Friday, June 13, 2025

 

Cardiovascular disease and diabetes are driving the increase in U.S. excess mortality—and adults without college degrees are bearing most of the burden



About 525,000 more deaths occurred among US adults in 2023 than would be expected had pre-2010 mortality trends continued. More than 90 percent occurred among people without a Bachelor's degree and were largely caused by cardiovascular disease.





Boston University School of Public Health





Cardiometabolic diseases such as cardiovascular disease and type 2 diabetes have emerged as some of the key drivers of worsening mortality rates in the United States over the last 15 years. People with limited education are feeling the brunt of this crisis, according to a new study by Boston University School of Public Health (BUSPH), the University of Helsinki, and the University of Minnesota.

For both men and women without a Bachelor’s degree (BA), mortality between 2011-2023 was markedly higher than would have been expected had death rates from 2006-2010 continued. Among 564,855 excess deaths in 2023 alone, 481,211 occurred among people without a BA—a 26 percent increase in mortality among this population, compared to pre-2010 trends. In contrast, mortality only increased by eight percent among people who received a BA. The study was published in JAMA Health Forum.

"While much attention has focused on how the COVID-19 pandemic led to life expectancy declines and excess mortality, our study shows that the United States was already experiencing an increasing number of excess deaths before the pandemic," says study lead author Dr. Eugenio Paglino, postdoctoral researcher at the Helsinki Institute for Demography and Population Health at the University of Helsinki. "The pandemic further exacerbated these trends, with excess deaths peaking in 2021. However, even after COVID-19 mortality declined in 2023, excess deaths remained substantially higher than in the pre-pandemic period, highlighting the importance of looking at long-term mortality trends to uncover the mechanisms behind current developments."

The findings underscore the urgent need to address cardiometabolic health and chronic diseases nationwide, particularly the social and structural factors that might explain why people with less education disproportionately experience these adverse health outcomes. 

“The United States is facing a crisis of deteriorating mortality that is largely falling on the shoulders of those with less education,” says study senior and corresponding author Dr. Andrew Stokes, associate professor of global health at BUSPH. “Living in rural areas, having a lack of access to healthy foods and good nutrition, working in precarious employment sectors—these are the things that make it difficult to eat well, sleep well, and exercise. Education fundamentally structures people’s work opportunities, and having less of it sets people up for a lot of downstream consequences that make it difficult to maintain good health.”

For the study, Dr. Stokes and colleagues from the University of Helsinki and the University of Minnesota utilized national mortality and education data to examine 47, 545, 611 deaths among US adults ages 35 and older from 2006-2023, categorizing 2011-2023 as the pre-pandemic, pandemic, and post-pandemic periods.

While less pronounced, circulatory diseases were also the leading cause of excess deaths among adults with a BA or equivalent degree.

"Despite decades of progress in prevention and treatment, cardiovascular diseases (including heart disease and stroke) remain the leading causes of death and major disability in the US and worldwide," says Dr. Donald Lloyd-Jones, director of Boston University's Framingham Center for Population and Prevention Science and primary investigator of the Framingham Heart Study, the longest-running heart disease study in the US. Dr. Lloyd-Jones, who is also the Alexander Graham Bell Professor and section chief of preventive medicine and epidemiology at BU Chobanian & Avedisian School of Medicine, was not involved in the study. "We know that the social drivers of health, including socioeconomic position, neighborhood environment, and, especially education, have a major impact on the predisposing risk factors for cardiovascular disease such as adverse diet, obesity, diabetes, blood pressure, and blood lipids. These findings reinforce and quantify the role that education can play in equipping people to manage their health and extend their longevity."

Diabetes was also a top 2023 contributor to excess deaths among men and women without a BA, and to a lesser extent, those with a BA. The researchers cite a range of factors that have led to an increase in unhealthy food consumption, from effective marketing and advertising of ultra-processed foods to a lack of access to affordable, nutrient-dense foods.

Of note, the findings also showed that drug overdoses were a significant contributor to excess deaths among men with less education, but were much less pronounced among men with more education. 

“This observation reflects the downstream consequences of prescription drug use, which led to widespread drug reliance and overdose in the early 2000s, before translating into the use of heroin, fentanyl, and other products that were more readily available during that period,” Dr. Stokes says. “The fact that drug poisonings were still a major cause of excess deaths for men without a BA in 2023 points to the ongoing role of deaths of despair in US mortality.”

