Author: Futurity (National Geo)

Researchers are using fluorescence lifetime to shed new light on a peptide associated with Alzheimer’s disease.

Through a new approach using time-resolved spectroscopy and computational chemistry, the researchers found experimental evidence of an alternative binding site on amyloid-beta aggregates. The finding opens the door to the development of new therapies for Alzheimer’s and other diseases associated with amyloid deposits.

Amyloid plaque deposits in the brain are a main feature of Alzheimer’s. The Centers for Disease Control and Prevention estimates Alzheimer’s will affect nearly 14 million people in the US by 2060.

“Amyloid-beta is a peptide that aggregates in the brains of people that suffer from Alzheimer’s disease, forming these supramolecular nanoscale fibers, or fibrils” says Angel Martí, a professor of chemistry, bioengineering, and materials science and nanoengineering at Rice University and faculty director of the Rice Emerging Scholars Program. “Once they grow sufficiently, these fibrils precipitate and form what we call amyloid plaques.

“Understanding how molecules in general bind to amyloid-beta is particularly important not only for developing drugs that will bind with better affinity to its aggregates, but also for figuring out who the other players are that contribute to cerebral tissue toxicity,” he adds.

The Martí group had previously identified a first binding site for amyloid-beta deposits by figuring out how metallic dye molecules were able to bind to pockets formed by the fibrils. The molecules’ ability to fluoresce, or emit light when excited under a spectroscope, indicated the presence of the binding site.

Time-resolved spectroscopy, which the lab used in its latest discovery, “is an experimental technique that looks at the time that molecules spend in an excited state,” Martí says. “We excite the molecule with light, the molecule absorbs the energy from the light photons and gets to an excited state, a more energetic state.”

This energized state is responsible for the fluorescent glow. “We can measure the time that molecules spend in the excited state, which is called lifetime, and then we use that information to evaluate the binding equilibrium of small molecules to amyloid-beta,” Martí says.

In addition to the second binding site, the lab and collaborators from the University of Miami uncovered that multiple fluorescent dyes not expected to bind to amyloid deposits in fact did.

“These findings are allowing us to create a map of binding sites in amyloid-beta and a record of the amino acid compositions required for the formation of binding pockets in amyloid-beta fibrils,” Martí says.

The fact that time-resolved spectroscopy is sensitive to the environment around the dye molecule enabled Martí to infer the presence of the second binding site.

“When the molecule is free in solution, its fluorescence has a particular lifetime that is due to this environment. However, when the molecule is bound to the amyloid fibers, the microenvironment is different and as a consequence so is the fluorescence lifetime,” he explains. “For the molecule bound to amyloid fibers, we observed two different fluorescence lifetimes.

“The molecule was not binding to a unique site in the amyloid-beta but to two different sites. And that was extremely interesting because our previous studies only indicated one binding site. That happened because we were not able to see all the components with the technologies we were using previously,” he adds.

The discovery prompted more experimentation. “We decided to look into this further using not only the probe we designed, but also other molecules that have been used for decades in inorganic photochemistry,” he says.

“The idea was to find a negative control, a molecule that would not bind to amyloid-beta. But what we discovered was that these molecules that we were not expecting would bind to amyloid-beta at all actually did bind to it with decent affinity.”

The findings will also affect the study of “many diseases associated with other kinds of amyloids: Parkinson’s, amyotrophic lateral sclerosis (ALS), Type 2 diabetes, systemic amyloidosis,” Marti says.

Understanding the binding mechanisms of amyloid proteins is also useful for studying nonpathogenic amyloids and their potential applications in drug development and materials science.

“There are functional amyloids that our body and other organisms produce for different reasons that are not associated with diseases,” Martí says. “There are organisms that produce amyloids that have antibacterial effects. There are organisms that produce amyloids for structural purposes, to create barriers, and others that use amyloids for chemical storage. The study of nonpathogenic amyloids is an emerging area of science, so this is another path our findings can help develop.”

The research appears in Chemical Science.

