Dog–owner interaction is reflected in heart rate variability

University of Jyväskylä - Jyväskylän yliopisto

 

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Research clarifies the mechanisms of human-dog interaction.

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Credit: University of Jyväskylä

Emotional connection enhances interaction in human relationships. Emotional synchronisation in the interaction between a child and a parent is essential for affective attachment. The relationship between a dog and its owner is also based on attachment, but little is known about its physiological mechanisms.

 

The heart rate variability of a dog and its owner adapt to each other

In a study conducted at the University of Jyväskylä, at the Department of Psychology and Jyväskylä Centre for Interdisciplinary Brain Research, it was found that the heart rate variability of a dog and its owner are interconnected during interaction. Heart rate variability, in other words, the variation in the heartbeat intervals, indicates the state of the autonomic nervous system. High heart rate variability is associated with a state of relaxation and recovery, while low heart rate variability indicates stimulation or strain, such as stress during an exam or sport performance. In this study, the owner’s high heart rate variability was connected to the dog’s high heart rate variability, and vice versa. In addition, the physical activity levels of a dog and its owner mutually adapted to each other during the study.

 

Different connections for activity and heart rate variability

The connections of heart rate variability and activity levels between a dog and its owner were monitored during specific interaction tasks. Both heart rate and activity level were interconnected between dogs and their owners, but at different times. During free-form resting periods, the owner’s high heart rate variability was connected to the dog’s high heart rate variability. In other words, when the owner was relaxed the dog was also relaxed. Moreover, the owner’s and dog’s activity levels were similar during the given tasks, such as playing. Although it is known that physical activity has an impact on heart rate, the strongest connections of these variables between dog and owner were found in different situations and do not fully explain each other. This suggests that the connection in heart rate variability reflects the synchrony of emotional state rather than of activity levels.

“The interconnection in heart rate variability between the dog and its owner during resting periods may be explained by the fact that in those instances there were no external tasks, but the counterparts could react more to each other’s state in a natural way,” says Doctoral Researcher Aija Koskela.

 

Owner’s temperament is connected to the dog’s heart rate variability

The study also investigated various background factors for the interconnection of the heart rate variability of the dog and its owner. Bigger dogs had higher heart rate variability. In addition, the dog’s high heart rate variability was also explained by the owner’s negative affectivity, a temperament trait that reflects the person’s tendency to become easily concerned about negative things. This type of owner tends to develop a strong emotional bond with the dog, and therefore the shepherd dogs of this study possibly had a higher sense of safety with these owners.

 

The dog also influences the owner

A surprising finding in the study was that the owner’s heart rate variability was best explained by the dog’s heart rate variability, even though also the owner’s activity level and body mass index, which are known to impact heart rate, were taken into account in the analysis.

“We exceptionally investigated both a dog’s and its owner’s heart rate and activity level simultaneously, whereas previous studies have commonly focused either on the human’s or the dog’s perspective,” says the leader of the study, Academy Research Fellow Miiamaaria Kujala. “The challenging research setting gives a better opportunity to investigate interactive aspects.”

This study indicates that the emotional states of dogs and their owners as well as the reactions of their nervous system become partially adapted to each other during interaction. The same mechanisms that strengthen human affective attachment also seem to support the relationship between a dog and its owner. This study deepens our understanding about interaction between species and about the meaning of emotional connection between dogs and humans.

 

Interaction research involved dogs bred for cooperation

The study was funded mainly by the Research Council of Finland and the Agria & Svenska Kennelklubben Research Fund. It involved altogether 30 voluntary dog owners with their dogs. The dogs represented breeds refined for cooperating with humans, such as sheep dogs and retrievers. The research findings are in line with previous studies, which have suggested that breeds selected for cooperation are particularly sensitive to react to their owners’ behaviour and personality traits. Next, the project will seek to shed light more specifically on the influential mechanisms involved in this phenomenon.