"This work is a clarion call for us to understand the health threats facing Americans with less education," says Dr. Maria Glymour, chair and professor of epidemiology at BUSPH, who was not involved in the study but has studied how education is a predictor of health. “The mortality differences reported here suggest that we need to consider the 'causes of the causes' of social inequalities. History demonstrates it is possible to either shrink or magnify these disparities via public health and policy actions."

The researchers did observe a few promising trends in mortality. Among women with a BA, deaths due to cancer and other external causes (such as accidents and violence) decreased in 2023, compared to totals between 2006-2010.

“If we had simply maintained the progress we were making for each of these education groups 20 years ago, there are half a million Americans who died in 2023 who wouldn't have died,” says study coauthor Dr. Elizabeth Wrigley-Field, associate professor of sociology at the University of Minnesota, Twin Cities. “Almost 92 percent of them didn't have a college degree. The fact that the causes of these deaths span such different causes, including cardiovascular diseases, drug overdoses, and diabetes, tells us that there is a really deep divide in who benefits from health progress.”

One of the most important ways in which education matters is the kind of work it gives people access to, she adds. “We hope these results will contribute to a conversation about the ways that American workplaces aren't always conducive to good health, and what would allow American workers to live longer lives.”

** 

About Boston University School of Public Health 

Founded in 1976, Boston University School of Public Health is one of the top ten ranked schools of public health in the world. It offers master's- and doctoral-level education in public health. The faculty in six departments conduct policy-changing public health research around the world, with the mission of improving the health of populations—especially the disadvantaged, underserved, and vulnerable—locally and globally.

 

Reef fish population growing off Alabama coast



University of South Alabama fish survey shows a healthy red snapper population in Alabama waters




University of South Alabama





The reef fish population in the Gulf is growing ahead of the 2025 red snapper season according to the University of South Alabama’s annual fish survey. 

Researchers from the Stokes School of Marine and Environmental Sciences recently completed their annual presentation to the leadership at Alabama Marine Resources Division on the condition of fish populations around the more than 10,000 artificial reefs off Alabama’s coast. Although the average size of red snapper is lower than some points in the time series, numbers of red snapper are higher than at any recent years.

The survey includes deploying an underwater remotely operated vehicle with a camera to collect imagery of fish swimming in Gulf waters to help estimate the population. In 2024, they observed the highest value of red snapper since the survey began in 2011.

The survey includes deploying an underwater remotely operated vehicle with a camera to collect imagery of fish swimming in Gulf waters to help estimate the population. Coupled with bottom habitat mapping to estimate the number of artificial and natural reefs, these data allow USA researchers to estimate population size and trends.

“We have a healthy red snapper population in our area of the Gulf,” said Dr. Sean Powers, director of the Stokes School of Marine and Environmental Sciences. “We have the management and science in place to balance the needs of a diverse group of fishermen.”

The 2025 red snapper season will open to private and state-licensed charter vessel anglers beginning Friday, May 23. It will remain open seven days a week through June 30. The season will then transition to four-day weekends starting July 4 until the private angler quota is met. The Alabama private angler quota for 2025 is set by National Oceanic and Atmospheric Administration Fisheries and is anticipated to be 664,552 pounds.

“Alabama is blessed with phenomenal fishery resources,” Alabama Department of Conservation and Natural Resources Commissioner Chris Blankenship said. “Our partnership with the University of South Alabama to provide cutting edge-based fishery research as well as long-term data collection is critical in assisting us in making informed decisions.”

The daily bag limit is two red snapper per person, per day with a minimum size limit of 16 inches.

Anglers 16 years of age and older must have an Alabama saltwater fishing license (resident or non-resident, annual or trip), and any Alabama resident 65 or older or a lifetime saltwater license holder must have a current saltwater angler registration.

This research was partially funded by the Federal Aid in Sport Fish Restoration Program, Office of Conservation Investment via multiple grant awards administered by the Alabama Department of Conservation and Natural Resources, Marine Resources Division, National Fish and Wildlife Foundation, and Alabama saltwater anglers through their purchase of the Reef Fish


Science and innovation for a sustainable future



At VivaTech in Paris, research center coordinators showcase the advances made at the University of São Paulo in agriculture, climate, energy, computing, artificial intelligence, and health.