The National Science Foundation and the family of the late Professor Donald DuPré, a Houston-born Rice alumnus and former professor of chemistry at the University of Louisville, supported the research.

Source: Rice University

Researchers have solved a puzzle that could help switchgrass realize its full potential as a low-cost, sustainable biofuel crop and curb our dependence on fossil fuels.

Among switchgrass’s attractive features are that it’s perennial, low maintenance, and native to many states in the eastern US. But it also has a peculiar behavior working against it that has stymied researchers—at least until now.

Berkley Walker’s team in the plant biology department at Michigan State University has revealed why switchgrass stops performing photosynthesis in the middle of the summer—its growing season—limiting how much biofuel it yields.

Published in Frontiers in Plant Science, the knowledge is a key piece to overcoming this quirk and getting the most out of switchgrass.

“We want bigger plants, period, so being able to crack this and lift this limitation, that is the goal,” says Mauricio Tejera-Nieves, a postdoctoral researcher and the study’s lead author.

Tejera-Nieves, Walker, and colleagues discovered the explanation for this limitation in switchgrass’s rhizomes. These are little knobby structures that live underground among the plant’s roots.

If you’ve ever sliced or shredded ginger, you’ve held a rhizome. Rhizomes store food in the form of starch to help plants survive winter, and that starch is made from the sugars photosynthesis produces. Once switchgrass rhizomes are full of starch, they signal the plant to stop making sugars and adding biomass through photosynthesis.

Switchgrass ‘banking’

Tejera-Nieves compared the rhizomes to a bank, albeit a slightly unusual one.

“Imagine getting a call from your bank and they tell you, ‘Hey, your account is full. You can take a vacation, go on sabbatical, do whatever you want. Just stop working because we’re not storing any more money,’” Tejera-Nieves says.

“It’s a very conservative strategy, but it’s one that works for switchgrass. The longer it’s doing photosynthesis in nature, the more likely it is that an animal will eat it or something else bad will happen.”

Although this evolutionary strategy has worked to the plant’s advantage in nature, it is a disadvantage for humans who want to ferment switchgrass’s biomass into biofuel. By understanding the root cause of this behavior, though, researchers can start looking for ways around it.

“Now we can start looking for breeding solutions,” says Walker, an assistant professor in the College of Natural Science who also works in the department of energy’s Plant Research Laboratory. “We can start looking for plants that have an insatiable appetite for photosynthesis.”

Why take summers off?

Switchgrass has yet to join plants including corn and sugarcane as a commercialized source of biofuel.

But that makes sense because those established crops have a huge head start, the researchers say.

Farmers have selected and reproduced versions of those crops that have qualities that are attractive to us, such as higher sugar content, for thousands of years.

Humanity’s interest in switchgrass as a biofuel source is much more recent in comparison. So, it’s only natural that switchgrass exhibits some suboptimal behaviors that researchers would like to iron out, like stopping photosynthesis without explanation.

“The plants get to about midseason and say, ‘Okay, we’re done,’” says Walker.

“As a researcher, you’re literally asking, ‘Why are you doing that? It’s warm, the sun is out, and your leaves are green. What is happening?’” says Tejera-Nieves.

Tejera-Nieves joined Walker’s team with a hypothesis to answer that as well as the means to test it with support from the Great Lakes Bioenergy Research Center, or GLBRC. He suspected that a lack of water might be playing a role.

In addition to awarding Tejera-Nieves a fellowship, the GLBRC built what are called rainfall exclusion shelters in the fields at Michigan State’s W.K. Kellogg Biological Station. These do exactly what their name promises: They exclude rain. Plants underneath the shelters stay dry while their neighbors outside can freely soak up sprinkles, showers, and storms.

The shelters presented the perfect place to test Tejera-Nieves’ idea, even if it didn’t go exactly as he initially predicted.

“If water limitation was the reason for the behavior, the plants under the shelters would do poorly,” Tejera-Nieves says. “But they didn’t. After six months of water limitation, the plants under the shelter were just as happy as the plants outside.”

