Dogs may hold surprising clues to human longevity

 Dogs and humans may share some of the same biological patterns tied to lifespan, according to new research from the Dog Aging Project. The finding could give scientists a useful new way to investigate how aging works in both species.

In a study recently published in The Journals of Gerontology, researchers examined metabolites, small chemicals and molecules created during normal processes in the body. They found that certain combinations of these metabolites were associated with earlier or later death in dogs in ways that closely resembled patterns previously identified in humans.

"The molecules that are risky for dogs or protective against a sooner death are very similar to those in people, showing that we share important features of aging biology, which is really interesting and rewarding," said Dr. Kate Creevy, chief veterinary officer for the Dog Aging Project and a professor in the Texas A&M College of Veterinary Medicine and Biomedical Sciences, where the work of the Dog Aging Project is generously supported by the WoodNext Foundation. "Our findings also highlight the value of pet dogs as a model for studying long-term health and lifespan."

Searching for Biological Signs of Lifespan

Metabolites can provide a snapshot of what is happening inside cells, making them useful for detecting biological patterns that may be connected to health and aging.

For the study, researchers analyzed blood samples from dogs participating in the Dog Aging Project. This community science effort follows dogs throughout their lives, with owners contributing detailed survey information and, in some cases, physical samples. The research team examined the blood for metabolic patterns associated with lifespan, focusing specifically on whether individual dogs died earlier or later.

"Death is an easy outcome to understand," Creevy said. "It is very easy to tell when a person or a dog has died, whereas other features of aging health are a bit more nuanced."

Using mortality as a clear endpoint allows scientists to work backward and investigate which biological processes may have contributed to the outcome. These processes can include metabolism, inflammation and the ways cells react to stress.

"If we understand why something happened, we have a greater chance of identifying ways to change it," Creevy said.

A Metabolic Fingerprint of Aging

Rather than focusing on individual molecules, the researchers analyzed thousands of metabolites together to look for larger patterns associated with risk. Creevy said these broader groups can reveal more about what may be taking place inside cells than any single molecule alone.

"Some of my colleagues refer to it as a fingerprint," Creevy said. "We often look at a pattern or grouping that has a relationship with better or worse outcomes rather than just looking at a single molecule."

These measurable biological indicators, known as biomarkers, can help researchers estimate the likelihood of certain health outcomes by revealing changes occurring inside the body.

"Importantly, those biomarkers do not necessarily cause an outcome; when we find a biomarker associated with sooner or later mortality, we don't know that it's causing it," Creevy said. "But if we understand why that biomarker is present, we may be able to identify what the cause of the relationship is."

Finding these recurring patterns gives scientists possible starting points for investigating the mechanisms behind aging and, eventually, identifying biological targets that might help improve health over time.

Dogs and Humans Share Similar Aging Signals

The researchers then asked whether the metabolic patterns seen in dogs also appeared in people. To find out, they compared their results with five large published studies of human mortality that used similar methods to examine metabolites.

Across those studies, the signals associated with earlier or later death were broadly similar to those found in dogs.

That consistency was one of the most striking results, adding evidence that dogs and humans share important features of the biology that underlies aging.

"Frequently, we know a little more about this in people than we do in dogs," Creevy said. "If we have the same targets, we'll be able to leverage human research to benefit dogs."

The similarities could allow scientists to use knowledge already gained from human research to improve canine health, while also using dogs to study how aging develops across an entire lifespan.

Why Dogs Are Valuable for Aging Research

Pet dogs offer several advantages for researchers studying aging. They share many parts of everyday life with humans, including their surroundings, diets and activity patterns. That overlap gives scientists an opportunity to examine how lifestyle and environment affect long-term health.

"One of the things we like most about learning from dogs as it pertains to aging is their widely varied lifestyles that mirror their owners' lifestyles in a way that's less true for other companion animals," Creevy said.

Cats, for example, often live more independent and relatively consistent lifestyles. Dogs are more likely to follow the routines, environments and activity patterns of the people they live with.

Their shorter lifespans provide another major advantage. Humans, on average, live into their 70s, while dogs typically live only 12-13 years. That difference allows researchers to observe aging and lifespan outcomes in dogs much more quickly than would be possible in human studies.

Inside the Dog Aging Project

The research was made possible by the Dog Aging Project, a nationwide, long-term study that follows pet dogs living with owners across the United States.

Owners who participate provide extensive information about their dogs' lives, while a subset also submit biological samples each year. Together, those contributions allow researchers to track changes in health and aging over time.

"The owners who enroll their dogs make everything possible," Creevy said. "The dedication and commitment of these owners to participate in research and discovery to better the health of dogs is remarkable."

Creevy said the latest findings are an early but important step toward understanding the mechanisms that influence aging. Researchers have now identified metabolic patterns associated with lifespan, giving them specific biological signals to investigate further.

"This is a starting point," she said. "We've identified these metabolites, and now we know where to start looking."

For people who own dogs, Creevy said the practical message is straightforward. Many of the same behaviors that promote healthier aging in people are also likely to benefit dogs.

"Keeping them on a healthy diet, at a healthy body weight, and preserving mobility and cognitive health -- just like we would do for ourselves," Creevy said. "What's good for us is probably good for them."

Source: ScienceDaily

Scientists solve the mystery of a brain “switch” that can trigger weight loss in opposite ways

 Cambridge researchers have uncovered why both activating and blocking the same brain receptor can promote weight loss. The findings may help scientists develop obesity treatments that are more effective and potentially work better in combination.

The mouse study, published in Nature Metabolism, found that the outcome depends on which part of the brain is targeted. Activating the receptor in the brainstem reduced appetite, while blocking the same receptor in the hypothalamus produced a similar weight loss effect through a different mechanism.