The study was published on 24 October 2024 in Scientific Reports:

Koskela, A., Törnqvist, H., Somppi, S. et al. Behavioral and emotional co-modulation during dog–owner interaction measured by heart rate variability and activity. Sci Rep 14, 25201 (2024). https://doi.org/10.1038/s41598-024-76831-x

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Journal

Scientific Reports

DOI

10.1038/s41598-024-76831-x 

Subject of Research

People

Article Title

Behavioral and emotional co-modulation during dog–owner interaction measured by heart rate variability and activity

Mechanosensory origins of “wet dog shakes” – a tactic used by many hairy mammals – uncovered in mice

Summary author: Walter Beckwith

American Association for the Advancement of Science (AAAS)

“Wet dog shakes” – a common reflex behavior shared among many hairy mammals and designed to expel water and irritants from their coats – happens when particular mechanoreceptors are activated, researchers studying mice report. Many furry mammals engage in rapid body twists known as "wet dog shakes" to effectively remove water from their fur, as well as to eliminate irritants like tangles or parasites, particularly in areas on the neck and back that are largely unreachable by self-grooming or licking. However, despite the commonality of this behavior across species, the neural mechanisms underlying these shakes have remained largely unexplored. Using combined optogenetic, physiological, and behavioral approaches, Dawei Zhang and colleagues evaluated the neurobiological foundations of the wet dog shake behavior in mice. Zhang et al. found that mechanosensation mediated by the Piezo2 gene is essential for the wet dog shake response evoked by oil droplets applied to the backs of mice. According to the findings, mechanoreceptors known as “C-LTMRs,” which primarily innervate the hair follicles of the undercoat, are the key sensory players in this behavior. C-LTMRs, which are typically involved with pleasant affective touch, are connected to spinoparabrachial neurons that transmit sensory signals to the parabrachial nucleus in the brainstem. The authors found that optogenetic activation of C-LTRMs also elicited wet dog shakes without applying oil droplets. Moreover, inhibiting spinoparabrachial neuron synapses and excitatory neurons in the parabrachial nucleus disrupts the wet dog shake response triggered by both oil droplets and C-LTMR activation.

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Journal

Science

DOI

10.1126/science.adq8834 

Article Title

C-LTMRs evoke wet dog shakes via the spinoparabrachial pathway

Article Publication Date

8-Nov-2024

Low latency carbon budget analysis reveals a large decline of the land carbon sink in 2023

Science China Press

 

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(a) Growth rate from marine boundary layer surface stations (MBL, blue bars) and the Mauna Loa station (MLO, dark blue squares). (b) Global CO2 budget obtained with historical fossil fuel and cement CO2 emissions and our estimates of land and ocean sinks in 2023, and the MBL / MLO CO2 annual growth rates. Our estimates are based on simulations by emulators of the ocean sink, simulations of the land sink by three dynamic vegetation models forced by low latency climate input data (their mean sink in 2019-2022 being adjusted to equal the median of 16 models used in the latest Global Carbon Budget edition). The ocean and land sinks in the inside bars are from the OCO-2 high resolution atmospheric inversion. The difference between the stacked bars at the bottom and the red curve (-1 x Fossil emissions) is the imbalance of the budget.

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Credit: ©Science China Press

In 2023, global land carbon sinks—the Earth’s forests, soils, and vegetation that absorb CO2—experienced a dramatic decline, as revealed by a study published in National Science Review by several international research teams. Using dynamic global vegetation models, satellite fire emissions, OCO-2 satellite measurements, and ocean model emulators, the study provides a fast-track carbon budget for 2023, identifying unprecedented weakening of land carbon sinks.

“In 2023 the accumulation of CO2 in the atmosphere is very high and this translates into a very, very low absorption by the terrestrial biosphere,” says Philippe Ciais, a researcher at the French Laboratory of Climate and Environmental Sciences, who was an author of the most recent paper. “In the northern hemisphere, where you have more than half of CO2 uptake, we have seen a decline trend in absorption for eight years,” he says. “There is no good reason to believe it will bounce back.”

The land sink dropped to 0.44 ± 0.21 GtC yr-1, driven by extreme heat, wildfires, and a moderate El Niño. Particularly, Canadian wildfires contributed 0.58 ± 0.10 GtC, while the Amazon drought caused an additional 0.31 ± 0.19 GtC loss.