So, he needed to dig a little deeper—literally—to look at what was happening in the rhizomes. He found that the starch levels of all the plants grew over time until they hit a peak level and then would remain flat. Once that happened, photosynthesis in the plants’ leaves switched off.

“Once the rhizomes are full, the plant just stops,” Tejera-Nieves says.

“You can see it so clearly in the data,” Walker says. “The plants do photosynthesis in the summer to save carbon for the winter and, as soon as they’ve got enough, they shut down.”

One of the next steps for the team is developing a better understanding of the molecular machinery that coordinates this photosynthesis shutdown. That knowledge could reveal even more clues about how to override the plant’s behavior and may prove handy for biofuel crops beyond switchgrass.

“You see similar trends with photosynthesis across perennials,” Walker says. “We’d have to look to be sure, but we think it could be the same mechanism.”

The US Department of Energy, Office of Science, Office of Biological and Environmental Research, the Great Lakes Bioenergy Research Center, the National Science Foundation Long-term Ecological Research Program at Kellogg Biological Station, and Michigan State University AgBioResearch funded the work.

Source: Matt Davenport for Michigan State University

The vast majority of parents believe social media is a major distraction for students, according to a new nationwide study.

For the online study, conducted in November and December, researchers surveyed a nationally representative sample of more than 10,000 parents of K-12 students. An overwhelming majority from across racial groups—African American (70%), Asian (72%), white (75%), Hispanic/Latino (70%)—agreed that social media is a distraction.

Parents of children who attend private schools (82%) were more likely to see social media as a distraction than parents of children in public schools (73%) or charter schools (73%) or those being homeschooled (67%). Interestingly, parents with children in high school (74%), middle school (73%), and elementary school (73%) were equally concerned about the issue.

“Suing social media companies or banning cellphones in classrooms may be trendy, but is unlikely to help students.”

School leaders are also worried. In early January, Seattle Public Schools sued the tech giants behind TikTok, Instagram, Facebook, YouTube, and Snapchat, claiming they’ve created a youth mental health crisis. Most schools prohibit cellphone use in the classroom.

“Suing social media companies or banning cellphones in classrooms may be trendy, but is unlikely to help students,” says Vikas Mittal, a professor of marketing at Rice University’s Jones Graduate School of Business, who conducted the 2022 Collaborative for Customer-Based Execution and Strategy (C-CUBES) K12 Parent Voice Study.

Cellphone usage and social media browsing is ingrained among school-age children, he argues. A Pew Research Center study of teens found more than 95% have access to a cellphone, 94% use the internet almost constantly or several times a day, and 54% say it would be hard for them to give up social media.

“Many years ago, schools were in a race to provide every student with internet access,” Mittal says. “It was seen as a panacea for improving academic achievement. That policy seems to have had some unintended consequences.

“The distractive effect of social media is only exacerbated due to widespread internet access, and today’s school leaders must thread a difficult needle,” he continues. “They must continue providing students with high-quality and equitable internet access due to its potential educational benefits.”

“Policies like curtailing cellphone usage in classes to ensure teachers can teach effectively are necessary but quite limiting,” he adds. “School leaders must proactively work with parents to educate children about the potential downside of social media usage and teach them strategies to self-manage potentially addictive behaviors associated with social media.”

Source: Rice University

Medications like dextromethorphan that are used to treat coughs caused by cold and flu could potentially be repurposed to help people quit smoking cigarettes, a new study shows.

The researchers developed a new machine learning method, where computer programs analyze data sets for patterns and trends, to identify the drugs and say that some of them are already being tested in clinical trials.

Cigarette smoking is risk factor for cardiovascular disease, cancer, and respiratory diseases and accounts for nearly half a million deaths in the United States each year.

While smoking behaviors can be learned and unlearned, genetics also plays a role in a person’s risk for engaging in those behaviors. The researchers found in a prior study that people with certain genes are more likely to become addicted to tobacco.

Using genetic data from more than 1.3 million people, Dajiang Liu, professor of public health sciences, and of biochemistry and molecular biology and Bibo Jiang, assistant professor of public health sciences, both at Penn State, co-led a large multi-institution study that used machine learning to study these large data sets—which include specific data about a person’s genetics and their self-reported smoking behaviors.