More than a billion people around the world are living with obesity, a condition that raises the risk of diseases including type 2 diabetes, cardiovascular disease and cancer. Losing weight can reduce some of these risks, but achieving substantial weight loss through diet and exercise alone can be difficult.

How Modern Weight Loss Drugs Target the Brain

A new generation of weight loss medications has emerged in recent years that act on specific receptors involved in appetite. By influencing these receptors, the drugs can reduce food intake, promote weight loss, and help regulate blood sugar.

Several widely used medications, including Wegovy and Ozempic, activate a protein receptor called the glucagon-like peptide 1 receptor (GLP-1R).

Other obesity treatments act on both GLP-1R and another receptor known as the glucose-dependent insulinotropic polypeptide receptor (GIPR). This second target has presented scientists with an unusual puzzle.

Some medications, including Mounjaro and Zepbound, activate GIPR. Others, such as MariTide, block it. Despite producing opposite effects on the same receptor, both approaches can help promote weight loss.

Researchers at the Institute of Metabolic Science, University of Cambridge, set out to understand why. Their experiments in mice revealed that the two types of GIPR drugs work through different regions of the brain. The researchers also found that these approaches can increase weight loss when paired with certain GLP-1-based weight loss medicines.

Tracking GIPR Activity in Different Brain Regions

To identify the brain regions responsible for these effects, the team used genetically engineered mice in which GIPR had been selectively removed from specific areas.

One group lacked GIPR in the brainstem, the region at the base of the brain just above the spinal cord that is involved in appetite and nausea. Another group lacked the receptor in the hypothalamus, an important brain region involved in regulating hunger and body weight. A third group consisted of normal, unmodified mice that served as controls.

Source: ScienceDaily

Scientists uncover the hidden nerve network fueling breast cancer

 New research from the University of Oklahoma has revealed how an aggressive type of breast cancer can manipulate the immune system to draw nerves into tumors, creating conditions that may help the cancer grow.

Scientists have known for years that many solid tumors contain extensive nerve networks. What has been less clear is how those nerves enter the tumor in the first place. The new study, published in Cell Death & Differentiation, provides an explanation for this process in triple-negative breast cancer, a particularly difficult form of the disease to treat.

Immune Cells Help Draw Nerves Into Tumors

The researchers discovered that tumors attract macrophages, a type of immune cell that normally helps the body fight infections and repair damaged tissue. After entering the tumor, these macrophages release brain-derived neurotrophic factor (BDNF), a protein that encourages nearby nerves to grow toward and into the cancer.

BDNF is most widely known for supporting the growth and survival of nerve cells in the brain. In breast cancer, however, the researchers found that tumors can take advantage of this same biological signal. By prompting nerve growth inside the tumor, the process may contribute to cancer progression and resistance to treatment.

"Macrophages are the critical source for drawing nerves into the tumor. Although macrophages typically play a positive role in the body, they are facilitating a negative function in this scenario of breast cancer," said Maureen Cox, Ph.D., an assistant professor in the Department of Microbiology and Immunology at the OU College of Medicine and a research member of OU Health Stephenson Cancer Center.

Blocking the Signal Slowed Tumor Growth

The discovery could open the door to a different way of treating cancer. Instead of focusing only on destroying cancer cells, future therapies might interrupt the signaling between macrophages and the nerves that appear to support tumor growth.

Cox and her colleagues tested this strategy in mice. They used a drug that blocks BDNF signaling and found that nerves no longer grew into the tumors. Tumor growth was also significantly reduced.

"It looks really promising that we can use this drug, which is already on the market, to target BDNF," Cox said. "We believe that the nerves are immunosuppressive, so if we can stop the nerves from growing in the first place, maybe we can boost the immune response to help fight the cancer."

Evidence From Triple-Negative Breast Cancer Patients

The researchers also examined data from people with triple-negative breast cancer to determine whether the same biological pattern might occur in humans. Tumors containing higher levels of macrophages and BDNF were linked with poorer survival, providing evidence that the mechanism observed in mice could also be relevant to patients.

Source: ScienceDaily

Breast cancer is surging among Asian American women — and scientists don’t know why

 A new UC San Francisco-led study has identified a sharp increase in invasive breast cancer among Asian American women over the past two decades.

Breast cancer rates have climbed across nearly every Asian American ethnic group at a pace that exceeds increases seen in any other U.S. ethnic group. The trend is particularly pronounced among women under 50 and among those diagnosed with advanced disease or certain aggressive forms of breast cancer.

Breast Cancer Rates Are Climbing Quickly

The study, published in JAMA Network Open, found that breast cancer incidence rose by more than 3% annually in nearly every Asian American ethnic group examined. The increases were even greater among Chinese and Vietnamese women.

Native Hawaiian women already have some of the highest breast cancer rates among women in the United States. However, their rates increased by about 1% per year, substantially less than the increases observed among Asian American groups.

Researchers say greater use of breast cancer screening probably does not explain the trend. Screening tends to identify more cancers at earlier stages, yet the fastest increases occurred among cancers that had already spread.

One particularly concerning finding involved triple-negative breast cancer, which is considered the most aggressive subtype. Among Chinese American women, cases of triple-negative breast cancer increased by more than 6% each year between 2017 and 2022.

"These patterns are highly concerning from a disparities standpoint," said senior author Scarlett Lin Gomez, PhD, professor of epidemiology and biostatistics at UCSF and co-leader of the Cancer Control Program at the UCSF Helen Diller Family Comprehensive Cancer Center. "They underscore why it is so important to move beyond treating Asian Americans, Native Hawaiians, and Pacific Islanders as a single population."

A Closer Look at Breast Cancer Risk

To examine these trends, researchers analyzed about 150,000 invasive breast cancer cases diagnosed from 2000 through 2022. The data came from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program.

The analysis included nine specific Asian American, Native Hawaiian, and Pacific Islander (AANHPI) populations across 14 states. Together, those states are home to about two-thirds of the U.S. AANHPI population.

