Monday, January 15, 2024

Cannabis has no clear effect on treatment of opioid addiction, US study finds

Finding has significant implications for treatment programmes – with a growing number of states authorizing cannabis use to help opioid addiction

Peer-Reviewed Publication

TAYLOR & FRANCIS GROUP

Cannabis is not an effective treatment for opioid addiction, a new peer-reviewed study of thousands of people being treated for opioid use disorder suggests.

Experts, publishing their results today in The American Journal of Drug and Alcohol Abuse, have found that cannabis is having no significant effect on peoples’ use of opioids, taken outside of medical guidance.

The findings have substantial implications for U.S treatment programmes, some of which still require patients to abstain from cannabis before they qualify for potentially life-saving treatment. This is based on the belief they are more likely to use opioids non-medically if they are using cannabis.

The opposing, and increasingly popular, viewpoint, that cannabis can help wean people with opioid use disorder off opioids, is also called into question in this new study.

Opioids are effective painkillers, but they can also be addictive, and the U.S. remains in the grip of an opioid use disorder crisis.

Around 120 people die a day from drug overdoses involving opioids (prescription, such as oxycodone, and non-prescription, such as heroin) and opioid use disorder and related deaths cost the US economy more than $1 trillion a year.

As cannabis gains popularity among individuals with opioid use disorder in the U.S., its medicinal use is now legally recognized in thirty-seven states and Washington D.C. While pain remains the most common reason for medical cannabis authorization (i.e., “medical cannabis registration card”), an increasing number of states are adding “alternatives to opioids” or “opioid-treatable disorders” to their lists of approved conditions. In certain states, this includes treatment for opioid use disorder.

The study’s authors say this partly because the legalisation of the recreational use of cannabis in many states means the drug is being perceived as being less harmful than in the past. Some cannabis dispensaries have promoted medicinal cannabis as a treatment for opioid use disorder.

It isn’t clear, however, whether cannabis helps or hinders the treatment of opioid use disorder. Some studies have found it helps alleviate pain and opioid withdrawal, but others suggest it makes a return to opioids more likely.

“Clarifying how cannabis and opioids interact is crucial if we are to equip healthcare professionals to provide evidence-based addiction treatment, prevent overdose deaths and save lives,” says researcher Gabriel Costa, of University of Ribeirão Preto in Brazil.

Costa, under the mentorship of Dr. Joao P. De Aquino, of Yale University, and colleagues, carried out a systematic review and meta-analysis of existing research on the influence of cannabis on non-medical opioid use.

The meta-analysis combined the results of ten longitudinal studies involving 8,367 individuals who were receiving medication (buprenorphine, methadone or naltrexone) to treat their opioid use disorder.

As part of this, over the course of an average of 10 months, individuals were monitored for their non-medical opioid use – including the use of opioids not prescribed to them, taking more opioids than prescribed, or using opioids without a prescription.

The study compared the frequency of this use between individuals who used cannabis, typically obtained from non-regulated sources, and those who did not use cannabis.

Results showed there to be no link between cannabis use and rates of non-medical opioid use.

“Overall, we found no significant association between cannabis and non-medical opioid use among patients receiving pharmacotherapies for opioid use disorder,” states Costa.

“These findings neither confirm concerns about cannabis increasing non-medical opioid use in individuals being treated for opioid use disorder, nor do they endorse its efficacy in reducing non-medical opioid use.”

The implications for opioid use disorder treatment programmes are significant, adds Dr. De Aquino, who is a specialist in the treatment of persons with substance use disorders and co-occurring medical and psychiatric disorders.

He explains: “Our finding questions the ineffective practice of enforcing cannabis abstinence as a condition to offer life-saving medications for opioid use disorder.

“Our data suggests healthcare systems should instead adopt individualised treatment approaches which take into account each patient’s circumstances.

“This would include assessing cannabis use disorder, a problematic pattern cannabis use that affects a person’s wellbeing and ability to function, addressing pain management needs and treating co-occurring psychiatric conditions, such as depression and anxiety.”

Dr. De Aquino adds that there have been very few experimental studies into cannabis and its constituent cannabinoids’ ability to alleviate symptoms of opioid use disorder, and randomised placebo-controlled trials are needed to thoroughly assess its safety and effectiveness.

He says: “As high-potency synthetic opioids such fentanyl become increasingly available, it is of utmost importance that individuals with opioid use disorder have access to FDA-approved treatments.