The researchers identified more than 400 genes related to smoking behaviors. Since a person can have thousands of genes, they had to determine why some of those genes were connected to smoking behaviors.

Genes that carry instructions for the production of nicotine receptors or are involved in signaling for the hormone dopamine, which make people feel relaxed and happy, had easy-to-understand connections. For the remaining genes, the research team had to determine the role each plays in biological pathways and using that information, figured out what medications are already approved for modifying those existing pathways.

Most of the genetic data in the study is from people with European ancestries, so the machine learning model had to be tailored to not only study that data, but also a smaller data set of around 150,000 people with Asian, African, or American ancestries.

Liu, Jiang, and colleagues identified at least eight medications that could potentially be repurposed for smoking cessation, such as dextromethorphan, which is commonly used to treat coughs caused by cold and flu, and galantamine, which is used to treat Alzheimer’s disease. The study is published in Nature Genetics.

“Repurposing drugs using big biomedical data and machine learning methods can save money, time, and resources,” says Liu, a Penn State Cancer Institute and Penn State Huck Institutes of the Life Sciences researcher. “Some of the drugs we identified are already being tested in clinical trials for their ability to help smokers quit, but there are still other possible candidates that could be explored in future research.”

While the machine learning method was able to incorporate a small set of data from diverse ancestries, Jiang says it’s still important for researchers to build out genetic databases from individuals with diverse ancestries.

“This will only improve the accuracy with which machine learning models can identify individuals at risk for drug misuse and determine potential biological pathways that can be targeted for helpful treatments.”

The authors declare no conflicts of interest. A full list of authors on the project can be found in the manuscript.

The National Institutes of Health and Penn State College of Medicine’s Biomedical Informatics and Artificial Intelligence Program in the Strategic Plan supported the work. The views of the authors do not necessarily represent the views of the funders.

Source: Penn State

Coffee with milk may have an anti-inflammatory effect in humans, a new study shows.

Researchers found that a combination of proteins and antioxidants doubles the anti-inflammatory properties in immune cells. They hope to be able to study the health effects on humans.

Whenever bacteria, viruses, and other foreign substances enter the body, our immune systems react by deploying white blood cells and chemical substances to protect us.

This reaction, commonly known as inflammation, also occurs whenever we overload tendons and muscles and is characteristic of diseases like rheumatoid arthritis.

Antioxidants known as polyphenols are found in humans, plants, fruits, and vegetables. This group of antioxidants is also used by the food industry to slow the oxidation and deterioration of food quality and thereby avoid off flavors and rancidity. Polyphenols are also known to be healthy for humans, as they help reduce oxidative stress in the body that gives rise to inflammation.

But much remains unknown about polyphenols. Relatively few studies have investigated what happens when polyphenols react with other molecules, such as proteins mixed into foods that we then consume.

In a new study, researchers investigated how polyphenols behave when combined with amino acids, the building blocks of proteins. The results have been promising.

“In the study, we show that as a polyphenol reacts with an amino acid, its inhibitory effect on inflammation in immune cells is enhanced,” says Marianne Nissen Lund, a professor in the food science department at the University of Copenhagen, who headed the study in the Journal of Agricultural and Food Chemistry.

“As such, it is clearly imaginable that this cocktail could also have a beneficial effect on inflammation in humans. We will now investigate further, initially in animals. After that, we hope to receive research funding which will allow us to study the effect in humans.”

Twice the inflammation-fighting power

To investigate the anti-inflammatory effect of combining polyphenols with proteins, the researchers applied artificial inflammation to immune cells. Some of the cells received various doses of polyphenols that had reacted with an amino acid, while others only received polyphenols in the same doses. A control group received nothing.

The researchers observed that immune cells treated with the combination of polyphenols and amino acids were twice as effective at fighting inflammation as the cells to which only polyphenols were added.

“It is interesting to have now observed the anti-inflammatory effect in cell experiments. And obviously, this has only made us more interested in understanding these health effects in greater detail. So, the next step will be to study the effects in animals,” says senior author Andrew Williams of the veterinary and animal sciences department.