Historically, Asian American women, with the exception of Native Hawaiian women, have had lower breast cancer rates than non-Hispanic white women. That difference is now shrinking quickly. By 2022, breast cancer incidence among Asian American women under 50 had become comparable to the rate among white women of the same age group.

Source: ScienceDaily

Scientists turn probiotic bacteria into tiny drug factories for pancreatic cancer

 Cancer immunotherapy has dramatically changed how doctors treat many forms of cancer, yet pancreatic cancer has remained particularly resistant to these advances. A major obstacle is the environment that develops around pancreatic tumors. These tumors often create a "cold" tumor microenvironment that blocks immune cells from launching an effective attack.

Researchers at the University of Chicago have now developed a new approach that could help overcome this problem. In a study published in Science Advances, the team used BifidoSumIL-2, an engineered strain of Bifidobacterium longum, a probiotic bacterium naturally found in the gut, to carry an immune-stimulating treatment directly into tumors.

In animal models, the therapy slowed the growth of pancreatic tumors by selectively activating T cells that fight cancer. Its effects became even stronger when researchers combined it with chemotherapy, radiotherapy or immunotherapy. The findings suggest that BifidoSumIL-2 could eventually provide a new way to improve how pancreatic tumors respond to treatment.

Using Bacteria to Deliver Cancer Therapy

"A big unmet medical need has been pancreatic cancer, and so that was going to be our mountain to climb," said Ralph Weichselbaum, MD, the Daniel K. Ludwig Distinguished Service Professor and Chair of Radiation and Cellular Oncology at the University of Chicago.

BifidoSumIL-2 was created to release a modified version of interleukin-2 (IL-2) once it reaches a tumor. IL-2 is a potent immune signaling molecule that activates T cells involved in attacking cancer. Conventional IL-2 treatment, however, can produce serious side effects and can also stimulate immune cells that actually weaken the antitumor response.

The researchers sought to avoid these problems by using SumIL-2, a modified form of IL-2 engineered to more precisely activate cancer-fighting T cells while reducing stimulation of regulatory T cells. They then placed SumIL-2 inside Bifidobacterium longum so that the therapeutic molecule could be concentrated within tumors instead of throughout the body.

Developing the treatment required scientists from several disciplines to work together, including specialists in microbiology, synthetic biology, oncology, and immunology.

"This was a highly interdisciplinary effort," said Mark Mimee, PhD, Assistant Professor of Microbiology at the University of Chicago. "We had to bring together people who understand bacteria, people who understand tumors, and people who understand the immune system to make something like this possible."

Why Bifidobacterium Can Target Tumors

Bifidobacterium offered the researchers an unusual advantage as a delivery system. The bacterium grows in anaerobic environments, meaning places with very little oxygen. Low oxygen levels are common inside many solid tumors, including pancreatic tumors, while healthy tissues generally contain more oxygen and are therefore less suitable for the bacteria.

Source: ScienceDaily

AI may know how you’ll respond to a vaccine before you get it

 Vaccines prevent serious illness for many people, but the immune protection they produce can differ substantially from one person to another. New research led by Arizona State University offers clues about what may be behind those differences.

The immune system may show signs of how strongly it will react even before vaccination. Researchers at ASU and collaborating institutions examined blood samples from more than 4,000 people, measuring antibodies that recognized 185 antigens. Those immune targets included common viruses and bacteria, along with targets connected to autoimmune diseases.

Artificial intelligence was then used to search for patterns in blood samples taken before and after COVID-19 vaccination. The analysis uncovered antibody signatures that could help separate people who produced strong vaccine responses from those whose responses were weaker.

The findings could eventually contribute to vaccination strategies tailored more closely to an individual's immune system.

"What our study found is that certain biomarkers, when analyzed with AI, can predict who is likely to respond well to a vaccine, even before they receive it. This suggests that some people may be more immune-ready than others," says Joshua LaBaer, who led the study.

LaBaer is executive director of the Biodesign Institute at ASU and director of the Virginia G. Piper Center for Personalized Diagnostics. The project also involved ASU researchers and collaborators from medical and research institutions around the United States.

The study appears in the current issue of the journal Cell Press Blue.

Blood Antibodies May Reveal Vaccine Readiness

Scientists typically evaluate vaccine response after vaccination by measuring whether the immune system generated antibodies against the intended target. In this study, the researchers approached the problem from the opposite direction. They wanted to know whether immune patterns already present in the blood could reveal how someone would respond before receiving a vaccine.

Many factors can influence vaccine response, including age, sex, genetics, previous illnesses and underlying health conditions. People with conditions that compromise the immune system are often more likely to produce weaker responses. However, vaccine outcomes can still vary widely among people who fall into the same general health categories.

The researchers used one of the first approaches to examine a broad antibody "fingerprint" present before vaccination as a measure of immune readiness. While some other prediction strategies depend on genetic testing, this method analyzes antibody patterns in blood, potentially making it easier to translate into clinical practice.

Source: ScienceDaily

This yeast supplement may boost cancer-fighting immunity

 Researchers at Trinity College Dublin and University College Dublin (UCD) have found that a yeast-based dietary supplement can strengthen immune cells involved in fighting cancer in mice.

In experiments with obese laboratory mice, the researchers found that adding the supplement to the animals' diets changed the way immune cells developed and produced stronger cancer-fighting responses.

Obesity can interfere with immune function, making it more difficult for the body to respond effectively to tumors. The new findings suggest that a yeast-based supplement could potentially help restore some of that lost immune activity.

The research was published in the scientific journal Cell Reports. The study was led by Frederick Sheedy, Associate Professor in Immunology in Trinity's School of Biochemistry and Immunology, and Helen Roche, Professor in Nutrigenomics, UCD School of Public Health, Physiotherapy and Sports Science and Director of the UCD Conway Institute.