Despite the decline on land, the ocean sink increased slightly by 0.10 GtC yr-1 compared to 2022, largely due to El Niño suppressing CO2 emissions in the Pacific Ocean. However, the rapid reduction in land carbon sink raises concerns about future climate stability, as the models used for climate predictions may not fully account for such sudden shifts in carbon sinks.

The findings underscore the importance of strengthening global carbon sequestration efforts. The authors call for urgent measures to protect and enhance carbon sinks, alongside drastic reductions in fossil fuel emissions, to avoid further destabilization of the climate system.

Net land and ocean CO2 flux anomalies for each quarter in 2023 compared with the 2015-2022 average for bottom-up models (left column) and the OCO-2 inversion (right column). 

Positive values represent increased flux from the atmosphere to the land or ocean (carbon sink).

Credit

©Science China Press

See the article:

Low latency carbon budget analysis reveals a large decline of the land carbon sink in 2023

https://doi.org/10.1093/nsr/nwae367

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Journal

National Science Review

DOI

10.1093/nsr/nwae367 

Scientists predicted the spatial-temporal dynamics of soil microbial-derived carbon stocks

Science China Press

 

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(a) Global map of the predicted MDC stock distribution for the year 2018, along with the changes from 1981 to 2018. The white areas in the left panel and the dark areas in the right panel are the areas with low confidence projections. (b) The relative rates of change in MDC stocks as percentages per annum and per degree Celsius. The dark areas are the areas with low confidence projections. (c) Status of MDC stocks between 1981 and 2018. Bivariate plot comparing the relative rate of change in MDC stock (% per year) against the quantity of MDC stocks. The status categories for the rate of change were determined using confidence intervals, while the MDC stock status groups were established based on quantile distributions (divided into three equal parts). The white areas are the areas with low confidence projections.

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Credit: ©Science China Press

Soil organic carbon (SOC) is the largest carbon pool in terrestrial ecosystems and plays a crucial role in mitigating climate change and enhancing soil productivity. Microbial-derived carbon (MDC), accounting for about half of the total SOC pool, is the main component of the persistent SOC pool. However, our limited understanding of the spatial and temporal dynamics of MDC stocks at the global scale hampers our ability to assess the long-term effects of global warming on persistent SOC sequestration.

To fill this gap, the research team led by Jiabao Zhang and Yuting Liang, researchers at the Nanjing Institute of Soil Science, Chinese Academy of Sciences, in collaboration with Shenyang Institute of Applied Ecology, Aarhus University (Denmark), University of Kassel (Germany), ETH Zurich (Switzerland), University of Oklahoma (USA), and other domestic and foreign research units, predicted the spatial-temporal dynamics of soil microbial-derived carbon stocks. The relevant research results are described as " Global decline in microbial-derived carbon stocks with climate warming and its future projections", published online in National Science Review.

In this study, this team compiled an extensive global dataset and employed ensemble machine learning techniques to forecast the spatial-temporal dynamics of MDC stocks across 93.4% of the total global land area from 1981 to 2018. This work revealed that for every 1°C increase in temperature, there was a global decrease of 6.7 Pg in the soil MDC stock within the predictable areas, equivalent to 1.4% of the total MDC stock or 0.9% of the atmospheric C pool. The tropical regions experienced the most substantial declines in MDC stocks. They further projected future MDC stocks for the next century based on shared socioeconomic pathways, showing a global decline in MDC stocks with a potential 6-37 Pg reduction by 2100 depending on future pathways.

MDC is crucial for maintaining the long-term stability of SOC. A decrease in MDC suggests that a substantial portion of the stable SOC could be released into the atmosphere as carbon dioxide (CO2), creating a positive feedback loop between atmospheric and soil carbon reservoirs.“These results offer an empirical foundation for refining the temperature dependency of MDC stocks within atmosphere‒soil carbon cycle models.” Liang says.

This study underscores that global warming will lead to a decrease in global MDC stocks, which could have severe ecological repercussions for climate change, food security, and ecosystem integrity. The researchers recommend integrating the response of MDC stocks to warming into socioeconomic models to enhance confidence in selecting sustainable pathways.