Anti-inflammatory coffee and milk

In previous studies, the researchers demonstrated that polyphenols bind to proteins in meat products, milk, and beer. In another new study, they tested whether the molecules also bind to each other in a coffee drink with milk. Indeed, coffee beans are filled with polyphenols, while milk is rich in proteins.

“Our result demonstrates that the reaction between polyphenols and proteins also happens in some of the coffee drinks with milk that we studied. In fact, the reaction happens so quickly that it has been difficult to avoid in any of the foods that we’ve studied so far,” says Nissen Lund.

Therefore, the researcher does not find it difficult to imagine that the reaction and potentially beneficial anti-inflammatory effect also occur when other foods consisting of proteins and fruits or vegetables are combined.

“I can imagine that something similar happens in, for example, a meat dish with vegetables or a smoothie, if you make sure to add some protein like milk or yogurt,” says Nissen Lund.

Industry and the research community have both taken note of the major advantages of polyphenols. As such, they are working on how to add the right quantities of polyphenols in foods to achieve the best quality. The new research results are promising in this context as well.

“Because humans do not absorb that much polyphenol, many researchers are studying how to encapsulate polyphenols in protein structures which improve their absorption in the body,” says Nissen Lund. “This strategy has the added advantage of enhancing the anti-inflammatory effects of polyphenols.”

Additional coauthors are from the Technical University of Dresden in Germany. Independent Research Fund Denmark funded the work.

Source: University of Copenhagen

A chameleon-like building material changes its infrared color—and how much heat it absorbs or emits—based on the outside temperature.

On hot days, the material can emit up to 92% of the infrared heat it contains, helping cool the inside of a building. On colder days, however, the material emits just 7% of its infrared, helping keep a building warm.

“We’ve essentially figured out a low-energy way to treat a building like a person; you add a layer when you’re cold and take off a layer when you’re hot,” says assistant professor Po-Chun Hsu of the University of Chicago’s Pritzker School of Molecular Engineering (PME).

“This kind of smart material lets us maintain the temperature in a building without huge amounts of energy.”

According to some estimates, buildings account for 30% of global energy consumption and emit 10% of all global greenhouse gas. About half of this energy footprint is attributed to the heating and cooling of interior spaces.

“For a long time, most of us have taken our indoor temperature control for granted, without thinking about how much energy it requires,” says Hsu, who led the research published in Nature Sustainability. “If we want a carbon-negative future, I think we have to consider diverse ways to control building temperature in a more energy-efficient way.”

Researchers have previously developed radiative cooling materials that help keep buildings cool by boosting their ability to emit infrared, the invisible heat that radiates from people and objects. Materials also exist that prevent the emission of infrared in cold climates.

“A simple way to think about it is that if you have a completely black building facing the sun, it’s going to heat up more easily than other buildings,” says graduate student Chenxi Sui, the first author of the paper.

That kind of passive heating might be a good thing in the winter, but not in the summer.

As global warming causes increasingly frequent extreme weather events and variable weather, there is a need for buildings to be able to adapt; few climates require year-round heating or year-round air conditioning.

Hsu and colleagues designed a non-flammable “electrochromic” building material that contains a layer that can take on two conformations: solid copper that retains most infrared heat, or a watery solution that emits infrared. At any chosen trigger temperature, the device can use a tiny amount of electricity to induce the chemical shift between the states by either depositing copper into a thin film, or stripping that copper off.

In the new paper, the researchers detailed how the device can switch rapidly and reversibly between the metal and liquid states. They showed that the ability to switch between the two conformations remained efficient even after 1,800 cycles.

Then, the team created models of how their material could cut energy costs in typical buildings in 15 different US cities. In an average commercial building, they reported, the electricity used to induce electrochromic changes in the material would be less than 0.2% of the total electricity usage of the building, but could save 8.4% of the building’s annual HVAC energy consumption.