Training Immune Cells Through Diet

Dr. Anna Ledwith, postdoctoral researcher in Prof. Roche's group and first author of the research paper, said: "We wanted to investigate whether a common dietary supplement, yeast beta-glucan, could reprogram early-stage immune cells in the bone marrow to produce long-lasting, enhanced anti-tumor immune responses.

"Mice were fed a standard or high-fat diet supplemented with yeast beta-glucan for 4-12 weeks, and then their immune system was challenged by different types of cancer cells: colorectal, skin, and breast cancer. The study also tested whether yeast supplementation could overcome immune dysfunction caused by obesity and whether protective effects persist after weight loss."

The researchers wanted to determine whether consuming yeast beta-glucan could produce a form of lasting immune training by changing early immune cells in the bone marrow. They also examined whether the supplement could counter the immune problems caused by obesity.

Prof. Roche said the findings show for the first time that consuming yeast beta-glucan in the diet is enough to trigger trained immunity by altering bone marrow stem cells. Earlier studies achieved similar effects using injections.

Commenting on the significance of the findings, Prof. Roche added: "This is the first demonstration that dietary delivery of yeast beta-glucan is sufficient to induce trained immunity through reprogramming of bone marrow stem cells. Previous research required injections.

"Crucially, this dietary intervention restores anti-tumor innate immunity in obese mice and reverses long-term immune memory defects that persist even after weight loss, a major unmet clinical challenge."

Source: ScienceDaily

This common vitamin was linked to 13% better cognitive scores

 More than 7 million Americans are currently living with Alzheimer's dementia, and that number is expected to climb to nearly 13 million by 2050. New research from Emory University suggests that higher vitamin D supplement intake may be linked to stronger cognitive performance in adults who face an increased risk of developing dementia.

The study included 54 adults with sleep disturbances and mild cognitive impairments (MCI), both of which can be associated with the early stages of dementia. Participants who reported taking at least 5,000 IU of vitamin D each day performed better on measures of cognitive function than those who did not take vitamin D.

Higher Vitamin D Intake Linked to Better Cognitive Scores

The findings, recently published in Sleep Medicine, showed that people taking 5,000 IU or more of vitamin D daily scored more than 13% higher on the Montreal Cognitive Assessment (MoCA) compared with participants who took none, even after researchers adjusted for other factors.

MoCA is a widely used screening test designed to assess memory, thinking skills, and the risk of developing dementia. In contrast to the results seen with the higher intake group, lower daily doses of vitamin D were not associated with improved cognitive scores.

The researchers also highlighted the potential importance of when an intervention takes place. MCI is an intermediate stage between normal cognitive aging and dementia.

"In older adults experiencing both sleep disturbance and mild cognitive impairment, this may represent a critical window for intervention, when cognitive changes are emerging, but opportunities to support brain health may remain," says Victoria Pak, senior author of the study.

"Identifying accessible and modifiable factors, such as vitamin D supplement intake, during the earlier stages of cognitive decline may become increasingly important, particularly as rates of Alzheimer's disease continue to rise," adds Pak, associate professor at Emory University's Nell Hodgson Woodruff School of Nursing.

Vitamin D2 and D3 Showed Similar Results

The researchers also examined whether the form of vitamin D made a difference. Cognitive performance was similar among people taking vitamin D2, which is typically obtained from plants or fungi, and vitamin D3, which the body produces after sun exposure and which can also come from animal-based foods.

Vitamin D is an essential nutrient involved in muscle and nerve function, and it also plays a role in sleep quality and sleep-wake cycles. Sleep problems are common among people with Alzheimer's disease. 50% of those with moderate to severe Alzheimer's disease report sleep disturbances, pointing to a two-way relationship between poor sleep and cognitive decline.

Source: ScienceDaily

Scientists detect a sharp acceleration in global warming

 Global warming has sped up since around 2015, according to a new analysis from the Potsdam Institute for Climate Impact Research (PIK). After removing the effects of natural temperature swings, researchers found the first statistically significant evidence that the planet's long-term warming rate is accelerating.

Over the past decade, global temperatures have risen at an estimated pace of about 0.35°C per decade, depending on the dataset used. By comparison, the average warming rate from 1970 to 2015 was just under 0.2°C per decade. The recent pace is higher than that of any previous decade since instrumental temperature records began in 1880.

Scientists Isolate the Long-Term Warming Signal

"We can now demonstrate a strong and statistically significant acceleration of global warming since around 2015," says Grant Foster, a US statistics expert and co-author of the study, which was published today in the scientific journal Geophysical Research Letters.

"We filter out known natural influences in the observational data, so that the 'noise' is reduced, making the underlying long-term warming signal more clearly visible," Foster added.

In climate data, "noise" refers to short-erm temperature changes that can temporarily hide or exaggerate the underlying trend. El Niño, for example, can push global temperatures higher for a limited period by releasing heat from the tropical Pacific Ocean into the atmosphere. Volcanic eruptions can have the opposite effect by sending particles into the atmosphere that reflect sunlight, while changes in the Sun's activity can also produce smaller temperature variations.

To separate these temporary influences from the broader warming trend, the researchers analyzed measurements from five widely used global temperature data sets (NASA, NOAA, HadCRUT, Berkeley Earth, ERA5).

"The adjusted data show an acceleration of global warming since 2015 with a statistical certainty of over 98 percent, consistent across all data sets examined and independent of the analysis method chosen," explains Stefan Rahmstorf, PIK researcher and lead author of the study.

Warming Acceleration Appears Across Five Datasets

A statistical certainty of more than 98 percent means the researchers found strong evidence that the change in the warming rate is real rather than the result of random variation in the data. The same overall pattern appeared in all five temperature records, even though the datasets are produced by different scientific organizations and use somewhat different methods.

