GOOD LUCK WITH THAT

Possible to limit climate change to 1.5°C – if EU and 17 other countries go beyond their own targets

Stockholm University

 

image: 

Thomas Hahn, program director of the project Fair Transformation to a Fossil Free Future (FAIRTRANS) and Associate Professor at Stockholm Resilience Centre, Stockholm University. 
Photo: Ewa Malmsten Nordell.

view more 

Credit: Photo: Ewa Malmsten Nordell

A new study in Nature Communications finds that limiting global warming to 1.5 °C is still possible, but some countries require support to meet their climate responsibilities. An “additional carbon accountability” indicator is introduced, revealing that the EU and 17 other countries must exceed their own current targets to achieve this global goal.

The new study proposes an indicator – additional carbon accountability – that quantifies countries’ responsibility for mitigation and carbon dioxide removal in addition to achieving their own targets. Aside from further domestic reductions, this additional carbon accountability requires financing carbon removal, or emission reductions outside their territories.

A pressing question at the ongoing 29th annual UN Climate Conference (COP29) in Baku, Azerbaijan, is how to transition away from fossil fuels and speed up climate mitigation in line with the 1.5C global warming target. To address this, the new study by researchers from Stockholm University, Chalmers University of Technology, and Uppsala University, quantifies how much each country should reduce or remove carbon dioxide emissions beyond their current national commitments. 

“The ambition of this article is to suggest opportunities to enhance climate fairness and close the mitigation gap in the real world, based on the Paris Agreement,” says lead author Thomas Hahn, from the Stockholm Resilience Centre at Stockholm University. 

The study quantifies each country’s equal share of the remaining 1.5C carbon budget based on equal per capita historic emissions since 1990 and share of the remaining carbon budget. This is then compared to countries’ actual carbon debts and future emissions targets, creating an “additional carbon accountability” indicator. 

The study identifies 18 high-income and upper-middle-income countries that should be accountable for increasing their ambitions to stay within their equal per capita share of the global carbon budget for 1.5 °C. (Note that the EU is here counted as one country). Additional carbon accountability is highest for the United States and China, and highest per capita for the United Arab Emirates, Russia, Saudi Arabia and the United States.

“While there is no agreement on how to operationalize the fairness principles of the Paris Agreement, the new indicator provides an important tool to clarify the responsibility for the remaining mitigation gap in the context of the ongoing climate talks,” explains co-author Johannes Morfeldt from Physical Resource Theory, Department of Space, Earth and Environment, at Chalmers University of Technology.

In general, high-income countries have large carbon debts while several upper-middle income countries have high future emissions. Four of the 18 countries could theoretically fulfil their accountability with stricter domestic emission reductions. 

“14 of these 18 countries have a larger accountability than planned future emissions, meaning they would need to increase ambitions for carbon dioxide removal or for emission reductions in other countries, in addition to stricter emissions reductions,” says co-author Ingo Fetzer, from Stockholm Resilience Centre, Stockholm University.

As an example, besides reaching its 2030 reduction target and net zero by 2050, the EU would need to remove an additional 48 Gt carbon dioxide (gigatonnes, or billion metric tonnes) or finance additional reductions beyond current targets in other countries. For China, the additional carbon accountability is 150 Gt and the USA 167 Gt.

“Our study shows that it’s high time for the European Union to enhance its climate targets, instruments, and financing, to take responsibility for its fair share of a global carbon budget compatible with the Paris Agreement,” says co-author Mikael Karlsson from Climate Change Leadership, Department of Earth Sciences, at Uppsala University.

The study shows that the ability to pay is not uniform. Several BRICS+ nations, particularly Iran and Russia, may struggle economically to meet their additional responsibilities, in contrast to G7 members.

“Our results highlight that meeting the 1.5C target to a large extent is reliant on large historic emitters like the EU and the US paying off their historic carbon debts, and countries with plans for future large emissions, like China and Iran, setting stricter reduction targets,” adds co-author Robert Höglund.

