U.S. forests are locking in major carbon emissions

Forest ecosystems help keep the environment stable as the amount of greenhouse gases released into the atmosphere increases.
Photo Credit: Andrew Coelho

Scientific Frontline: "At a Glance" Summary

• Main Discovery: U.S. forests have stored more carbon in the past two decades than at any time in the last century, a spike driven primarily by natural forces and forest aging rather than active human management.
• Methodology: Researchers analyzed nationwide forest data to isolate and quantify the specific contributions of six environmental drivers: temperature, precipitation, carbon dioxide, land management, forest age composition, and total area.
• Key Data: Forest aging contributed the largest share of sequestration at 89 million metric tons annually, while temperature and precipitation shifts added 66 million tons per year; in contrast, deforestation caused a loss of 31 million tons annually.
• Significance: Disentangling natural ecosystem functions from human interventions allows for accurate national carbon accounting, revealing that passive natural sinks are currently more significant than active decarbonization efforts in forests.
• Future Application: Policymakers can utilize these findings to refine national forest inventories for net-zero requirements and tailor forest management plans to specific regional climate adaptations.
• Branch of Science: Environmental Economics and Forestry
• Additional Detail: While tree planting and reforestation contributed 23 million tons of carbon storage per year, this figure was surpassed by the carbon losses resulting from human-caused deforestation.

Old diseases return as settlement pushes into the Amazon rainforest

Yellow fever cases have begun to rise, spilling over the expanding border between the forest and urban areas.
Photo Credit: Thiago Japyassu

Scientific Frontline: "At a Glance" Summary

• Main Discovery: The expansion of human settlements into the Amazon rainforest, specifically the growing interface between urban areas and forests, is the primary driver behind the recent resurgence of human yellow fever spillover cases.
• Methodology: Researchers analyzed yellow fever case records from Brazil (2000–2021), Colombia (2007–2021), and Peru (2016–2021) alongside land-use data from the MapBiomas Project, modeling the relationship between disease rates and geographic metrics such as forest patch size, edge density, and forest-urban adjacency.
• Key Data: A 10% increase in forest-urban adjacency raised the probability of a spillover event by 0.09, equivalent to a 150% increase in the number of spillover events annually; notably, this high-risk borderland is expanding by approximately 13% per year.
• Significance: Proximity between human settlements and forest edges is a significantly stronger predictor of disease spillover than ecological forest fragmentation alone, raising critical concerns that urban transmission cycles—independent of non-human hosts—could reemerge.
• Future Application: Findings indicate a critical need to realign public health infrastructure and vaccination stockpiles to specifically target expanding forest-urban interfaces, rather than relying solely on broad ecological conservation metrics.
• Branch of Science: Disease Ecology and Epidemiology
• Additional Detail: Recent data highlights the urgency, with confirmed yellow fever cases in 2025 showing a threefold increase compared to 2024 and shifting geographically to areas outside the Amazon basin.

Freshwater browning threatens growth and populations of economically important fish

Smallmouth bass
Image Credit: Scientific Frontline / stock image

Scientific Frontline: "At a Glance" Summary

• Main Discovery: Freshwater browning stunts the growth of specific fish species and alters community composition by favoring distinct traits, ultimately shifting population dynamics in north-temperate lakes.
• Methodology: Researchers synthesized data from 871 lakes across North America and Europe to analyze population trends and further examined a subset of 303 lakes to assess functional traits, such as eye size, in relation to water color gradients.
• Key Data: Browner waters correlated with increased abundance of northern pike and walleye but declines in lake trout, brook trout, yellow perch, largemouth and smallmouth bass, and whitefish; communities in darker waters were significantly more likely to feature species with large eyes.
• Significance: This phenomenon, driven by climate change and land use, disrupts aquatic food webs and creates cascading ecological effects that extend to terrestrial systems, such as altering the diets of birds dependent on specific fish populations.
• Future Application: These findings enable improved forecasting models for fisheries management, allowing for better prediction of ecosystem shifts and biodiversity loss under continuing browning scenarios.
• Branch of Science: Ecology and Limnology
• Additional Detail: The study confirms that freshwater browning is a widespread, transcontinental issue affecting biodiversity across North America and Europe, rather than a localized anomaly.

What Is: Invasive Species

Image Credit: Scientific Frontline / stock image

Scientific Frontline: Extended "At a Glance" Summary

The Core Concept: Invasive species are non-native organisms that, upon introduction to a new environment, escape the evolutionary checks of their native ranges to cause significant ecological, economic, or human health harm. This phenomenon represents a systemic disruption of biophysical systems rather than merely the presence of an unwanted plant or animal.