“Once you switch between states, you don’t need to apply any more energy to stay in either state,” says Hsu. “So for buildings where you don’t need to switch between these states very frequently, it’s really using a very negligible amount of electricity.”

So far, Hsu’s group has only created pieces of the material that measure about six centimeters across. However, they imagine that many such patches of the material could be assembled like shingles into larger sheets. They say the material could also be tweaked to use different, custom colors—the watery phase is transparent and nearly any color can be put behind it without affecting its ability to absorb infrared.

The researchers are now investigating different ways of fabricating the material. They also plan to probe how intermediate states of the material could be useful.

“We demonstrated that radiative control can play a role in controlling a wide range of building temperatures throughout different seasons,” says Hsu. “We’re continuing to work with engineers and the building sector to look into how this can contribute to a more sustainable future.”

Source: Sarah C.P. Williams for University of Chicago

Perspective-taking—or putting yourself in our partner’s shoes—reduces the temptation to cheat, research finds.

It also inoculates against other partnership-destroying behaviors, according to the study in the Journal of Sex Research on the findings from three double-blind, randomized experiments.

People cheat for a variety of reasons, according to lead author Gurit Birnbaum, a professor of psychology at Reichman University’s Ivcher School of Psychology in Israel. Birnbaum notes that while people may be satisfied with their relationships, they may still betray their partners. For example, so-called “avoidant types” who feel uncomfortable with intimacy may try to maintain distance and control in their relationship by cheating.

Context is key.

“People often cheat not because they planned to do so,” Birnbaum says. “Rather, the opportunity presented itself and they were too depleted—too tired, too drunk, too distracted—to fight the temptation.”

Coauthor Harry Reis, a professor at the University of Rochester, agrees that there are multiple reasons for cheating. One of the more interesting ones, says Reis, author of Relationships, Well-Being and Behaviour (Routledge, 2018), is that men are more likely to cheat because they feel that their sexual needs are not being met. The evidence has shown that women, on the other hand, are more likely to cheat because they feel that their emotional needs aren’t met.

Across three studies, the 408 total participants (213 Israeli women and 195 Israeli men, ranging in age from 20 to 47) were randomly assigned to either adopt the perspective of their partner or not. The participants were uniformly in monogamous, mixed-sex relationships of at least four months. As part of the experiments, the participants evaluated, encountered, or thought about attractive strangers while the psychologists recorded their expressions of interest in these strangers, as well as their commitment to and desire for their current partners.

The researchers found that adopting a partner’s perspective increased commitment and desire for the partner, while simultaneously decreasing sexual and romantic interest in alternative mates. The findings suggest that perspective taking discourages people from engaging in behaviors that may hurt their partners and damage their relationship.

“Both partners may feel more satisfied with their relationship,” says Birnbaum, “and therefore might be less likely to cheat on each other, even if only one of them adopts this strategy.”

“Perspective taking doesn’t prevent you from cheating, but it lessens the desire to do so,” says Reis. Ultimately, he says, cheating means “prioritizing one’s own goals over the good of the partner and the relationship, so seeing things from the other person’s perspective gives one a more balanced view of these situations.”

According to Birnbaum, the findings can help people understand how to resist short-term temptations: “Active consideration of how romantic partners may be affected by these situations serves as a strategy that encourages people to control their responses to attractive alternative partners and derogate their attractiveness.”

The team did not test if the benefits of perspective taking extended to the participants’ romantic partners who were not part of the experiment. But the researchers have a hunch, because perspective taking generally promotes empathy, understanding, closeness, and caring.

“Both partners may feel more satisfied with their relationship,” says Birnbaum, “and therefore might be less likely to cheat on each other, even if only one of them adopts this strategy.”

Besides reducing the likelihood of infidelity, perspective taking motivates people to have compassion for their partners’ emotions and to seek to strengthen the bond with that partner, thereby boosting the existing relationship.

“People invariably feel better understood, and that makes it easier to resolve disagreements, to be appropriately but not intrusively helpful, and to share joys and accomplishments,” Reis says. “It’s one of those skills that can help people see the ‘us’—rather than the ‘me and you’—in a relationship.”