“Methadone, buprenorphine, and extended-release intramuscular naltrexone – are known to be life-saving and are the cornerstone of opioid use disorder management.”

Limitations include a lack of consistency in how the studies in systematic review and meta-analysis were conducted. This includes differences in how cannabis and opioid use were measured and variations in baseline opioid use status.

In addition, although the results are applicable to general cannabis use, they may not apply to individuals with cannabis use disorder.

JOURNAL

The American Journal of Drug and Alcohol Abuse

DOI

10.1080/00952990.2023.2287406

METHOD OF RESEARCH

Systematic review

SUBJECT OF RESEARCH

People

ARTICLE TITLE

The Impact of Cannabis on Non-Medical Opioid Use Among Individuals Receiving Pharmacotherapies for Opioid Use Disorder: A Systematic Review and Meta-Analysis of Longitudinal Studies

ARTICLE PUBLICATION DATE

16-Jan-2024

COVID-19 vaccine reduces long COVID in children

Vaccination associated with moderate protection in large, diverse cohort

Peer-Reviewed Publication

CHILDREN'S HOSPITAL OF PHILADELPHIA

Philadelphia, January 16, 2024 – Vaccination against SARS-CoV-2, the virus that causes COVID-19, reduces the risk of serious acute illness in children and adolescents. However, its role in protecting against persistent health problems in the months after COVID-19, or “long COVID,” was less clear. Now, researchers from 17 health systems in the U.S., in work led by investigators at the Children’s Hospital of Philadelphia (CHOP), have found that vaccination provides moderate protection against long COVID. Vaccination also has a stronger effect in adolescents, who have a higher risk of developing long COVID than young children.

The findings of the large retrospective study, based on electronic health records analyzed as part of the National Institutes of Health’s Researching COVID to Enhance Recovery (RECOVER) initiative, were published today in the journal Pediatrics.

While overall severity of COVID-19 has been lower in children than adults, the burden of long COVID has been difficult to accurately describe since the symptoms can vary widely and the exact ways the virus causes them are unknown. Some symptoms include brain fog, dyspnea, gastrointestinal dysfunction, generalized pain and fatigue, while others are more acute, like inflammatory reaction or heart problems.

“To date, no studies have assessed clinical data for large, diverse groups of children to address this important question,” said lead study author Hanieh Razzaghi, PhD, MPH, Director of Analytics in the PEDSnet and RECOVER/PCORnet EHR Coordinating Centers in the Applied Clinical Research Center at Children’s Hospital of Philadelphia. “Using clinical data from across health care networks allowed us to have a large enough sample of patients to identify rare effects of the virus and its impact on children.”

The researchers analyzed results from a large-scale collaboration of health systems from PCORnet® as part of the National Institutes of Health’s Researching COVID to Enhance Recovery (RECOVER) initiative, which was created to learn about the long-term effects of COVID-19. Data from 17 health systems were used to assess vaccine effectiveness against long COVID in two groups of patients between 5 and 11 years old and 12 and 17 years old, respectively, as well as the time period in which patients were impacted. The vaccination rate was 56% in the cohort of 1,037,936 children.

The incidence of probable long COVID was 4.5% among patients with COVID-19, though only 0.7% of patients were clinically diagnosed with long COVID. The study estimated effectiveness of the vaccine within 12 months of administration as 35.4% against probable long COVID and 41.7% against diagnosed long COVID. The estimate was higher in adolescents compared with younger children (50.3% vs. 23.8%), and higher at six months (61.4%) but decreased to 10.6% at 18 months. Children who were vaccinated after recovering from COVID-19 also appeared to benefit, with vaccine effectiveness of 46% against probable long COVID after a subsequent episode of COVID-19.

“This study provides us with important data showing the protective effects of the vaccine against long-haul COVID and suggests that this protection is mostly from preventing visible infections. We hope this means that as vaccines are improved to be more effective against current strains of SARS-CoV-2, their protection against long COVID will get better, too,” said senior study author Charles Bailey, MD, PhD, Associate Professor of Pediatrics and co-principal investigator for the PEDSnet and RECOVER/PCORnet EHR Coordinating Centers in the Applied Clinical Research Center at CHOP. “These retrospective data provide guidance for additional research into the ways long COVID develops, and how we can better protect children and adolescents.”