Projections of the total global microbial-derived carbon (MDC) stock under various shared socioeconomic pathways 

SSP126 represents a sustainability scenario in which the world is gradually transitioning toward sustainable practices. SSP245, the middle-of-the-road scenario, maintains trends closely aligned with historical patterns. SSP370, the regional rivalry scenario, emphasizes domestic or regional issues due to increased nationalism and conflicts. Finally, SSP585 is a fossil-fueled development scenario characterized by large-scale exploitation of fossil fuels that intensifies environmental degradation and climate change.

Credit

©Science China Press

See the article:

Global decline in microbial-derived carbon stocks with climate warming and its future projections

https://doi.org/10.1093/nsr/nwae330

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Journal

National Science Review

DOI

10.1093/nsr/nwae330 

 

How much climate change is in the weather?

New AWI simulations make it possible to compare actual extreme weather events in various climate scenarios, and to gauge the role of global warming in connection with these extremes in the process.

Peer-Reviewed Publication

Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research

 

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Precipitation amounts from storm "Boris" from 12 to 16 September 2024.

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Credit: Alfred Wegener Institute / Marylou Athanase

Only a few weeks ago, massive precipitation produced by the storm “Boris” led to chaos and flooding in Central and Eastern Europe. An analysis conducted by the Alfred Wegener Institute shows that in a world without the current level of global warming Boris would have deposited roughly nine percent less rain. Such conclusions can be drawn thanks to a new modelling approach called ‘storylines’. How it can be used in near-real-time was just presented in the Nature journal Communications Earth & Environment. At the same time, the AWI team released a freely available online tool that allows users to identify the fingerprints of climate change in current extreme weather events and create their own comparison graphics.

In mid-September, the storm “Boris” produced torrential rains and extreme flooding in Poland, the Czech Republic, Austria and Romania. In many of the affected regions, it was one of the highest amounts of precipitation ever recorded in a five-day period. There were at least 27 fatalities, while countless families were forced to leave their homes. In the meantime, the situation has improved and cleanup efforts are running round the clock. But already the next weather extremes, this time in Spain, are cause for concern. Time and time again, a central question arises in public, political, and media forums: was the catastrophe caused by global climate change?

“For the past few years, science has been able to provide robust answers to this absolutely legitimate question,” says lead author Dr Marylou Athanase, a physicist in the Climate Dynamics Section of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). “As early as one or two weeks after a given event, so-called probabilistic attribution studies can be used to draw initial conclusions on how much more probable the event was, due to climate change.”

The only problem: probabilities are often somewhat intangible, especially when they collide with concrete and exceptional, real-world events. When it comes to external communications – with the public and decision-makers – the scientific community has never had a tool that could show the influence of global climate change on the actual local weather in an impressive yet readily understandable way. “That’s why we at the AWI have worked so hard to advance a totally new way – the ‘storyline’ approach,” explains Dr Antonio Sánchez-Benítez, a fellow physicist in the Climate Dynamics Section and co-lead author of the study. “Essentially, we apply the ‘what if?’ principle. What would a given catastrophe look like in a world without climate change? And what about in a climate that was even warmer? By comparing the hypothetical scenarios with the reality, we can then very clearly identify the fingerprints of climate change – and not just for extreme weather events, but also for day-to-day weather.”

Using storm Boris as an example, the AWI experts have now demonstrated what the new approach can do in the Nature journal Communications Earth & Environment. A comparison of the scenarios shows: without global warming, Boris would have deposited roughly nine percent less rain. In reality, however, on its way from the eastern Mediterannean and the Black Sea toward Central Europe, the storm was able to gather in intensity because the water was roughly two degrees Celsius warmer than preindustrial levels – which meant a correspondingly higher percentage of water vapour in the air above the region. Nine percent might not sound like much, but when it comes to the consequences of heavy rains, it always comes down to how much water gathers on the surface and where it all goes – can a river, a dam, or a sewage system hold it, or does it spill over, doing tremendous damage in the process?