Key Distinction/Mechanism: The defining characteristic separating "invasive" from "non-native" is impact; while many non-native species (like agricultural crops) are beneficial, invasive species actively dismantle native ecosystems. They often succeed via the Enemy Release Hypothesis, flourishing because they have left behind natural predators and diseases, or through Priority Effects, such as leafing out earlier than native flora to monopolize resources.

Origin/History: While natural translocation has occurred for eons, the current crisis is driven by the "relentless engine of human globalization" in the Anthropocene. The concept is underscored by the "Ten Percent Rule," a statistical filter noting that roughly 10% of transported species survive, 10% of those establish, and 10% of those become destructive invaders.

Long-term pesticide exposure accelerates aging and shortens lifespan in fish

Notre Dame biologist Jason Rohr
Photo Credit: Barbara Johnston/University of Notre Dame

Scientific Frontline: "At a Glance" Summary

• Main Discovery: Chronic exposure to low levels of the pesticide chlorpyrifos accelerates biological aging and reduces lifespan in fish, occurring at concentrations previously considered safe and distinct from acute toxicity.
• Methodology: Researchers combined field studies of over 20,000 lake skygazer fish (Culter dabryi) across lakes with varying contamination levels in China with controlled laboratory experiments that exposed fish to chronic low doses (10 and 50 ng/L) over 16 weeks to verify causal links.
• Key Data: Fish exposed to these low concentrations exhibited significantly shortened telomeres (protective chromosome caps) and increased lipofuscin (cellular waste) accumulation; notably, these aging markers appeared at levels below current U.S. freshwater safety standards.
• Significance: This research challenges the prevailing regulatory assumption that chemicals are safe if they do not cause immediate death, revealing that "silent" cumulative damage can drive population declines through accelerated aging rather than acute poisoning.
• Future Application: Regulatory frameworks for chemical safety assessments may need to be overhauled to include long-term markers of biological aging rather than relying solely on short-term lethality tests.
• Branch of Science: Environmental Toxicology and Ecology
• Additional Detail: As telomere biology and aging mechanisms are highly conserved across vertebrates, the findings suggest that chronic low-level pesticide exposure could pose similar aging-related health risks to humans.

Study Finds Ocean Impacts Nearly Double Economic Cost of Climate Change

A mangrove in Laguna del Cacahuate, Tabasco, Mexico.
Photo Credit: Octavio Aburto

Scientific Frontline: "At a Glance" Summary

• Main Discovery: Integrating ocean-related damages into the social cost of carbon calculation nearly doubles the estimated global economic harm caused by carbon dioxide emissions.
• Methodology: Researchers developed a framework accounting for market use values (fisheries, trade), non-market values (health, recreation), and non-use values (biodiversity existence), then integrated these into an economic model calibrated to various greenhouse gas emission trajectories.
• Key Data: The social cost of carbon increases from $51 to $97.2 per ton—a 91% rise—with market damages alone projected to reach $1.66 trillion globally per year by 2100.
• Significance: This "blue" social cost of carbon assigns monetary values to previously overlooked ocean variables like coral reef degradation and coastal infrastructure damage, preventing these factors from being invisible in standard economic accounting.
• Future Application: Policymakers and private sector leaders can utilize this metric to refine cost-benefit analyses for environmental regulations, risk management strategies, and corporate emission damage assessments.
• Branch of Science: Environmental Economics and Oceanography
• Additional Detail: The study highlights a highly unequal distribution of economic impact, with islands and small economies facing disproportionate harm due to their reliance on seafood and vulnerability to sea-level rise.

How climate change contributed to the demise of the Tang dynasty

Climatic and sociocultural changes may have contributed significantly to the demise of the Tang dynasty by weakening border defenses.
Image Credit: Scientific Frontline

Scientific Frontline: "At a Glance" Summary

• Main Discovery: Hydroclimatic instability, characterized by extreme droughts and floods between 800 and 907 CE, functioned as a critical driver in the socio-political collapse of the Tang Dynasty.
• Methodology: Researchers reconstructed historical runoff behavior in the Yellow River basin by analyzing long-term tree-ring data archives to model local hydroclimatic trends during the 9th century.
• Specific Mechanism: Vulnerability to climate extremes was exacerbated by an agricultural shift from drought-resistant millet to water-intensive wheat and rice, resulting in uncompensated crop failures during dry periods.
• Systemic Consequences: Compounded by collapsed supply corridors, widespread malnutrition weakened northern border defenses and precipitated mass migration southward, destabilizing the empire's political structure.
• Significance: The study establishes a historical precedent for how environmental stressors, when intersecting with specific socio-cultural choices, can trigger irreversible tipping points in complex societal systems.