After the researchers adjusted for El Niño and the solar maximum, the extreme warmth of 2023 and 2024 was reduced slightly in the analysis. Even so, both years remained the two warmest since instrumental records began.

Across all of the datasets, the acceleration started to become visible in 2013 or 2014. The researchers describe the broader shift as beginning around 2015, when the evidence became clearer.

Two Statistical Methods Point to the Same Shift

To determine whether the warming rate had changed since the 1970s, the team used two statistical approaches. The first was a quadratic trend analysis, which tests whether the temperature curve is bending upward over time rather than rising at a constant rate.

The second was a piecewise linear model. This method divides the temperature record into separate periods and objectively identifies when the rate of warming appears to change. Both approaches supported the conclusion that global warming has accelerated.

Study Does Not Identify the Cause

The research was designed to detect and measure the statistical acceleration, not to determine exactly why it has occurred.

However, the authors noted that climate models can produce periods in which warming speeds up. In other words, an increasing rate of warming is consistent with the range of behavior represented in current climate modeling.

Climate models are computer simulations that use the laws of physics to estimate how the atmosphere, oceans, ice, and land respond to greenhouse gases and other influences. They do not predict every short-term fluctuation perfectly, but they help scientists evaluate long-term climate patterns and possible future changes.

1.5°C Threshold Could Be Exceeded Before 2030

"If the warming rate of the past 10 years continues, it would lead to a long-term exceedance of the 1.5°C limit of the Paris Agreement before 2030," says Stefan Rahmstorf. "How quickly the Earth continues to warm ultimately depends on how rapidly we reduce global CO2 emissions from fossil fuels to zero."

The 1.5°C limit refers to the goal of restricting long-term global warming to 1.5°C above preindustrial temperatures. A single year above that level does not by itself mean the Paris Agreement threshold has been permanently crossed. Scientists generally focus on sustained warming over a longer period.

Source: ScienceDaily

Ancient Arctic carbon is pouring into the sea, but the seabed captures most of it

 The Arctic's frozen ground contains enormous stores of organic carbon. As permafrost thaws and coastlines erode, some of that carbon is carried into the ocean. There, microorganisms can break it down and release greenhouse gases that contribute to climate change.

Until now, scientists have had limited information about how much of this carbon returns to the atmosphere and how much remains trapped in the ocean. Researchers from the Alfred Wegener Institute and MARUM - Centre for Marine Environmental Sciences at the University of Bremen have now examined this process along the permafrost coast of Qikiqtaruk (Herschel Island) in Canada.

By studying sediment cores, the team found that large amounts of carbon from land are preserved in the seafloor. They also discovered that marine microorganisms behave like selective eaters, favoring fresh carbon from the ocean over older carbon released from permafrost. The findings were published in Nature Geoscience.

Vast Carbon Stores Are Beginning to Thaw

Permafrost ecosystems on Arctic land contain about 1,300 gigatonnes of organic carbon, much of it from plant remains. Another 400 gigatonnes are stored in ocean sediments and river deltas.

As the planet warms, the Arctic is heating faster than any other region. This rapid temperature rise is causing frozen ground to thaw and coastlines to break apart. Carbon that was previously locked in the soil can then reach the Arctic Ocean through rivers and coastal erosion.

"Consequently, up to 0.02 gigatonnes are entering the sea each year, and according to forecasts, this outflow could rise by 70 to 150 percent by the year 2100," says Dr. Manuel Ruben, lead author of the study from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). "However, how much of this is released back into the atmosphere as a greenhouse gas and how much is stored in the seabed has, until now, been largely unknown."

Resolving that uncertainty is important because scientists need to know where the carbon ultimately ends up to estimate how thawing permafrost could affect the climate.

Sediment Cores Reveal Where the Carbon Goes

To investigate, the researchers collected sediment cores from several locations off the coast of Herschel Island. These cores contain layers of material deposited over roughly 50 years.

The results showed that only a relatively small share of the carbon swept into the ocean becomes part of the active carbon cycle.

"Although the sea here carries away huge quantities of organic carbon from the coast, surprisingly little of it ends up in the ocean's active carbon cycle," says Manuel Ruben. "Microorganisms convert around ten percent of the organic carbon from the sediments into gases, which rise into the water and can then enter our atmosphere."

Most of the remaining carbon stays buried in the seabed.

Chemical Clues Track Microbial Activity

The scientists analyzed the composition of the sediment cores and measured how quickly material from the permafrost accumulated on the ocean floor.

They also studied dissolved inorganic carbon found in tiny spaces between sediment particles, known as pore water. These measurements reveal how much CO2 microorganisms have released after consuming organic material.

The isotopic makeup of the pore water helped the team determine where that material came from.

"Carbon isotopes represent our atomic indicators that can identify the food source of the microorganisms," says Prof. Gesine Mollenhauer, a geochemist at the AWI and co-spokesperson for the 'The Ocean Floor - Earth's Unexplored Interface' cluster of Excellence. "The 13C isotope, for example, tells us whether they have consumed carbon from land or from the sea. By way of the 14C isotope, we were able to determine whether the single-celled organisms preferred old organic carbon from permafrost or fresh organic carbon from algae remains."

"Gourmet" Bacteria Prefer Fresh Carbon

The results suggest that the organisms living in the sediment are not equally interested in every type of carbon.

"The sediment is home to 'gourmet' bacteria that apparently prefer fresh carbon stemming from, for example, more recent algal remains over the 'old' carbon from permafrost deposits," explains Gesine Mollenhauer.

Because the microbes favor fresh marine material, older carbon from thawing permafrost may contribute less to atmospheric greenhouse gas levels than scientists once feared.

However, the researchers caution that the full picture is not yet clear.

"However, we do need further research here. This is because some of the organic carbon from the permafrost may already have been broken down before it reaches the seabed."