But how did the experts manage to connect climate model-based simulations, which are mainly designed for long-term trends, with the actual local weather? “One important aspect is what is known as ‘nudging’”, explains Dr Helge Gößling, a climate physicist and team lead of the storyline research at the AWI. “Climate models normally simulate a specific, quasi-random sequence of weather conditions, which is consistent with the laws of physics that their programming is based on. In order to identify differences in the climate, you need to see whether the mean values and distributions change, over a long period of time with a correspondingly large number of weather conditions. Likewise, in weather models the simulated conditions have very little to do with the reality after a few weeks; the actual weather can only be predicted to a limited extent. With the ‘nudging’, we provide the model with actually observed wind data, including phenomena like the jet stream, and we nudge the model a bit in the direction of the actually observed wind. In this way, we can accurately reproduce real weather in the real climate. Then we change the background climate of the model, for instance to a world untouched by climate change by reducing the greenhouse-gas concentrations and adjusting other aspects, and repeat the experiment.”

The model used is the CMIP6 version of the AWI climate model, which was also part of the base data for the IPCC’s Sixth Assessment Report. The wind data fed into the model stems from the ERA5 reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). “We have since automated the system to the point where daily analyses on the current weather are run on the supercomputer at the German Climate Computing Center (DKRZ),” says Marylou Athanase. “The data is then transferred to an online tool that runs on the AWI’s servers and is freely accessible to everyone at https://climate-storylines.awi.de. The analyses are conducted with a three-day delay on ‘real-time’, after which they’re available online. As a result, interested users can log on anytime to see the ‘Climate Change Signal of the Day’ for extremes and everyday weather, around the globe and in near-real-time, in the form of interactive maps and timelines, though for the time being, only data on the temperature and precipitation from 1 January 2024 onwards is available. Our goal is to promote a better understanding of the connections between climate change and extreme weather events, and to supply concrete and timely answers that can also be used in media coverage of these events.”

 

Precipitation Observations and Simulations 

 

Precipitation amounts of storm "Boris" from 12 to 16 September 2024 in (a) observations and (b) simulation (in millimetres). The simulated change in precipitation due to climate change to date is shown in (c), the simulated further change in the course of a possible strong additional warming is shown in (d).

Credit

Alfred Wegener Institute / Marylou Athanase

Original publication:

Marylou Athanase, Antonio Sánchez-Benítez, Eva Monfort, Thomas Jung, Helge F. Goessling (2024). How climate change intensified storm Boris’ extreme rainfall, revealed by near-real-time storylines. Nature Communications Earth & Environment; DOI: https://doi.org/10.1038/s43247-024-01847-0

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DOI

10.1038/s43247-024-01847-0 

Method of Research

Computational simulation/modeling

Subject of Research

Not applicable

Article Title

How climate change intensified storm Boris’ extreme rainfall, revealed by near-real-time storylines

Article Publication Date

8-Nov-2024

 

“Allegations of maladaptation harm the poor”

World climate conference: Prof. Lisa Schipper from the University of Bonn urges fairness in the Journal "Science"

University of Bonn

 

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from the Institute of Geography at the University of Bonn. 

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Credit: Photo: Friederike Pauk/GIUB

Countries continue to debate adaptation to climate change: How should such strategies be financed? Who pays for them? How should the success of these measures be measured and their failure avoided? “If political decision-makers claim that it is impossible to measure the success of adaptation measures due to their complexity, this can have an impact on the financing of such measures,” warns Prof. Dr. Lisa Schipper from the Department of Geographical Development Research at the University of Bonn.

Adequate funding is linked to progress in adaptation. Many countries in the Global North support a view that questions the usefulness and accuracy of adaptation indicators. “Without such indicators, however, the countries of the Global South fear that their arguments for funding will come to nothing,” says Schipper.

Plenty of examples of improvements

Maladaptation – when adaptation measures backfire and make people worse off in the face of climate change – are most often the result of poor planning and implementation, the two researchers write. It is also problematic when external donors lack an understanding of the context. However, considerable investments have been made in adaptation measures worldwide over the last ten years and these have also been implemented. “There are enough examples available for evaluation and improvement,” says Schipper.

As an example, the scientists cite the fact that irrigation is often generally referred to as maladaptation because this can lead to an unequal distribution of this resource and promote water-intensive cultivation systems. “However, this is not a problem if appropriate crops suited to overall ecology and water endowments are grown using irrigation, problem arises when water intensive crops are grown in water scarce regions using irrigation,” according to Aditi Mukherji from CGIAR, who works on irrigation in the Global South. Furthermore, irrigation in poor agricultural areas can provide the population with necessary food. If labeled as maladaptation in advance, the benefits of irrigation may be ignored and this could remove an important mechanism for improving development and well-being for many people around the world.