Plastic particles increase inflammation and cross barriers

Lukas Kenner, visiting professor, Department of Molecular Biology.
Photo Credit: Medizinische Universität Wien

Scientific Frontline: "At a Glance" Summary

• Core Discovery: Micro- and nanoplastics (MNPs) exacerbate chronic inflammatory bowel diseases (IBD) and penetrate biological barriers to accumulate in vital organs beyond the gastrointestinal tract.
• Methodology: Researchers utilized a mouse model of ulcerative colitis, orally administering polystyrene particles—a common plastic found in food packaging—to analyze molecular and histological interactions with the intestinal mucosa and immune system.
• Mechanism of Action: MNP exposure triggers pro-inflammatory activation of macrophages and induces gut dysbiosis, characterized by a decrease in beneficial bacterial species and an increase in potentially harmful, pro-inflammatory microbes.
• Data Point: Nanoplastic particles smaller than 0.0003 millimeters (0.3 micrometers) demonstrated the highest mobility, successfully traversing the intestinal barrier to deposit in the liver, kidneys, and bloodstream.
• Contextual Findings: The uptake of MNPs into the intestinal mucosa is significantly intensified during active inflammatory states, suggesting a feedback loop where existing inflammation facilitates further plastic accumulation.
• Primary Implication: MNPs are an underestimated environmental factor in the pathogenesis of chronic inflammatory diseases, highlighting an urgent need to evaluate the systemic health risks posed by the migration of the smallest particles into major organ systems.

New study reveals major gaps in global forest maps

A Copernicus Sentinel-2B satellite map of South Sudan shows the tropical forests, swamps and grassland that comprise the majority of the country's terrain.
Photo Credit: European Space Agency
(CC BY-SA 4.0)

Scientific Frontline: "At a Glance" Summary

• Global Dataset Discrepancy: A comparative analysis of eight major global forest datasets reveals that they concur on the identification of forest locations only 26% of the time, highlighting severe inconsistencies in digital baselines.
• Methodological Divergence: The study attributes these variations to differing technical definitions of "forest"—specifically regarding canopy cover thresholds (e.g., 10% vs. 50%)—and the specific remote sensing technologies employed to interpret land use.
• Socioeconomic Impact Data: In a specific case study of India, estimates of the population living in poverty near forests ranged dramatically from 23 million to 252 million, depending solely on the forest map utilized.
• Scale of Uncertainty: Definitional variances result in uncertainty factors of up to 10, capable of instantly reclassifying millions of hectares between "forest" and "non-forest" status in global inventories.
• Implications for Climate Policy: These discrepancies undermine the reliability of carbon storage estimates and nature-based markets, posing risks to the accurate allocation of climate finance and the validation of conservation policies.
• Proposed Resolution: The researchers introduced a decision-support flowchart to assist stakeholders in dataset selection and advocated for hybrid models that validate satellite imagery with ground-level data to improve accuracy.

How light reflects on leaves may help researchers identify dying forests

Trees at UNDERC
Photo Credit: Barbara Johnston/University of Notre Dame

Early detection of declining forest health is critical for the timely intervention and treatment of droughted and diseased flora, especially in areas prone to wildfires. Obtaining a reliable measure of whole-ecosystem health before it is too late, however, is an ongoing challenge for forest ecologists.

Traditional sampling is too labor-intensive for whole-forest surveys, while modern genomics—though capable of pinpointing active genes—is still too expensive for large-scale application. Remote sensing offers a high-resolution solution from the skies, but currently limited paradigms for data analysis mean the images obtained do not say enough, early enough.

A new study from researchers at the University of Notre Dame, published in Nature: Communications Earth & Environment, uncovers a more comprehensive picture of forest health. Funded by NASA, the research shows that spectral reflectance—a measurement obtained from satellite images—corresponds with the expression of specific genes.

Reflectance is how much light reflects off of leaf material, and at which specific wavelengths, in the visible and near-infrared range. Calculated as the ratio of reflected light to incoming light and measured using special sensors, reflectance data reveals a unique signature specific to the leaf’s composition and condition.

Arctic has entered a new era of extreme weather

Cassiope tetragona killed by a rain-on-snow event.
Photo Credit: R Treharne

Extreme weather events have become significantly more common in the Arctic over recent decades, posing a threat to vital polar ecosystems, according to new research by an international team of scientists. 