 News Release 

Fundação de Amparo à Pesquisa do Estado de São Paulo

Science and innovation for a sustainable future 

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From left to right, Vanderlei Bagnato, Marcelo Zuffo, Fabio Cozman, Carlos Labate, Paulo Artaxo and Julio Meneghini 

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Credit: Heitor Shimizu/Agência FAPESP




The University of São Paulo (USP) and FAPESP are participating in the 9th edition of Viva Technology (VivaTech), Europe’s largest startup and technology event. They have a 100-square-meter stand to showcase innovations in agriculture, climate, energy, artificial intelligence, and health (read more at: agencia.fapesp.br/54959).

The program at the stand also includes USP professors who, besides being available to investors, entrepreneurs, and visitors to the fair, are participating in roundtable discussions to present technologies developed by their centers of excellence.

One of the round tables was themed “Science and Innovation for a Sustainable Future: USP Advances in Climate, AI, Clean Energy, Health, and Technology,” and featured the following speakers: Julio MeneghiniPaulo ArtaxoCarlos LabateMarcelo ZuffoFabio Cozman, and Vanderlei Bagnato.

Meneghini discussed some of the projects and innovations presented at VivaTech by the Research Center for Greenhouse Gas Innovation (RCGI), a research center based at the Engineering School (POLI-USP) and funded by Shell and FAPESP. The RCGI was responsible for organizing the institutional participation of USP and FAPESP in the Paris event, including stand design, technology curation, and activity programming.

“We brought some examples of innovations produced at the RCGI, such as startups involved in green methanol production, solar-powered hydrogen production, solid oxide fuel cells, and ethanol-powered electricity generation. We’re also presenting a system that uses virtual reality to produce a multisensory experience simulating the Amazon Rainforest with visual, auditory, and olfactory stimuli,” he said.

“The RCGI is celebrating its tenth anniversary, and it’s very satisfying to see the results of important projects developed during this period by the approximately 600 researchers who are part of the project. Our center was created with support from FAPESP under the Engineering Research Centers/Applied Research Centers Program, and our mission is to become a globally recognized center of excellence that contributes to a sustainable future and helps Brazil meet its climate goals established in the Paris Agreement,” said Meneghini.

The RCGI’s executive and scientific director emphasized that the focus is on producing practical solutions based on solid science. One of the programs mentioned was Greenhouse Gases, with projects aimed, for example, at reducing leaks of methane – one of the most potent greenhouse gases – in industrial processes.

“Another RCGI program is Nature-Based Solutions, through which we seek to develop new technologies applicable to agriculture and livestock, making these sectors more sustainable,” said Meneghini.

“At the RCGI, we also have a cross-cutting project that seeks to focus the center’s internationalization efforts, as we believe that Brazil can lead the next great challenge of this century: making progress happen in a sustainable way,” he said.

Paulo Artaxo presented a project aimed at building a greenhouse gas emissions database for the Amazon region, which is also being conducted at the RCGI. The platform is being built using big data techniques to generate information that will enable the monitoring of emissions, a more accurate understanding of their causes, and support for the formulation of public policies aimed at mitigating these gases.

“Initially focused on the Amazon, the project is now being expanded to all of South America. Among the main features of the platform are a harmonized database and a user-friendly interface. All of this provides a solid scientific basis for decision makers to act more safely and effectively,” said Artaxo.

Cerrado solution

Carlos Labate, coordinator of the Multi-user Proteomics, Metabolomics, and Lipidomics Laboratory at the Luiz de Queiroz School of Agriculture (ESALQ-USP), gave a presentation on macaúba as a promising crop for sustainable development. In partnership with Acelen Renováveis, ESALQ-USP researchers are developing a project to produce biofuels from macaúba, a plant native to the Cerrado (Brazilian savanna-like biome) that has not yet been domesticated.

“Macaúba stands out for its extremely high oil productivity – it produces seven to ten times more oil than soybeans – and it’s important to note that it isn’t a food crop, meaning it doesn’t compete with crops such as soybeans or corn. This eliminates one of the main criticisms of using agricultural land for biofuel production: we aren’t taking space away from food production,” said Labate.