Coastal Carbon Could Reshape Arctic Ecosystems

The movement of carbon from land into the ocean may affect more than greenhouse gas emissions. It can also change the chemistry and biology of coastal waters that support food resources for local communities.

Sediment released by coastal erosion can reduce the amount of sunlight entering the water. Freshly eroded fragments make the coastal ocean cloudy, while dissolved organic carbon can darken the water.

That loss of light can affect single-celled organisms such as algae, which need sunlight to produce biomass and oxygen. This primary production supports a wider food web that includes fish, crustaceans and seals.

The researchers plan to explore these connections further during the international 'Arctic Pulse' campaign scheduled for 2027. Scientists will carry out coordinated observations from the Polarstern research icebreaker, aboard AWI research aircraft and at sites on land. Their goal is to understand how rapid environmental change is transforming Arctic ecosystems.

Improving Arctic Climate Models

"Our study shows, more precisely than ever before, how much carbon is safely stored in the seabed - and just how much of the decomposed material actually originates from the old permafrost," says Manuel Ruben. "This provides an important foundation for climate models that can predict the consequences of permafrost thawing for the global climate."

Source: ScienceDaily

The AMOC stayed strong even as a major ocean “lifeline” nearly shut down

 Scientists have long believed that warm, salty water flowing from the Indian Ocean around the southern tip of Africa and into the Atlantic helps support one of the planet's most important ocean circulation systems. This flow, known as Agulhas Leakage, has been considered a major contributor to the Atlantic Meridional Overturning Circulation (AMOC), which forms part of the global ocean conveyor system.

New findings from an international research team based in the Netherlands, USA, China and UK suggest that this relationship is more complicated than previously assumed. Their results indicate that changes in Agulhas Leakage do not always produce the expected response in deep water formation. The study offers a clearer picture of how the AMOC works and how its behavior may vary under different climate conditions.

Testing a Textbook Explanation of the AMOC

The Atlantic Meridional Overturning Circulation (AMOC) transports warm surface water toward the north while carrying colder, denser water back toward the south at greater depths. Through this exchange, it influences temperatures across the North Atlantic and much of Europe, making it a central part of the global climate system.

For decades, researchers have proposed that Agulhas Leakage helps maintain or strengthen the AMOC. This leakage carries warm, salty Indian Ocean water around South Africa and into the Atlantic. Its strength is influenced by shifts in the position of the subtropical front. According to the traditional explanation, the added salt encourages the formation of North Atlantic Deep Water, which helps sustain Atlantic overturning.

"This was basically the first textbook concept, that I learnt when I was a bachelor student. It was surprising to find geological evidence showing that it isn't universally true. The AMOC can remain strong even when Agulhas Leakage weakens," explains lead author Dr. Suning Hou from Utrecht University.

Hou and his colleagues examined conditions during the late Pliocene (3.6-2.6 million years ago). This period included a short but significant glacial event followed by the mid-Piacenzian Warm Period, when global conditions were warmer than they are today. The transition provided researchers with a useful opportunity to study how ocean circulation near South Africa and within the Atlantic responded as the climate shifted from cooler to warmer conditions.

Ancient Sediments Reveal Shifting Ocean Boundaries

The team studied a marine sediment core collected from International Ocean Discovery Program Site U1475 on the Agulhas Plateau, about 500 kilometers south of South Africa.

Within the core, researchers examined fossilized microplankton known as dinocysts, along with organic lipid biomarkers. These materials allowed them to estimate past ocean temperatures and track movements of the Southern Ocean subtropical front toward the north or south.

Hou: "If you find a change in the dinocyst assemblage in the sediment, this means that the front shifted. For instance, if you find more of the warmer species and less of the colder ones, the front has moved south. A more southerly front generally opens a wider pathway for Indian Ocean water to leak into the Atlantic, and vice versa."

Using these indicators, the researchers produced a detailed reconstruction of possible changes in Agulhas Leakage throughout the late Pliocene.

To determine how the Atlantic responded, they also developed temperature records from Ocean Drilling Program Site 625 in the northern Gulf of Mexico. They combined those findings with previously published evidence from the equatorial Atlantic, the North Atlantic and the Caribbean Sea.

The team then compared the geological records with numerical climate model simulations covering the late Pliocene glacial event and the warmer period that followed. Together, the evidence from several ocean basins connected movements of the Southern Ocean front with changes in Atlantic temperature layers and overturning circulation.

Agulhas Leakage Declined While Overturning Intensified

The reconstruction from waters south of Africa showed that the subtropical front began moving northward around 3.4 million years ago and continued doing so during the glacial event.

At the same time, temperatures in the Agulhas region fell by about 3 degrees Celsius. Site U1475 also developed subpolar conditions. These changes indicate that Agulhas Leakage weakened dramatically and may have come close to stopping.

According to the conventional theory, a reduction in the transport of salty water should have weakened the AMOC. Instead, both the geological evidence and the computer simulations revealed the opposite pattern in important parts of the circulation system.

During the glacial interval, the North Atlantic Current did not extend as far into the high northern latitudes. Even so, the formation of North Atlantic Deep Water became stronger, as did overturning at lower latitudes. This intensified circulation caused the thermocline, the boundary between warmer surface water and colder deep water, to become shallower across the Atlantic.

Source: ScienceDaily

Marine heatwaves are harming human health in surprising ways

 Marine heatwaves are increasingly being recognized as more than an environmental problem. New research warns that prolonged periods of unusually warm ocean temperatures can also threaten human physical and mental health.

Researchers from Adelaide University and the University of Hong Kong say marine heatwaves should be treated as an important public health concern. They argue that the effects on people have received relatively little attention, even as evidence continues to show how widely these events can affect communities.