What makes people vulnerable to climate change?

The discussion rarely addresses what makes people vulnerable to climate change in the first place. Factors such as the exclusion of certain social groups due to their ethnicity, religion or political beliefs are often ignored. However, those affected are forced to live in areas that are more frequently affected by flooding. Instead of avoiding these areas for settlements, early warning systems would be installed.

“Maladaptation should be understood as a cautionary tail and a roadmap for adaptation improvements,” the two authors conclude. A climate reparations agenda would provide funding for those most affected by climate change without imposing strict conditions on funding. After all, those who most urgently need adaptation funding bear the least responsibility for climate change.

“The UNEP estimates that hundreds of billions US dollar need to be raised annually for such adaptation measures,” says Aditi Mukherji referring to the recently published ‘Adaptation Gap Report 2024’ by the United Nations Environment Programme (UNEP). “We are still a long way from this sum.”

“The task now is to ensure that the money that is spent is used effectively and carefully aligns with development needs and agendas to avoid maladaptive outcomes,” adds Schipper.

Publication: E.L.F. Schipper and A. Mukherji: Misguided negative adaptation narratives are hurting the poor, Science, DOI: 10.1126/science.adq7821, URL: https://www.science.org/doi/10.1126/science.adq7821

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Journal

Science

DOI

10.1126/science.adq7821 

Method of Research

Commentary/editorial

Subject of Research

People

Article Title

Misguided negative adaptation narratives are hurting the poor

Article Publication Date

7-Nov-2024

 

Nanoparticle bursts over the Amazon rainforest

Rainfall induces bursts of natural nanoparticles that can form clouds and further precipitation over the Amazon rainforest

Max Planck Institute for Chemistry

 

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A rain front approaches the ATTO research station in the Amazon rainforest.

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Credit: Sebastian Brill, Max Planck Institute for Chemistry

During the wet season in the Amazon rainforest heavy rainfall frequently occurs during the afternoon. For clouds and precipitation to develop, tiny airborne particles known as cloud condensation nuclei are required for water vapor to condense and form cloud droplets. But what are the origins of these cloud condensation nuclei?

An international research team from Germany, Brazil, Sweden, and China now showed that rainfall regularly induces bursts of nanoparticles that can grow to form cloud condensation nuclei. The scientists analyzed comprehensive long-term measurements of aerosol particles, trace gases, and meteorological data from the Amazon Tall Tower Observatory, ATTO, which is equipped with sophisticated instrumentation and measurement towers that are up to 325 m high. The observatory is located in the middle of the Amazon rainforest in northern Brazil, about 150 kilometers north-east of Manaus, and jointly operated by scientists from Germany and Brazil.

Luiz Machado, first author of the study now published in the journal Nature Geoscience, explains: “Rainfall removes aerosol particles and introduces ozone from the atmosphere into the forest canopy. Ozone can oxidize plant-emitted volatile organic compounds, especially terpenes, and the oxidation products can enhance the formation of new particles, leading to temporary bursts of nanoparticles.”

Nanoparticle concentrations are highest just above the forest canopy

The researchers discovered that nanoparticle concentrations are highest just above the forest canopy and decrease with increasing altitude. “This gradient persists throughout the wet season, indicating continuous particle formation in the canopy and an upward flux of newly formed particles that can grow by further uptake of low volatile molecules and serve as cloud condensation nuclei”, adds Christopher Pöhlker, co-author and research group leader at the Max Planck Institute for Chemistry. Among the low volatile molecules involved in the formation and growth of natural nanoparticles in the atmosphere are oxygen- and nitrogen-containing organic compounds that are formed upon oxidation of isoprene, terpenes, and other volatile organic compounds, which are naturally emitted by plants and oxidized by ozone and hydroxyl radicals in the air.

Earlier studies had detected new particle formation in the outflow of convective clouds in the upper troposphere and suggested a downward flux rather than an upward flux of newly formed nanoparticles.