The goal of the project is to produce sustainable aviation fuel and renewable diesel. According to the professor, Brazil has a significant amount of land with agricultural potential, and macaúba is a sustainable way to utilize it. “Managing macaúba using degraded pastures won’t encourage deforestation or negatively impact land use,” he said.

The ESALQ-USP professor explained that they are studying three species of macaúba: Acrocomia aculeata, distributed mainly in the states of Bahia and Minas Gerais and in the southern region of the state of Mato Grosso; Acrocomia totai, present in the states of Mato Grosso and Mato Grosso do Sul; and Acrocomia intumescens, found mainly in the Northeast region of Brazil. “This diversity represents multiple opportunities for regional development, with species adapted to different environments, from the coast to the interior of the country. We’ve already sequenced the genome of A. aculeata and are finalizing the sequencing of A. totai. This work is fundamental for the genetic improvement of the plant,” he said.

The researchers are building a germplasm bank using samples collected from different regions. These samples show genetic variability in characteristics such as fruit size and quantity, which are essential factors for developing more productive varieties.

A trillion computers

The goal of the project presented by Marcelo Zuffo, coordinator of the Interdisciplinary Center for Interactive Technologies at USP, is to develop a real-time perception of the Amazon Rainforest through a new type of artificial intelligence.

“Our main challenge is to build a persistent perception of the biodiversity of the rainforest – a perception that’s accurate, direct, continuous, and long-lasting. It’s important to remember that many trees in tropical forests live for centuries, while most electronic devices today don’t even last a few decades,” he said.

The project, called Farm AI, proposes developing autonomous devices equipped with carbon dioxide, temperature, infrared, and other sensors. These sensors must operate safely, efficiently, and autonomously in remote environments. The researchers are also using technologies such as blockchain and encryption to ensure the security, traceability, and integrity of the data collected.

“What’s our vision? A trillion computers. We work with the concept of dust computing. Imagine computational grains of sand scattered throughout the Amazon – a simple handful of this sand containing billions of grains, each capable of processing data, communicating, and collaborating with others,” said Zuffo.

The researcher commented that the next big technological wave may be in such devices, which are embedded everywhere and capable of interacting, collaborating, and replicating themselves. “Intelligent devices interacting organically, creating a distributed collective intelligence – for example, a collective organic intelligence of the forest – leading to an internet of trees,” he said.

“We already have working prototypes. The idea is to create a swarm of robust, very low-cost devices with environmental sensor applications. We’ve already conducted the first tests, with ten devices launched in the forest, and we plan to produce 2,000 units,” he said.

Zuffo explains that each device is coin-sized and contains a 2 x 3 millimeter chip with 300 million transistors. “It’s a complete computer capable of running AI and encryption, and can connect to more than 200 different sensors,” he said.

Preserving Indigenous languages

For decades, USP has been a national reference in artificial intelligence research, conducting studies in various fields and units, including medicine, engineering, computer science, and social sciences. To consolidate this work, the Center for Artificial Intelligence (C4AI) was created as a partnership between USP, FAPESP, and IBM. The center brings together about 90 professors from various fields, explained Fabio Cozman, the director of the center.

“At the C4AI, we investigate everything from AI algorithms to their practical applications in sectors such as health, law, public policy, agribusiness, and natural language processing, with an emphasis on the Portuguese language,” said Cozman, who highlighted two C4AI projects focused on sustainability, which was the theme of the session at VivaTech.

“In the first, the idea is to predict extreme events in the South Atlantic, particularly studying storm surges, which cause flooding due to tides and winds rather than rain. The project uses a machine learning approach based on physical models that integrates ocean data with environmental modeling, in collaboration with researchers in engineering and marine sciences,” he said.

“The second project focuses on preserving Brazilian indigenous languages to ensure their continuity among new generations. The challenge lies in developing translation tools for Brazil’s indigenous languages. The country has more than 200 languages besides Portuguese. The proposal is to create applications and tools that help young people learn and become familiar with their language and their ancestral language,” said Cozman.

Photonics against bacterial resistance

“At the University of São Paulo, we work with three fundamental principles: doing science with excellence; doing science with relevance – that is, solving problems, especially with social responsibility; and third, being international. We don’t produce knowledge just for ourselves, but for humanity. That’s what we’re proud of,” said Vanderlei Bagnato, coordinator of the Optics and Photonics Research Center (CePOF) at the São Carlos Institute of Physics (IFSC-USP).