The consequences can be severe. The rapid strengthening of Hurricane Otis in 2023 and the destruction it caused in Mexico (an estimated damage bill of more than US$15 billion) have been linked to marine heatwaves. Typhoon Doksuri in 2023, which had impacts across Asia (which affected more than two million people across Asia), has also been associated with unusually warm ocean conditions.

In South Australia, a devastating algal bloom linked to marine heat conditions has also been associated with numerous health problems in coastal communities.

How Marine Heatwaves Can Affect Human Health

A new paper published in Nature Sustainability describes how sustained periods of abnormally high ocean temperatures can set off a chain of consequences for people. These include more severe weather, reduced seafood availability, threats to food safety, disrupted livelihoods and greater mental health pressures in coastal areas.

Lead author Dr. Laura Falkenberg, from Adelaide University's School of Physics, Chemistry and Earth Sciences, said researchers have long recognized the ecological damage caused by marine heatwaves, but their effects on humans have attracted much less attention.

"Marine heatwaves are no longer just recognized as an environmental issue; they are increasingly also perceived as a human health issue," Dr. Falkenberg said.

"Our paper highlights that these events can influence people's health in many different ways, both directly and indirectly. They can intensify storms and atmospheric heatwaves, affect the availability and safety of seafood, disrupt livelihoods and contribute to anxiety, grief and other mental health impacts in communities that depend on healthy oceans."

Marine heatwaves are becoming more frequent, lasting longer and reaching greater intensity as the climate warms. Scientists have already connected them with widespread coral bleaching, large-scale deaths of marine organisms, harmful algal blooms and major disruptions to fisheries and aquaculture.

According to the researchers, those environmental disruptions can have serious consequences for people as well.

Stronger Storms, Unsafe Seafood and Food Security Risks

Extremely warm ocean water can help strengthen weather systems, raising the danger of injuries, deaths and displacement caused by storms and flooding.

Marine heatwaves can also make harmful algal blooms more likely. These blooms can contaminate seafood and create significant health hazards for people who consume or come into contact with affected marine environments.

The effects can continue long after an individual heatwave ends. Falling fish populations and reduced seafood production could undermine food security for billions of people around the world who depend on the ocean as an important source of nutrition.

The Mental Health Toll of a Changing Ocean

The researchers also draw attention to the psychological effects of marine ecosystem loss. People whose livelihoods, traditions and cultural identities are closely tied to the ocean can experience significant emotional stress as familiar environments deteriorate.

In 2025, the toxic algal bloom in South Australia was associated with high levels of 'eco-anxiety,' as well as grief, frustration and depression. The bloom was also linked to physical health problems including respiratory irritation and asthma.

"Many people rely on healthy oceans not only for food and income, but also for recreation, cultural identity and their overall sense of well-being," Dr. Falkenberg said.

"When marine ecosystems suffer, the impacts ripple through communities. We are seeing increasing evidence that these changes can contribute to eco-anxiety, grief and other mental health challenges, particularly for people who feel deeply connected to the marine environment."

Researchers Call for Public Health Planning

The authors say governments and public health agencies should prepare for marine heatwaves in ways similar to how they prepare for heatwaves on land.

That could include using marine heatwave forecasts in public health planning, accounting for human health consequences when making coastal and marine management decisions, and strengthening cooperation among ocean scientists, health agencies and resource managers.

Dr. Falkenberg said preparing before emergencies happen could make communities more resilient as marine heatwaves become increasingly severe.

"Recognizing these health impacts is the first step towards better protecting communities," she said.

"If we only respond after disasters occur, we will continue to experience greater impacts than if we had acted proactively. By understanding the links between ocean health and human health, we can develop better policies that protect both people and the marine ecosystems they depend on."

Source: ScienceDaily

Scientists turn Starlink into a giant scanner for Earth’s upper atmosphere

 The region surrounding Earth is getting more crowded as thousands of satellites and pieces of space debris move through low Earth orbit. Farther above, at altitudes of several hundred kilometers, traces of Earth's upper atmosphere can still exert enough drag to slow satellites. Accurately measuring atmospheric density at these heights is therefore important for forecasting satellite motion and reducing the risk of collisions.

More than 99 percent of the upper atmosphere consists of electrically neutral gas known as the thermosphere. The term thermospheric density refers to the density of this neutral atmosphere between about 100 and 1000 kilometers above Earth's surface. By comparison, the ionized gas of the ionosphere accounts for less than 1 percent of the atmosphere. Because ionized gas affects the way radio waves travel, the ionosphere is relatively straightforward to observe. Measuring conditions in the thermosphere is much more difficult.

A New Way to Observe the Thermosphere

Better measurements of thermospheric density could advance research into the upper atmosphere while also providing valuable information for space engineering. Motivated by both needs, researchers at Kyoto University developed a new technique for visualizing this difficult-to-observe region.

"This is a multidisciplinary study between space science and space engineering," says corresponding author Mamoru Yamamoto. "Reading papers from both research fields, we realized that deeper dialogue between researchers from both fields is necessary."

The researchers used publicly available orbital information from Starlink satellites and applied tomography, a technique commonly associated with medical imaging, to Earth's upper atmosphere. By examining atmospheric drag through the gradual decay of satellite orbits, the team estimated thermospheric density around approximately 1,200 satellites flying at an altitude of 482 kilometers.

Building a Two-Dimensional Atmospheric Map

Using those measurements, the researchers produced a two-dimensional latitude-longitude snapshot of thermospheric density at an altitude of roughly 500 kilometers. According to the team, this represents the first tomographic analysis of its kind.

The resulting density patterns also showed strong consistency with observations from the European Space Agency's SWARM satellites, which measure changes in atmospheric density along their orbital paths.

The work expands on an earlier study by the same team. In that research, scientists estimated how thermospheric density changed over time and altitude using general orbital information called Two-Line Element, or TLE, data from Starlink satellites. The new analysis adds another dimension by examining how density varies horizontally across latitude and longitude, revealing more of the thermosphere's geographic structure.