This study was supported by the National Institutes of Health (NIH) Agreement OT2HL161847-01 as part of the Researching COVID to Enhance Recovery (RECOVER) program of research.

Razzaghi et al, “Vaccine Effectiveness Against Long COVID in Children.” Pediatrics. Online January 16, 2024. DOI: 10.1542/peds.2023-064446.

About Children’s Hospital of Philadelphia:

A non-profit, charitable organization, Children’s Hospital of Philadelphia was founded in 1855 as the nation’s first pediatric hospital. Through its long-standing commitment to providing exceptional patient care, training new generations of pediatric healthcare professionals, and pioneering major research initiatives, the hospital has fostered many discoveries that have benefited children worldwide. Its pediatric research program is among the largest in the country. The institution has a well-established history of providing advanced pediatric care close to home through its CHOP Care Network, which includes more than 50 primary care practices, specialty care and surgical centers, urgent care centers, and community hospital alliances throughout Pennsylvania and New Jersey, as well as the Middleman Family Pavilion and its dedicated pediatric emergency department in King of Prussia. In addition, its unique family-centered care and public service programs have brought Children’s Hospital of Philadelphia recognition as a leading advocate for children and adolescents. For more information, visit https://www.chop.edu.

JOURNAL

PEDIATRICS

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Vaccine Effectiveness Against Long COVID in Children

ARTICLE PUBLICATION DATE

16-Jan-2024

First all-UK study of 67 million people reveals consequences of missed COVID-19 vaccines

Peer-Reviewed Publication

HEALTH DATA RESEARCH UK

The first research study of the entire UK population highlights gaps in COVID-19 vaccine coverage. Between a third and a half of the populations of the four UK nations had not had the recommended number of COVID vaccinations and boosters by summer 2022.

Findings suggest that more than 7,000 hospitalisations and deaths might have been averted in summer 2022 if the UK had had better vaccine coverage, according to the paper, published today in The Lancet.

With COVID-19 cases on the rise and a new variant strain recently identified, this research provides a timely insight into vaccine uptake and hesitancy and could inform policy-makers.

The findings – led by Health Data Research UK (HDR UK) and the University of Edinburgh – relied on secure access to anonymised health data for everyone in all four nations of the UK, an advance which has only become possible during the pandemic. The researchers say that this approach could be extended to many other areas of medicine with great potential for new discoveries in the understanding and treatment of disease.

Professor Sir Aziz Sheikh, Director of the Usher Institute at the University of Edinburgh, HDR UK Research Director and study co-lead, said: “Large-scale data studies have been critical to pandemic management, allowing scientists to make policy-relevant findings at speed. COVID-19 vaccines save lives. As new variants emerge, this study will help to pinpoint groups of our society and areas of the country where public health campaigns should be focused and tailored for those communities.”

Early COVID-19 vaccine rollout began strongly in the UK, with over 90% of the population over the age of 12 vaccinated with at least one dose by January 2022. However, rates of subsequent booster doses across the UK were not fully understood until now.

Scientists from England, Scotland, Northern Ireland and Wales studied securely-held, routinely collected NHS data from everyone over 5 years of age during June 1 to September 30 2022. All data was de-identified and available only to approved researchers.

Data from across the four countries was then pooled and harmonised – or made more uniform – a feat that was not possible until now. People were grouped by vaccine status, with under-vaccination defined as not having had all doses of a vaccine for which that a person was eligible.

The findings reveal that the proportion of people who were under-vaccinated on June 1st 2022 ranged between one third and one half of the population – 45.7% for England, 49.8% for Northern Ireland, 34.2% for Scotland and 32.8% Wales.

Mathematical modelling indicated that 7,180 hospitalisations and deaths out of around 40,400 severe COVID-19 outcomes during four months in summer 2022 might have been averted, if the UK population was fully vaccinated.

Under-vaccination was related to significantly more hospitalisations and deaths across all age groups studied, with under-vaccinated people over 75 more than twice as likely to have a severe COVID-19 outcome than those who were fully protected.

The highest rates of under-vaccination were found in younger people, men, people in areas of higher deprivation, and people of non-white ethnicity.

Researchers say the study – the largest ever study carried out in the UK – also ushers in a new era for UK science by overcoming challenges in uniting NHS data that is gathered and stored in different ways between devolved nations.