“In São Carlos, we have about 120 people working. We started as a center funded by FAPESP, and today we’re also part of a federal government program, with projects co-funded by companies. We currently have around 90 projects with the private sector – 60 already completed and 30 in progress. Our team is multidisciplinary: physicists, doctors, pharmacists, mathematicians – we work with technology development and instrumentation, from quantum physics to healthcare,” he explained.

“We work in human, environmental, and animal health, facing three major challenges. The first is cancer treatment. Despite advances in knowledge, access to treatment is still very limited – even in rich countries, the costs are extremely high. The second challenge is chronic diseases such as Parkinson’s, diabetes, fibromyalgia, and arthritis, which affect millions of people and require new protocols and equipment to improve patients’ quality of life,” said Bagnato.

“The third major challenge is infections, especially given the bacterial resistance to antibiotics. We’re developing an innovative treatment for resistant pneumonia: we’ve created inhalable molecules that attach themselves to the lungs at the site of infection and are activated by infrared light. This generates free radicals that destroy the bacterial colony or make the bacteria sensitive to antibiotics again,” said the CePOF coordinator.

“We’re already in phase 3 of clinical trials for this treatment. In Texas, we’re developing animal models of pneumonia in sheep and dogs – species that naturally develop the disease. We hope to begin clinical trials in humans next year. This approach could be a game changer because 10 to 15 million people die from resistant pneumonia each year, not due to a lack of doctors, but due to a lack of effective drugs,” said Bagnato. He is partnering with Texas A&M University to establish a CePOF-style center in the United States with funding from the State of Texas.

FAPESP’s participation in VivaTech is part of the FAPESP Week France program. For more information, visit: fapesp.br/week/2025/france

 

Strange radio pulses detected coming from ice in Antarctica




Penn State
a range of instruments flown on balloons high above Antarctica 

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The unusual radio pulses were detected by the Antarctic Impulsive Transient Antenna (ANITA) experiment, a range of instruments flown on balloons high above Antarctica that are designed to detect radio waves from cosmic rays hitting the atmosphere. 

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Credit: Stephanie Wissel / Penn State




UNIVERSITY PARK, Pa. — A cosmic particle detector in Antarctica has emitted a series of bizarre signals that defy the current understanding of particle physics, according to an international research group that includes scientists from Penn State. The unusual radio pulses were detected by the Antarctic Impulsive Transient Antenna (ANITA) experiment, a range of instruments flown on balloons high above Antarctica that are designed to detect radio waves from cosmic rays hitting the atmosphere.

The goal of the experiment is to gain insight into distant cosmic events by analyzing signals that reach the Earth.  Rather than reflecting off the ice, the signals — a form of radio waves — appeared to be coming from below the horizon, an orientation that cannot be explained by the current understanding of particle physics and may hint at new types of particles or interactions previously unknown to science, the team said. 

The researchers published their results in the journal Physical Review Letters.

“The radio waves that we detected were at really steep angles, like 30 degrees below the surface of the ice,” said Stephanie Wissel, associate professor of physics, astronomy and astrophysics who worked on the ANITA team searching for signals from elusive particles called neutrinos.

She explained that by their calculations, the anomalous signal had to pass through and interact with thousands of kilometers of rock before reaching the detector, which should have left the radio signal undetectable because it would have been absorbed into the rock.

“It’s an interesting problem because we still don't actually have an explanation for what those anomalies are, but what we do know is that they're most likely not representing neutrinos,” Wissel said.

Neutrinos, a type of particle with no charge and the smallest mass of all subatomic particles, are abundant in the universe. Usually emitted by high-energy sources like the sun or major cosmic events like supernovas or even the Big Bang, there are neutrino signals everywhere. The problem with these particles, though, is that they are notoriously difficult to detect, Wissel explained.

“You have a billion neutrinos passing through your thumbnail at any moment, but neutrinos don't really interact,” she said. “So, this is the double-edged sword problem. If we detect them, it means they have traveled all this way without interacting with anything else. We could be detecting a neutrino coming from the edge of the observable universe.”

Once detected and traced to their source, these particles can reveal more about cosmic events than even the most high-powered telescopes, Wissel added, as the particles can travel undisturbed and almost as fast as the speed of light, giving clues about cosmic events that happened lightyears away. 