Key Takeaways:

• New research by an international team of scientists has found that Arctic regions are facing unprecedented climate conditions 

• Study has found that extreme weather events have become more common over the past 30 years, threatening plants and animals 

• Findings show hotspots for extreme weather events are Western Scandinavia, the Canadian Arctic Archipelago and Central Siberia 

• Damage from extreme weather can also affect the livelihoods of Arctic people such as reindeer herders and may also harm the ability of the Arctic to absorb carbon and slow climate change. 

Extreme weather events have become significantly more common in the Arctic over recent decades, posing a threat to vital polar ecosystems, according to new research by an international team of scientists. 

Oil residues can travel over 5,000 miles on ocean debris, study finds

Petroleum residues can survive long-distance transport by adhering to floating debris, dramatically extending how far oil pollution can travel in the marine environment.
Photo Credit: Diane Buhler, Friends of Palm Beach

When oily plastic, glass, and rubber washed ashore on Florida beaches in 2020, it appeared at first to be a local mystery. But through a collaboration that paired community observations with world-leading oceanographic and chemical expertise, scientists traced the contamination across more than 5,200 miles of ocean.

In a new study published in ACS Environmental Science & Technology, researchers from Woods Hole Oceanographic Institution (WHOI) and Northeastern University, in collaboration with community scientists from Friends of Palm Beach, show that petroleum residues can survive long-distance transport by adhering to floating debris, dramatically extending how far oil pollution can travel in the marine environment.

Using advanced ocean current modeling and chemical fingerprinting developed at WHOI, the team linked the Florida debris to a massive oil spill that occurred along Brazil’s coastline in 2019.

“This study demonstrates how plastic pollution fundamentally changes the fate of oil in the ocean,” said Chris Reddy, chemical oceanographer at WHOI and a global authority on oil spill forensics. “By hitchhiking on debris, petroleum residues can persist and move far beyond what we previously believed possible.”

Recovering reef fish populations could nourish millions of additional people each year

A new study led by King Abdullah University of Science and Technology (KAUST) Assistant Professor Jessica Zamborain-Mason shows that rebuilding depleted coral reef fish populations could significantly increase sustainable food supplies for millions of people worldwide. Published in Proceedings of the National Academy of Sciences (PNAS), the work provides the first global quantification of how much food is currently being lost due to degraded reef fish stocks and how much can be regained if reefs are restored to sustainable levels.

Drawing on one of the largest coral reef datasets assembled to date, the study analyzes more than 1,200 reef sites across 23 tropical jurisdictions. The findings come at a critical moment: reef ecosystems are experiencing widespread climate-driven impacts, and if reef fisheries are overexploited, ecosystem resilience and tropical food systems are at risk.  

“Our study provides clear, quantitative evidence of how much food tropical coastal communities are losing — and could regain — through sustainably managed reef fisheries,” said Zamborain-Mason. “These insights give governments the scientific foundation needed to strengthen food security and ecosystem resilience through effective fisheries management.” 

How a persistent chemical enters our surface waters

Image Credit: Scientific Frontline / stock image

PFAS, short for per- and polyfluoroalkyl substances, are not called “forever chemicals” for nothing. These fluorine-containing organic molecules are difficult to break down and are likely to remain in the environment for decades or even centuries, where they can accumulate in humans and animals and may have harmful effects on health. This is a compelling reason to take precautionary measures. 

The PFAS class of substances comprises thousands of chemical compounds. Not all of them have been thoroughly studied. The release, spread, accumulation, and effects of numerous PFAS are the subject of ongoing research. Among other things, researchers are focusing on TFA, short for trifluoroacetic acid. The smallest molecule in the PFAS family is formed as a degradation product of various other substances, such as many fluorinated refrigerants and propellants. Once formed, TFA is hardly degraded in the environment. “TFA formed in the atmosphere quickly enters precipitation, and from there it travels into surface waters and then into groundwater,” says Empa researcher Stefan Reimann from the Air Pollutants / Environmental Technology laboratory. 

Scientists discover what drives California's worst fire years

Two natural resource specialists walk through an area of Redwood Mountain Grove burned in the KNP Complex Fire in California’s Sierra Nevada Mountains to evaluate fire effects.
Photo Credit: National Park Service

What makes one fire season worse than another in fire-prone parts of the world like California is poorly understood, but in a new study, scientists at the University of California, Irvine reveal how clusters of lightning-ignited fires called fire complexes are the chief drivers of the most destructive fire years. It’s a finding that could help agencies better manage such fires when they occur.

“Nobody has ever looked into these kinds of fires before,” said Rebecca Scholten, a postdoctoral fellow in Earth system science and lead author of the Science Advances study. “We theorized that when two or more fires in a fire complex merge, they would just burn themselves out. But we found the opposite – the fires grow worse.”