Professor Cathie Sudlow, Chief Scientist at Health Data Research UK and Director of the British Heart Foundation (BHF) Data Science Centre, said: “The infrastructure now exists to make full use of the potential of routinely collected data in the NHS across the four nations of the UK. We believe that we could and should extend these approaches to many other areas of medicine, such as cancer, heart disease and diabetes to search for better understanding, prevention and treatment of disease."

The study was set up to provide UK and devolved governments with data-driven insights into COVID-19 vaccination coverage and establish data pooling methods and infrastructure to pave the way for future UK-wide studies. It is led by HDR UK and the University of Edinburgh, in collaboration with research teams from across the four nations.

Alan Keys, a public contributor at the British Heart Foundation (BHF) Data Science Centre at HDR UK who sat on the steering group of the study and is a co-author on the paper, said: “The research outcome is a powerful validation of the benefits of vaccination.”

Ends

Notes to Editors:

For further information, copies of the paper or to request an interview with the researchers, contact the HDR UK Communications team at media@hdruk.ac.uk or +44 7594 514007
Once published, the study will be available at https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(23)02467-4/fulltext
Health Data Research UK is the national institute for health data that includes England, Wales, Scotland and Northern Ireland. Its mission is to unite the UK’s health data to enable discoveries that improve people’s lives. It is a charity funded by UK Research and Innovation, the Department of Health and Social Care in England and equivalents in Northern Ireland, Wales and Scotland, and leading medical research charities. www.hdruk.ac.uk
The British Heart Foundation (BHF) Data Science Centre is a partnership between Health Data Research UK (HDR UK) and the British Heart Foundation. We work closely with patients, the public, NHS organisations, researchers, and clinicians to promote the safe and ethical use of data for research into the causes, prevention and treatment of all diseases of the heart and circulation. https://bhfdatasciencecentre.org/
Read more about the HDR UK COALESCE study here: https://www.ed.ac.uk/usher/eave-ii/connected-projects/coalesce

JOURNAL

The Lancet

DOI

10.1016/S0140-6736(23)02622-3

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Undervaccination and severe COVID-19 outcomes: meta-analysis of national cohort studies in England, Northern Ireland, Scotland, and Wales

ARTICLE PUBLICATION DATE

15-Jan-2024

COI STATEMENT

Aziz Sheikh (ASh) reports being a member of the Scottish Government Chief Medical Officer’s COVID-19 Advisory Group, the Scottish Government’s Standing Committee on Pandemic Preparedness, the UK Government’s New and Emerging Respiratory Virus Threats Advisory Group Risk Stratification Subgroup, the Department of Health and Social Care’s COVID-19 Therapeutics Modelling Group, and AstraZeneca’s COVID-19 Strategic Thrombocytopenia Taskforce (all unfunded). Prof C Robertson (CR) reports being a member of the Scottish Government Chief Medical Officer’s COVID-19 Advisory Group, the Scientific Pandemic Influenza Group on Modelling, and the Medicines and Healthcare Products Regulatory Agency’s Vaccine Benefit and Risk Working Group. Declan T Bradley (DTB) reports being a member of the Scientific Pandemic Influenza Group on Modelling and the COVID-19 Scientific Advisory Group for Emergencies and its subgroups. Kamlesh Khunti (KK) reports being chair of the ethnicity subgroup of, and a member of, the UK Scientific Advisory Group for Emergencies. RAL reports being a member of the Welsh Government COVID-19 Technical Advisory Group. All other authors declare no competing interests.

Key moment in the evolution of life on Earth captured in fossils

Peer-Reviewed Publication

CURTIN UNIVERSITY

Curtin-led research has for the first time precisely dated some of the oldest fossils of complex multicellular life in the world, helping to track a pivotal moment in the history of Earth when the seas began teeming with new lifeforms - after four billion years of containing only single-celled microbes.

Lead author PhD student Anthony Clarke, from the Timescales of Mineral Systems Group within Curtin’s School of Earth and Planetary Sciences, said to determine the age of the fossils, researchers used volcanic ash layers like bookmarks in the geological sequence.

“Located in the Coed Cochion Quarry in Wales, which contains the richest occurrence of shallow marine life in Britain, we used outfall from an ancient volcano that blanketed the animals as a time marker to accurately date the fossils to 565 million years, accurate down to 0.1 per cent,” Mr Clarke said.