Wissel and teams of researchers around the world have been working to design and build special detectors to capture sensitive neutrino signals, even in relatively small amounts. Even one small signal from a neutrino holds a treasure trove of information, so all data has significance, she said.

“We use radio detectors to try to build really, really large neutrino telescopes so that we can go after a pretty low expected event rate,” said Wissel, who has designed experiments to spot neutrinos in Antarctica and South America.

ANITA is one of these detectors, and it was placed in Antarctica because there is little chance of interference from other signals. To capture the emission signals, the balloon-borne radio detector is sent to fly over stretches of ice, capturing what are called ice showers.

“We have these radio antennas on a balloon that flies 40 kilometers above the ice in Antarctica,” Wissel said. “We point our antennas down at the ice and look for neutrinos that interact in the ice, producing radio emissions that we can then sense on our detectors.”

These special ice-interacting neutrinos, called tau neutrinos, produce a secondary particle called a tau lepton that is released out of the ice and decays, the physics term referring to how the particle loses energy as it travels over space and breaks down into its constituents. This produces emissions known as air showers.

If they were visible to the naked eye, air showers might look like a sparkler waved in one direction, with sparks trailing it, Wissel explained. The researchers can distinguish between the two signals — ice and air showers — to determine attributes about the particle that created the signal. 

These signals can then be traced back to their origin, similar to how a ball thrown at an angle will predictably bounce back at the same angle, Wissel said. The recent anomalous findings, though, cannot be traced back in such a manner as the angle is much sharper than existing models predict.

By analyzing data collected from multiple ANITA flights and comparing it with mathematical models and extensive simulations of both regular cosmic rays and upward-going air showers, the researchers were able to filter out background noise and eliminate the possibility of other known particle-based signals.

The researchers then cross-referenced signals from other independent detectors like the IceCube Experiment and the Pierre Auger Observatory to see if data from upward-going air showers, similar to those found by ANITA, were captured by other experiments.

Analysis revealed the other detectors did not register anything that could have explained what ANITA detected, which led the researchers to describe the signal as “anomalous,” meaning that the particles causing the signal are not neutrinos, Wissel explained. The signals do not fit within the standard picture of particle physics, and while several theories suggest that it may be a hint of dark matter, the lack of follow-up observations with IceCube and Auger really narrow the possibilities, she said.

Penn State has built detectors and analyzed neutrino signals for close to 10 years, Wissel explained, and added that her team is currently designing and building the next big detector. The new detector, called PUEO, will be larger and better at detecting neutrino signals, Wissel said, and it will hopefully shed light on what exactly the anomalous signal is.

“My guess is that some interesting radio propagation effect occurs near ice and also near the horizon that I don't fully understand, but we certainly explored several of those, and we haven't been able to find any of those yet either,” Wissel said. “So, right now, it's one of these long-standing mysteries, and I'm excited that when we fly PUEO, we'll have better sensitivity. In principle, we should pick up more anomalies, and maybe we'll actually understand what they are. We also might detect neutrinos, which would in some ways be a lot more exciting.”

The other Penn State co-author is Andrew Zeolla, a doctoral candidate in physics. The research conducted by scientists from Penn State was funded by the U.S. Department of Energy and the U.S. National Science Foundation. The paper contains the full list of collaborators and authors.

ANITA was placed in Antarctica because there is little chance of interference from other signals. To capture the emission signals, the balloon-borne radio detector is sent to fly over stretches of ice, capturing what are called ice showers. 

Stephanie Wissel and teams of researchers around the world have been working to design and build special detectors to capture sensitive neutrino signals, even in relatively small amounts. Even one small signal from a neutrino holds a treasure trove of information, so all data has significance, she said. 

Credit

Stephanie Wissel / Penn State

 

Amazon trees under pressure: New study reveals how forest giants handle light and heat



Michigan State University





Images

Why this matters:

  • Scientists use satellite images of light given off by plants — called solar-induced fluorescence, or SIF — to check how healthy the Amazon forest is. SIF is often used to estimate how much photosynthesis is happening. But this study shows that SIF may not be a reliable predictor of photosynthesis functionality. When the climate is stressful, like during a drought, leaves might still glow more even though their ability to photosynthesize is diminished. This could lead scientists to think the forest is doing better than it really is.
  • The findings offer a first-of-its-kind, high-resolution look at how the Amazon canopy navigates seasonal extremes.
  • Understanding how trees manage light energy is important worldwide, as the Amazon plays a vital role in global climate regulation, recycling moisture into rainfall and storing vast amounts of carbon. 

