in other parts of the synapsid body, like the vertebral column. “The picture is emerging that the full complement of quintessentially therian traits was assembled over a complex and prolonged period, with the full suite attained relatively late in synapsid history,” she said.

Beyond mammals, the study suggests that some major evolutionary transitions, like the shift to an upright posture, were often complex and potentially influenced by chance events. For instance, the strong reversal in synapsid posture, back toward more sprawled poses, appears to coincide with the Permian-Triassic mass extinction—when 90% of life was wiped out. This extinction event led to other groups like the dinosaurs becoming the dominant animal groups on land, pushing synapsids back into the shadows. The researchers speculate that due to this “ecological marginalization,” the evolutionary trajectory of synapsids may have changed so much that it altered the way they moved.

Whether this hypothesis turns out to be supported or not, understanding the evolution of mammal posture has long been a complex puzzle. Pierce emphasized how advances in computing power and digital modeling have provided scientists new perspectives to address these ancient mysteries. “Using these new techniques with ancient fossils allows us to have a better perspective of how these animals evolved, and that it wasn't just this simple, linear evolutionary story,” she said. “It was really complicated and these animals were probably living and moving in their environments in ways that we hadn’t appreciated before. There was a lot happening and mammals today are really quite special.”

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Fossil of the early sail-backed synapsid Dimetrodon, from 290 million years ago, one of the species investigated in the study.
Dimetrodon Force Field Simulat [VIDEO] |

The study involved digitizing the fossil skeletons of extinct synapsids, creating digital biomechanical models of the musculoskeletal system of the hindlimb, and using these models to compute the limb’s ability to apply force on the ground in different directions. The result is a three-dimensional ‘feasible force space’, which describes what the limb is capable of achieving during locomotion.

Fossil of the mammal-like cynodont Massetognathus, from 242 million years ago, one of the species investigated in the study