“With similar Ediacaran fossils found at sites around the world including in Australia, dating the fossils identifies them as being part of an ancient living community that developed as Earth thawed out from a global ice age.

“These creatures would in some ways resemble modern day marine species such as jellyfish, yet in other ways be bizarre and unfamiliar. Some appear fern-like, others like cabbages, whereas others resembled sea pens.”

Study co-author Professor Chris Kirkland, also from the Timescales of Mineral Systems Group at Curtin, said the fossils are named after the Ediacara Hills in South Australia’s Flinders Ranges, where they were first discovered, leading to the first new geological period established in over a century.

“These Welsh fossils appear directly comparable to the famous fossils of Ediacara in South Australia,” Professor Kirkland said.

“The fossils, including creatures like the disc-shaped Aspidella terranovica, showcase some of the earliest evidence of large-scale multicellular organisms, marking a transformative moment in Earth’s biological history.

“Ediacaran fossils record the response of life to the thaw out from a global glaciation, which shows the deep connection between geological processes and biology.

“Our study underscores the importance of understanding these ancient ecosystems in order to unravel the mysteries of Earth’s past and shape our comprehension of life’s evolution.”

Available online here once published, the full research paper, ‘U–Pb zircon-rutile dating of the Llangynog Inlier, Wales: constraints on an Ediacaran shallow 1 marine fossil assemblage from East Avalonia’ will appear in the.Journal of the Geological Society (JGS), which is owned and published by the Geological Society of London. JGS publishes topical, innovative and interdisciplinary research with global reach across the full range of Earth and planetary sciences.

JOURNAL

Journal of the Geological Society

DOI

10.1144/jgs2023-081

METHOD OF RESEARCH

Imaging analysis

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

U–Pb zircon-rutile dating of the Llangynog Inlier, Wales: constraints on an Ediacaran shallow 1 marine fossil assemblage from East Avalonia’

ARTICLE PUBLICATION DATE

15-Jan-2024

Pacific kelp forests are far older that we thought

32-million-year-old fossil holdfasts show kelp far predate animals we see in kelp forests today

Peer-Reviewed Publication

UNIVERSITY OF CALIFORNIA - BERKELEY

X-ray scan of fossil kelp holdfast — IMAGE:
AN X-RAY RECONSTRUCTION OF A 32-MILLION-YEAR-OLD FOSSIL KELP HOLDFAST COLORED TO SHOW THE BASE (ORANGE), HOLDFAST (YELLOW) AND THE BIVALVE SHELL TO WHICH IT ATTACHED (BLUE).
view more
CREDIT: DULA PARKINSON/ADVANCED LIGHT SOURCE, LAWRENCE BERKELEY NATIONAL LABORATORY

The unique underwater kelp forests that line the Pacific Coast support a varied ecosystem that was thought to have evolved along with the kelp over the past 14 million years.

But a new study shows that kelp flourished off the Northwest Coast more than 32 million years ago, long before the appearance of modern groups of marine mammals, sea urchins, birds and bivalves that today call the forests home.

The much greater age of these coastal kelp forests, which today are a rich ecosystem supporting otters, sea lions, seals, and many birds, fish and crustaceans, means that they likely were a main source of food for an ancient, now-extinct mammal called a desmostylian. The hippopotamus-sized grazer is thought to be related to today's sea cows, manatees and their terrestrial relatives, the elephants.

"People initially said, “We don't think the kelps were there before 14 million years ago because the organisms associated with the modern kelp forest were not there yet,’" said paleobotanist Cindy Looy, professor of integrative biology at the University of California, Berkeley. "Now, we show the kelps were there, it's just that all the organisms that you expect to be associated with them were not. Which is not that strange, because you first need the foundation for the whole system before everything else can show up."

Evidence for the greater antiquity of kelp forests, reported this week in the journal Proceedings of the National Academy of Sciences, comes from newly discovered fossils of the kelp’s holdfast — the root-like part of the kelp that anchors it to rocks or rock-bound organisms on the seafloor. The stipe, or stem, attaches to the holdfast and supports the blades, which typically float in the water, thanks to air bladders.

Looy's colleague, Steffen Kiel, dated these fossilized holdfasts, which still grasp clams and envelop barnacles and snails, to 32.1 million years ago, in the middle of the Cenozoic Era, which stretches from 66 million years ago to the present. The oldest previously known kelp fossil, consisting of one air bladder and a blade similar to that of today's bull kelp, dates from 14 million years ago and is in the collection of the University of California Museum of Paleontology (UCMP).