EAST LANSING, Mich. – In a recent study published in New Phytologist, researchers at Michigan State University have uncovered how Amazon rainforest canopy trees manage the intense sunlight they absorb — revealing resilience to hot and dry conditions in the forest canopy while also offering a way to greatly improve the monitoring of canopy health under increasing extreme conditions. The study was made possible by funding from the National Science Foundation and NASA.

 

The study, led by doctoral candidate Leonardo Ziccardi with Associate Professor Scott Stark in the MSU Department of Forestry, shows how tropical trees act like giant solar antennas — absorbing vast quantities of light energy that must be carefully managed. When trees absorb more energy than they can use for photosynthesis, it must be safely dissipated, either as heat or re-emitted as light — a process called chlorophyll fluorescence.

“It’s been a long journey,” said Ziccardi. “Since 2019, we’ve run multiple field campaigns across seasons, climbing giant trees in the heart of the Amazon to understand how these forests respond to environmental changes. We’ve spent hundreds of hours up in the canopy doing measurements —some of the most intense and rewarding work I’ve ever done.”

Ziccardi spent more than four years climbing trees nearly 200 feet tall in the central Amazon, measuring the fates of absorbed photons in thousands of leaves across many species, canopy heights, and light exposure conditions, producing a truly unique and unprecedented dataset.

Using a revolutionary handheld instrument — the MultispeQ, developed at MSU by co-author David Kramer in the MSU-DOE Plant Research Laboratory — Ziccardi captured how leaves in natural settings balance incoming light with their ability to photosynthesize or dissipate excess energy.

The findings offer a first-of-its-kind, high-resolution look at how the Amazon canopy navigates seasonal extremes. As the Amazon experiences increasing stress, due to both greenhouse gases and deforestation leading to hotter and drier conditions in the canopy, understanding how trees manage light energy is essential to predicting their future survival. Not only does this climate change lead to greater physiological stress due to more frequent extreme conditions related to lower soil water availability and dry and hot air, it also can increase the amount of sunlight hitting the forest. This happens because drier conditions have less clouds and that lets more sunlight through. This study helps address whether Amazon trees can absorb and use this extra light under stressful conditions. 

Despite facing intense sunlight and atmospheric dryness, many canopy leaves were able to continue photosynthesizing, but only by increasing their allocation to energy dissipation pathways. For the first time in the Amazon, the study revealed a nuanced, three-phase response of leaves to rising light and drought conditions. Under low to moderate light, leaves balance energy use between photosynthesis and fluorescence, so these processes tend to increase and decrease together. As light and drought stress increase, however, this balance breaks down. Heat-protective dissipation mechanisms become overwhelmed, photosynthesis drops, and fluorescence can spike — signaling potential damage to the photosynthetic machinery.

The implications are critical for scientists using satellite observations of fluorescence — the so-called solar-induced fluorescence, or SIF — to monitor Amazon forest health. While SIF is often used as a proxy for photosynthesis, this study shows that photosynthesis and fluorescence do not always go up and down together. Under high light and stress, this relationship breaks down and leaves may fluoresce more even as their photosynthetic machinery declines, potentially leading to overestimates of ecosystem productivity during droughts.

By Lauren Noel

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Michigan State University has been advancing the common good with uncommon will for 170 years. One of the world’s leading public research universities, MSU pushes the boundaries of discovery to make a better, safer, healthier world for all while providing life-changing opportunities to a diverse and inclusive academic community through more than 400 programs of study in 17 degree-granting colleges.

For generations, Spartans have been changing the world through research. Federal funding helps power many of the discoveries that improve lives and keep America at the forefront of innovation and competitiveness. From lifesaving cancer treatments to solutions that advance technology, agriculture, energy and more, MSU researchers work every day to shape a better future for the people of Michigan and beyond. Learn more about MSU’s research impact powered by partnership with the federal government. 

For MSU news on the web, go to MSUToday or x.com/MSUnews