The research had support from the Israel Science Foundation and the Binational Science Foundation.

Source: University of Rochester

Geochemical evidence suggests that carbon dioxide levels may have been much lower millions of years before the emergence of large forests.

Over 400 million years ago, primitive shrub-like plants covered Earth’s continents. It was during the Devonian period, around 385 million years ago, when shrubs evolved into small trees and forests emerged.

From providing wildlife habitat to reducing erosion and absorbing CO₂ from the air, trees play an important role in maintaining a livable environment. So before trees, you might think CO₂ levels were higher, right?

The new findings, published in Nature Communications, run contrary to that assumption and previous estimates.

Christopher Junium, associate professor of earth and environmental sciences at Syracuse University and his collaborators, including the study’s lead author Tais W. Dahl, associate professor from the Globe Institute at the University of Copenhagen, found that the earliest vascular plants substantially reduced CO₂ levels long before the evolution of forests. This early CO₂ decline may have led to significant global cooling and glaciation during this period.

The team analyzed modern descendants of club mosses, plant fossils, and geochemical data and found that 410–380 million years ago, CO₂ levels were only modestly elevated compared to the present day—about 1.5 times greater than current levels, compared to up to 10 times greater, as previously estimated.

Using paleoclimate and earth systems modeling, they found that CO₂ decline and simultaneous oxygen (O₂) increase, even by the earliest land plants, was enough to have led to significant climatic cooling and partial glaciation, consistent with geological evidence.

Junium’s work on the project involved analyzing Early Devonian Period fossil plant materials for their carbon stable isotope composition. By comparing ratios of carbon, researchers can determine how plants incorporated carbon dioxide from the atmosphere into their tissues during photosynthesis.

“The specific values (of carbon isotopes) can help us determine the concentration of carbon dioxide in the atmosphere,” says Junium, who conducted the research in his lab using an isotope-ratio mass spectrometer, which has been custom modified to allow for analysis of extremely precise nanomolar quantities of fossil carbon.

“The 410- to 380-million-year-old plant materials we analyzed were some of the oldest fossil vascular plants that colonized land before the rise of large forests. The analyses revealed that the ancient plant materials had carbon isotope compositions that were surprisingly similar to modern plants and suggested that the concentration of carbon dioxide in the Early Devonian was not as high as we had thought.”

The new analyses served as a starting point for a deep reexamination of the evidence for high carbon dioxide concentrations prior to the expansion of large forests.

“A new method has enabled us to calculate the CO₂ level in the atmosphere in the past based on plant fossils,” writes Dahl. “We initially applied the method to the time before forests emerged—a time which researchers agreed was characterized by high levels of CO₂ in the atmosphere. We used to think that the emergence of forests reduced the amount of atmospheric CO₂ on Earth. But instead of 4,000 parts per million (ppm), which is the amount researchers assumed was found on the planet back then, we have shown that the figure is close to 600 ppm, which is not far from the level we are approaching today.”

The team ultimately found that the emergence of large forests later in the Devonian may not have played as important of a role in decreasing carbon dioxide as previously thought, despite the fact that evidence suggests that the climate cooled considerably from the Early to the Late Devonian.

“The growth of smaller plants like those we analyzed appear to have induced changes in the terrestrial biosphere sufficient to decrease carbon dioxide and increase oxygen through the growth of soils and weathering of nutrient-rich rocks,” says Junium.

In terms of the study’s impact for the future of climate change, it underscores the growing consensus that Earth’s climate is highly sensitive to CO₂ levels and that efforts to limit further CO₂ increase can only improve the future outlook.

“Just because our results suggest that expansion of forests in the Devonian did not cause a dramatic decrease in carbon dioxide does not mean that afforestation—planting new forests on land without trees—is something we should not do,” says Junium. “Rather, climate mitigation practices need to involve decreasing emissions and multiple means for removing CO₂ from the atmosphere. Planting trees and evaluating ways to increase weathering will be important tools for long-term carbon dioxide reduction and stabilization.”