“Our findings imply a paradigm shift in the scientific understanding of interactions between the rainforest, aerosols, clouds, and precipitation in the Amazon, which are important for regional and global climate”, concludes Ulrich Pöschl, co-author and director at the Max Planck Institute for Chemistry.

 

About ATTO:
The Amazon Tall Tower Observatory (ATTO) is an internationally collaborative research site in the central Amazon, dedicated to studying atmospheric processes and the exchange of energy, water, and gases between the biosphere and atmosphere. It is one of the world’s most critical observatories for understanding the impacts of climate change on tropical forests.

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Journal

Nature Geoscience

DOI

10.1038/s41561-024-01585-0 

Article Title

Frequent nanoparticle bursts in the Amazon rainforest

Article Publication Date

8-Nov-2024

 

Deep ocean clues to a million-year-old ice age puzzle revealed in new study

Woods Hole Oceanographic Institution

 

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Sediment core undergoing analysis on board the D/V JOIDES Resolution.

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Credit: Photo credit: Nina Rooks-Cast

Woods Hole, Mass. (Nov. 8, 2025) - A recently published study in Science challenges theories regarding the origins of a significant transition through the Earth’s ice ages. Led by an international team of researchers from the Woods Hole Oceanographic Institution (WHOI), the Lamont-Doherty Earth Observatory, the Scripps Institution of Oceanography, and Cardiff University, this research provides fresh insights into the ocean’s role in climate during the Mid-Pleistocene Transition, an enigmatic interval of change in climate cycles that began about one million years ago.

Many theories have been proposed for the Mid-Pleistocene Transition, and an important one is linked to a significant weakening of the Atlantic Meridional Overturning Circulation (AMOC). However, the new findings suggest an equally important but much more nuanced role for the deep ocean.

Using climate records spanning the past 1.2 million years, the team reconstructed deep ocean properties that are crucial for understanding the ocean’s flow and carbon sequestration capabilities. “The deep ocean is enormous, especially when considering its capacity to store carbon dioxide (CO2) compared to the atmosphere,” said lead author Dr. Sophie Hines, an Assistant Scientist at WHOI. “Even a modest change in ocean circulation could significantly impact global climate.”

The researchers analyzed sediment core samples collected during the International Ocean Discovery Program (IODP) Expedition 361 near Cape Town, South Africa. By studying carbon and oxygen from fossils of single-celled organisms called foraminifera and isotopes of neodymium, the team uncovered details about the changes in deep ocean temperature and salinity, as well as the mixing histories of waters originating in both the northern and southern hemispheres.

Dr. Sidney Hemming, the Arthur D. Storke Memorial Professor of Earth and Environmental Sciences at the Lamont-Doherty Earth Observatory and co-chief scientist on the expedition, said, “Crucially, we show that shifts in different deep ocean properties are not always coincident. With our more highly resolved multi-proxy record that includes transitional intervals, we find that ice age intensification was influenced primarily by changes around Antarctica.”

It is suggested that as the Antarctic Ice Sheet expanded, it enhanced the ocean's capacity to store carbon, leading to lower atmospheric CO2 levels, colder climates, and prolonged ice age cycles.

Dr. Hines added, “Our research sheds light on the intricate interplay between ocean dynamics and climate change, underscoring the significance of the Southern Ocean in understanding our planet's climate history.”

Recent studies stress the urgency of anthropogenic climate change, particularly in relation to reductions in the AMOC. As the Southern Ocean continues to warm at an alarming rate, understanding its dynamics is critical. The Southern Ocean plays a pivotal role in regulating global climate patterns, and its changes could have significant implications for ecosystems and weather systems worldwide. 

Dr. Sophie Hines (right) assists IODP-JRSO technician Sandra Herman (left) in cutting an Expedition 361 core into sections.

Credit

Photo credit: Tim Fulton.

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About Woods Hole Oceanographic Institution

Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment. For more information, please visit www.whoi.edu.

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Journal

Science

DOI

10.1126/science.adn4154 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Revisiting the mid-Pleistocene transition ocean circulation crisis

Article Publication Date

7-Nov-2024