"Our holdfasts provide good evidence for kelp being the food source for an enigmatic group of marine mammals, the desmostylia," said Kiel, lead author of the paper and a senior curator at the Swedish Museum of Natural History in Stockholm. "This is the only order of Cenozoic mammals that actually went extinct during the Cenozoic. Kelp had long been suggested as a food source for these hippo-sized marine mammals, but actual evidence was lacking. Our holdfasts indicate that kelp is a likely candidate."

According to Kiel and Looy, who is the senior author of the paper and UCMP curator of paleobotany, these early kelp forests were likely not as complex as the forests that evolved by about 14 million years ago. Fossils from the late Cenozoic along the Pacific Coast indicate an abundance of bivalves — clams, oysters and mussels — birds and sea mammals, including sirenians related to manatees and extinct, bear-like predecessors of the sea otter, called Kolponomos. Such diversity is not found in the fossil record from 32 million years ago.

"Another implication is that the fossil record has, once again, shown that the evolution of life — in this case, of kelp forests — was more complex than estimated from biological data alone," Kiel said. "The fossil record shows that numerous animals appeared in, and disappeared from, kelp forests during the past 32 million years, and that the kelp forest ecosystems that we know today have only evolved during the past few million years."

The value of fossil hunting amateurs

The fossils were discovered by James Goedert, an amateur fossil collector who has worked with Kiel in the past. When Goedert broke open four stone nodules he found along the beach near Jansen Creek on the Olympic Peninsula in Washington, he saw what looked like the holdfasts of kelp and other macroalgae common along the coast today.

Kiel, who specializes in invertebrate evolution, agreed and subsequently dated the rocks based on the ratio of strontium isotopes. He also analyzed oxygen isotope levels in the bivalve shells to determine that the holdfasts lived in slightly warmer water than today, at the upper range of temperatures found in modern kelp forests.

Looy reached out to co-author Dula Parkinson, a staff scientist with the Advanced Light Source at Lawrence Berkeley National Laboratory, for help obtaining a 3D X-ray scan of one of the holdfast fossils using Synchrotron Radiation X-ray Tomographic Microscopy (SRXTM). When she reviewed the detailed X-ray slices through the fossil, she was amazed to see a barnacle, a snail, a mussel and tiny, single-celled foraminifera hidden within the holdfast, in addition to the bivalve on which it sat.

Looy noted, however, that the diversity of invertebrates found within the 32-million-year-old fossilized holdfast was not as high as would be found inside a kelp holdfast today.

"The holdfasts are definitely not as rich as they would be if you would go to a kelp ecosystem right now," Looy said. "The diversifying of organisms living in these ecosystems hadn't started yet."

Kiel and Looy plan further studies of the fossils to see what they reveal about the evolution of the kelp ecosystem in the North Pacific and how that relates to changes in the ocean-climate system.

Other co-authors of the paper are Rosemary Romero, a specialist in algae who obtained her Ph.D. from UC Berkeley in 2018 and is now an environmental scientist with the California Department of Fish and Wildlife; paleobotanist Michael Krings at Ludwig-Maximilians-Universität in Munich, Germany; and former UC Berkeley undergraduate Tony Huynh. Goedert is a research associate at the Burke Museum of Natural History and Culture at the University of Washington, Seattle.

A slice through a 32-million-year-old fossil holdfast showing the finger-like haptera overgrowing a barnacle.

CREDIT

Steffen Kiel

This timeline depicts the evolution of kelp forests and associated organisms along the Pacific Coast over the past 32 million years, along with water temperature variations. Black bars indicate members of the modern, complex kelp ecosystems — sea otters, abalone, sea urchins and, until recently, sea cows. The green bars indicate now-extincct members of early kelp beds, including desmostylians and penguin-like plotopterids.

CREDIT

Steffen Kiel and Cindy Looy

JOURNAL

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2317054121

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Early Oligocene kelp holdfasts and stepwise evolution of the kelp ecosystem in the North Pacific

ARTICLE PUBLICATION DATE

16-Jan-2024

Climate change threatens global forest carbon sequestration, study finds

Peer-Reviewed Publication

UNIVERSITY OF FLORIDA

Climate change is reshaping forests differently across the United States, according to a new analysis of U.S. Forest Service data. With rising temperatures, escalating droughts, wildfires, and disease outbreaks taking a toll on trees, researchers warn that forests across the American West are bearing the brunt of the consequences.