Making Crowded Orbits Safer

The findings could have practical benefits as the number of objects orbiting Earth continues to grow. More accurate information about atmospheric density can improve predictions of satellite motion, helping reduce the chance of collisions between satellites and between satellites and space debris.

The technique could also eventually support near-real-time measurements of atmospheric density around satellites. Such monitoring could improve space weather forecasting and contribute to safer, more dependable satellite operations in the future.

Source: ScienceDaily

The Atlantic Ocean can handle more warming than expected — with one big catch

 For years, climate scientists have warned that the Atlantic Meridional Overturning Circulation (AMOC) could eventually shut down if global temperatures rise too far. New findings from researchers at Utrecht University suggest that temperature alone does not determine the fate of this major ocean circulation system. The speed at which the planet warms also appears to play a critical role in whether the AMOC remains stable. The study was published in the scientific journal Nature Climate Change.

The Atlantic Meridional Overturning Circulation, or AMOC, is a vast network of ocean currents that carries warm water northward from the tropics. By moving heat around the planet, it strongly influences the global climate and helps maintain the relatively mild conditions found in Western Europe.

Scientists have long viewed this Atlantic 'heat engine' as a system that could cross a tipping point. If that happened, the AMOC could transition from its current strong circulation to a much weaker state within decades. Possible triggers include growing amounts of meltwater entering the ocean from polar regions as well as global warming itself.

Rethinking the AMOC Temperature Threshold

Researchers previously estimated that the AMOC could reach a tipping point and collapse at around +4°C of global warming. Scientists at the Institute for Marine and Atmospheric research Utrecht now say that this temperature threshold does not tell the whole story.

"Our results show there is not necessarily a fixed temperature beyond which the AMOC inevitably collapses," says lead author René van Westen. "The stability of the circulation depends on how fast the climate is changing."

The findings indicate that two worlds reaching the same eventual temperature could experience very different outcomes for the AMOC depending on how quickly the warming occurred.

Slow Warming Versus Fast Warming

To test the importance of warming speed, Van Westen and his colleagues ran two versions of a climate model. In both simulations, atmospheric CO2 increased gradually, but the rate of that increase differed substantially.

In one simulation, CO2 concentrations increased slowly (0.5 ppm per year). In the second, they climbed much more rapidly (2.5 ppm per year), which is comparable to today's rate.

The contrast produced dramatically different results. When warming occurred slowly, the AMOC remained stable well beyond +4°C and did not collapse even after warming reached +5°C. Under the faster warming scenario, however, the AMOC collapsed at around +2°C.

"We deliberately looked at a scenario that is much slower than what we're experiencing today," explains co-author Reyk Börner. "That allowed us to isolate the effect of the warming rate alone, independent of how warm it eventually gets."

Why the Ocean Needs Time to Adapt

The researchers say the difference comes down to the ocean's ability to respond to changing conditions.

"Under slow warming, the entire ocean, from the surface down to its deepest layers, has time to gradually reorganize and adapt to the changing conditions," says co-author Henk Dijkstra, professor of Dynamical Oceanography. "Under faster warming, the ocean simply can't keep up."

Slow climate change gives the ocean more time to adjust throughout its full depth. When temperatures rise more rapidly, those adjustments cannot happen quickly enough, leaving the circulation more vulnerable to instability.

A Critical Rate of Global Warming

According to the researchers, the critical warming rate is around 0.3°C per decade. The world is already approaching that pace.

Van Westen compares the situation to driving a car: "If you're driving toward a wall, it makes sense to steer around it. To do that, you need to brake, otherwise you fly off the road. When it comes to global warming, the world is still pressing extra hard on the accelerator right now."

The analogy highlights an important distinction. Avoiding dangerous climate changes may depend not only on limiting how warm the planet eventually becomes, but also on slowing how quickly it gets there.

Previous Research on AMOC Stability

The same research group has investigated AMOC stability from several different perspectives in recent years.

In 2024, the researchers found that increasing amounts of meltwater entering the North Atlantic make the AMOC less stable. Scientists had suspected this mechanism for years, but the research was the first to demonstrate it using a modern, complex climate model.

Those results showed that a critical meltwater threshold exists, beyond which the AMOC becomes unstable. However, the threshold was unrealistically high. This suggests that the present-day AMOC is unlikely to become unstable through this contribution alone. That study did not include the effects of global warming or the pace at which warming occurs.

A later study explored several global warming scenarios. It concluded that the AMOC could reach a tipping point around 2060 under both an intermediate- and high-emission scenario. In those simulations, the tipping point occurred at approximately 2.5°C of global warming.

The latest research helps explain why studies can produce different estimates for when the AMOC might reach a tipping point, as well as why temperature thresholds vary across climate models and emissions scenarios.

The AMOC does appear to have a critical threshold for meltwater, but the researchers find no universal temperature threshold for its collapse. Instead, its stability depends partly on how quickly the planet warms. Faster warming leaves the AMOC more vulnerable, while slower warming gives the ocean more time to adjust and allows the circulation to remain stable under substantially higher levels of global warming.

What the Findings Mean for Climate Policy

The findings suggest that slowing the pace of warming could reduce the near-term risk of an AMOC collapse by giving the Atlantic Ocean more time to adapt.

That could have important implications for climate policy. Much of current climate policy, including the Paris Agreement, focuses on limiting the eventual peak in global temperature.

Some strategies involve so-called overshoot pathways. Under these approaches, global temperatures would temporarily rise beyond a target limit, with the expectation that future technologies could later reduce temperatures again.

The new findings suggest that the path taken toward a given temperature may matter alongside the temperature itself. The faster global warming occurs, the less time the Atlantic Ocean has to adjust, potentially increasing the vulnerability of one of the planet's most important circulation systems.

Source: ScienceDaily