What Is: The Anthropocene

Image Credit: Scientific Frontline / stock image

At a Glance

• The Core Concept: The Anthropocene, or "Age of Man," is a proposed geological epoch positing that human activity has superseded natural forces to become the primary driver of Earth's geological and ecological systems.
• Key Distinction/Mechanism: Unlike the Holocene—the stable epoch of the last 11,700 years that fostered human civilization—the Anthropocene represents a fundamental rupture in Earth's history where humanity operates as a geological force rather than merely a biological one. It is characterized by the human-driven alteration of the atmosphere, hydrosphere, cryosphere, and biosphere, shifting the planet into a volatile and unstable interval.
• Origin/History: The term was popularized by atmospheric chemist Paul Crutzen at the turn of the millennium (c. 2000) to describe the profound impact of humanity on the planet.

Major Frameworks/Components

• A Diachronous "Event": The scientific community increasingly views the Anthropocene not strictly as a defined epoch with a singular start date (a "golden spike"), but as an unfolding, diachronous geological event comparable to the Great Oxidation Event.
• Planetary Health Indicators: The framework highlights critical shifts such as the disruption of nitrogen and phosphorus cycles, rapid ocean acidification, and accelerating species extinction.
• Stratigraphic Alteration: The concept suggests that humanity has fundamentally altered the physical stratigraphic record of the Earth.
• Why It Matters: The Anthropocene redefines the current environmental crisis not as a series of isolated issues, but as a systemic transformation of the Earth caused by a single species. It serves as the dominant conceptual framework for understanding planetary instability and signals that the conditions necessary for known civilization are ending.

Study finds exposure to common air pollutants alters adolescent brain development

For the first time, researchers at OHSU evaluated the long-term impact of air pollution on adolescent brain health and development.
Image Credit: Scientific Frontline / AI generated

Physician-scientists at Oregon Health & Science University warn that exposure to air pollution may have serious implications for a child’s developing brain.

In a recent study published in the journal Environmental Research, researchers in OHSU’s Developmental Brain Imaging Lab found that air pollution is associated with structural changes in the adolescent brain, specifically in the frontal and temporal regions — the areas responsible for executive function, language, mood regulation and socioemotional processing.

Air pollution causes harmful contaminants, such as particulate matter, nitrogen dioxide and ozone, to circulate in the environment. It has been exacerbated over the past two centuries by industrialization, vehicle emissions, and, more recently, wildfires.

Exposure to PFAS and PCBs linked to higher odds of MS

Aina Vaivade and Kim Kultima have measured the levels of common environmental pollutants in the blood of people with MS using a mass spectrometer (pictured).
Photo Credit: Tobias Sterner/Uppsala University

People who have been exposed to both PFAS and PCBs are more likely to be diagnosed with multiple sclerosis (MS). These new research findings are based on analyses of blood samples from more than 1,800 individuals in Sweden, one of the most comprehensive studies to date on the influence of chemical environmental exposure on the development of MS. 

Multiple sclerosis (MS) is an autoimmune disease in which both genetic and environmental factors can contribute to the risk of the disease. In the current study, researchers analyzed blood from individuals who had recently been diagnosed with MS to investigate concentrations of the common environmental contaminants PFAS and PCBs. 

Storms in the Southern Ocean mitigates global warming

Visible satellite image showing storms sweeping across the Southern Ocean on 4 January 2019.
Photo Credit: NASA Worldview Snapshot

Intense storms that sweep over the Southern Ocean enable the ocean to absorb more heat from the atmosphere. New research from the University of Gothenburg shows that today’s climate models underestimate how storms mix the ocean and thereby give less reliable future projections of our climate. 

The Southern Ocean is a vast expanse of ocean encircling the Antarctic continent, regulating Earth’s climate by moving heat, carbon, and nutrients out in the world’s oceans. 

It provides a critical climate service by absorbing over 75 per cent of the excess heat generated by humans globally. The Southern Ocean’s capacity to reduce climate warming depends on how efficiently it can absorb heat from our atmosphere.  

Biodegradable wet wipes remain in rivers for more than five weeks

Photo Credit: Christine Sandu

Scientists have tested, for the first time, how biodegradable wet wipes break down when flushed rather than composted discovering that most wipes remain after five weeks – a finding the research team says challenges the marketing of these products. 

Researchers from Cardiff University’s Schools of Biosciences, Chemistry and Engineering tested two widely available brands of wipes labelled as ‘biodegradable’ in ten urban rivers and streams in Cardiff, UK 

For five weeks, the team tracked the degradation of the wet wipes in these locations by testing their tensile strength loss, and recording environmental factors such as microbial biomass, water chemistry, temperature, and river-level fluctuations.