The study, led by UF Biology researchers J. Aaron Hogan and Jeremy W. Lichstein was published in the Proceedings of the National Academy of Sciences. The study reveals a pronounced regional imbalance in forest productivity, a key barometer of forest health that gauges tree growth and biomass accumulation. Over the past two decades, the Western U.S., grappling with more severe climate change impacts, has exhibited a notable slowdown in productivity, while the Eastern U.S., experiencing milder climate effects, has seen slightly accelerated growth.

Forests play a critical role in regulating the Earth’s climate, acting as carbon sinks that sequester approximately 25% of human carbon emissions annually. However, their ability to store carbon hinges on the delicate balance between the positive and negative effects of climate change. The study, using national-scale forest inventory data, models trends from 1999 to 2020, analyzing 113,806 measurements in non-plantation forests.

“We are witnessing changes in forest functioning as forest ecosystems respond to global change drivers, such as carbon-dioxide-fertilization and climate change,” said Hogan. “It is the future balance of these drivers which will determine the functioning of forests in the coming years to decades.”

Some drivers, such as droughts and forest pathogens, have negative effects on productivity, but other drivers, such as carbon-dioxide fertilization, are predicted to have positive effects. This phenomenon suggests that increased carbon-dioxide levels enhance plant growth by increasing photosynthesis, which inspired the researchers to take a deeper look at its impact.

“The U.S. Forest Service has been monitoring the growth and survival of over a million trees across the U.S. for multiple decades,” said Lichstein. “We were interested to see if their data provided evidence for increased rates of tree growth, as predicted by the carbon-dioxide fertilization hypothesis.”

While tree growth in the Eastern U.S. aligns with expectations, the Western region shows extreme climate effects overshadowing any positive growth trends, challenging the prevailing assumption that forests’ carbon-storing ability will continue to increase.

“Our study suggests that future projections of climate and sea-level rise may be too optimistic because, in reality, ecosystems are likely to store less carbon in the future,” said Lichstein. “Less ecosystem carbon storage means more carbon in the atmosphere and therefore more warming and accelerating climate change.”

The findings also illuminate the fact that climate change is not a uniform force but rather a dynamic agent with region-specific influences. The study illustrates how the degree of climate change can push forests past a tipping point. Some forests are already approaching or surpassing climate thresholds which shift them to become sources of carbon, rather than sinks that remove carbon from the atmosphere.

“Ecosystem carbon sequestration is not guaranteed to be permanent, and it can be reversed by climate change,” said Lichstein. “This reversal is already happening in the Western U.S., and there are signs that it may also be happening in other drought-impacted regions of the world, such as the Amazon.”

It might be tempting to chalk the losses up to extreme events. But, according to the researchers, the decline in productivity in the Western U.S. cannot be attributed to increased rates of tree mortality.

“We hear a lot about wildfires in the Western U.S., which kill a lot of trees and release carbon to the atmosphere,” said Lichstein. “But our study shows that additional ecosystem carbon loss in Western forests is occurring due to declining tree growth rates.”

With trees growing slower due to adverse climate change effects, including decreased precipitation, the study implies that, even without the intensifying wildfires, the carbon sink in Western forests will continue to weaken without urgent action to reduce human greenhouse gas emissions.

“We must have healthy forests in connection with emissions reduction to restore the global carbon balance and limit climate change,” said Hogan.

The transformations observed in U.S. forests raise concerns about their future resilience and sustainability. The researchers hope their findings highlight the urgent need for governments and industry to work together to reduce greenhouse gas emissions and achieve net-zero emissions as soon as possible.

“Our results highlight the need for reduced global greenhouse gas emissions,” said Lichstein. “Without the emissions reductions that scientists have been urging for decades, forest carbon sinks will likely weaken, which will accelerate the pace of climate change.”

This study was developed with Grant Domke from the U.S. Forest Service Northern Research Station, Kai Zhu from the University of Michigan, and Dan Johnson from UF’s School of Forest, Fisheries, and Geomatics Sciences.

JOURNAL

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2311132121

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Climate change determines the sign of productivity trends in US forests

ARTICLE PUBLICATION DATE

15-Jan-2024