Dahl adds, “To understand how this works on a global scale, and what the consequences are, it is a good idea to look at what happened in the past when the Earth saw major changes and these mechanisms changed. And that is what this study does.”

Source: Syracuse University

The pace and extent of ice destabilization along West Antarctica’s coast varies according to differences in regional climate, according to a new study.

The researchers combined satellite imagery and climate and ocean records to obtain the most detailed understanding yet of how the West Antarctic Ice Sheet—which contains enough ice to raise global sea level by 11 feet, or 3.3 meters—is responding to climate change.

The findings in Nature Communications show that while the West Antarctic Ice Sheet continues to retreat, the pace of retreat slowed in a key region between 2003 and 2015, driven by ocean temperatures, which were in turn caused by variations in offshore winds.

The marine-based West Antarctic Ice Sheet, home to the vast and unstable Pine Island and Thwaites glaciers, sits on an underwater landmass peaking 1.5 miles, or 2.5 kilometers, below the ocean’s surface.

Since the early 1990s, scientists have observed an abrupt acceleration in ice melt, retreat, and speed in this area, which is attributed in part to human-induced climate change over the past century.

Previous studies indicated that the observed changes could be the onset of an irreversible, ice-sheet-wide collapse, which would continue independently of any further climate-driven influence.

“The idea that once a marine-based ice sheet passes a certain tipping point it will cause a runaway response has been widely reported,” says lead author Frazer Christie at Cambridge University. “Despite this, questions remain about the extent to which ongoing changes in climate still regulate ice losses along the entire West Antarctic coastline.”

Using observations collected by an array of satellites, the new study found pronounced regional variations in how the West Antarctic Ice Sheet has changed since 2003 due to climate change, with the pace of retreat in the Amundsen Sea Sector, an area of West Antarctica facing the Pacific Ocean, having slowed significantly. That’s in contrast to the neighboring Bellingshausen Sea Sector, closer to the tip of the Antarctic Peninsula, where glacier retreat accelerated during that time.

By analyzing climate and ocean records, the researchers linked these regional differences to changes in the strength and direction of offshore surface winds. When the prevailing westerly winds are stronger, more of the deeper, warmer ocean water reaches the surface and increases the rate of ice melt.

Researchers found that winds near the Amundsen Sector slackened between 2003 and 2015, because of a deepening of the Amundsen Sea low pressure system. This system is the key atmospheric circulation pattern in the region, and its center—near which changes in offshore wind strength are greatest—typically sits offshore of its namesake coast for most of the year.

The researchers found that the accelerated response of the glaciers flowing from the Bellingshausen Sea Sector can be explained by more constant winds there, causing more persistent ocean-driven melt.

Ultimately, the study illustrates the complexity of the competing ice, ocean, and atmosphere interactions driving shorter-term changes across West Antarctica, and raises important questions about how quickly the icy continent will evolve in a warming world.

“Ocean and atmospheric forcing mechanisms still really, really matter in West Antarctica,” says coauthor Eric Steig, a professor of earth and space sciences at the University of Washington. “That means that ice-sheet collapse is not inevitable. It depends on how climate changes over the next few decades, which we could influence in a positive way by reducing greenhouse gas emissions.”

And while the strength of the low-pressure cell in the Amundsen Sea is not necessarily tied to levels of greenhouse gases—itself an active area of study—the system’s influence shows that even the West Antarctic ice sheet is sensitive to weather and climate shifts.

Results show that changes in ocean, driven by changes in the winds, can slow down and even reverse the loss of ice, Steig says. But he points out that the effect is local and unlikely to last for more than a few decades.

“Only the most aggressive reductions in greenhouse gas emissions can plausibly turn the situation around in the long term,” Steig says.

Additional coauthors are from the University of Edinburgh. Support for the study came from the Carnegie Trust for the Universities of Scotland; the Scottish Alliance for Geoscience, Environment and Society; the Prince Albert II of Monaco Foundation; the UK Natural Environment Research Council; the US National Science Foundation; the joint UK/US International Thwaites Glacier Collaboration project; and the European Space Agency.

Source: University of Washington