More information:
The full paper is available for open access at Nature Communications https://www.nature.com/articles/s41467-024-54039-x  
Hahn, T., Morfeldt, J., Höglund, R., Karlsson, M., & Fetzer, I. (2024). Estimating countries’ additional carbon accountability for closing the mitigation gap based on past and future emissions. Nature Communications 15, 9707. 

Media contacts
Thomas Hahn, Program director of the project Fair Transformation to a Fossil Free Future (FAIRTRANS) and Associate Professor at Stockholm Resilience Centre, Stockholm University. 
thomas.hahn@su.se
Tel: +46 8 674 70 71

Mikael Karlsson, Associate Professor in Environmental Science and Senior Lecturer in Climate Change Leadership at Uppsala University.
mikael.karlsson@geo.uu.se
Tel: +46 70 316 27 22

Johannes Morfeldt, Researcher at Physical Resource Theory, Department of Space, Earth and Environment, at Chalmers University of Technology.
johannes.morfeldt@chalmers.se 
Tel: +46 31 772 14 67 

Robert Höglund
Marginal Carbon AB, Stockholm, Sweden
robert@marginalcarbon.com
Tel: +46 8 559 25 515

Ingo Fetzer, Researcher at Stockholm Resilience Centre, Stockholm University
ingo.fetzer@su.se
Tel: +49 73 707 8620

---

Journal

Nature Communications

DOI

10.1038/s41467-024-54039-x 

Method of Research

Data/statistical analysis

Subject of Research

Not applicable

Article Title

Estimating countries’ additional carbon accountability for closing the mitigation gap based on past and future emissions

Article Publication Date

9-Nov-2024

COI Statement

R.H. owns Marginal Carbon AB (consultancy in climate policy and carbon removal), which is a minority owner of CDR.fyi (carbon removal market data provider). R.H. holds paid advisory roles with Milkywire Climate Transformation Fund and Carbon Gap, and unpaid roles with the EU Expert Group on Carbon Dioxide Removal and SBTi Expert Advisory Group. These engagements have not influenced the research presented. Other authors declare no competing interests.

 

Decoding Deception: The Psychology of Combating Misinformation

Decoding Deception: The Psychology of Combating Misinformation, a short film produced by Proceedings of the National Academy of Sciences with support from the Pulitzer Center.

Proceedings of the National Academy of Sciences

Decoding Deception: The Psychology of Combating Misinformation, a short film produced by Proceedings of the National Academy of Sciences with support from the Pulitzer Center, addresses one of the most pressing issues of our time: the quest to stem the swelling tide of misinformation.

Decoding Deception explores potential remedies to this growing societal problem. While social media acts as an accelerant for the rampant spread of misinformation on climate change, public health, and politics, the rise of generative AI risks worsening the problem. Left unchecked, disinformation and misinformation can inflict lasting damage on people, institutions, and society writ large.

Growing interest from a group of interdisciplinary researchers has led to numerous efforts to dissect the problem and seek solutions. Decoding Deception follows researchers at the forefront of such efforts as they attempt to unravel the nature of the infodemic and uncover ways to contain it. Their work has yielded some promising early results, but no easy fixes. In the end, an approach borrowed from the field of public health—one that aims to mitigate threats and quash outbreaks before they spread—might offer the greatest chance of success.

Film trailer:
https://youtu.be/E6SqsREJhgw

The complete film can be freely accessed here:
https://www.pnas.org/post/multimedia/combating-misinformation

MEDIA CONTACT: Gene Russo, PNAS, Washington, DC; tel: 202-334-2699; email: erusso@nas.edu

For rights and permissions, please contact Gene Russo, the film’s co-director and PNAS Front Matter Editor.

About PNAS

PNAS is one of the world's most-cited multidisciplinary scientific journals. It covers the biological, physical, and social sciences and mathematics and publishes cutting-edge Research Reports, Commentaries, Perspectives, Colloquium Papers, and actions of the Academy. PNAS publishes daily online and in weekly issues.

For more information about PNAS or the NAS, visit www.pnas.org or www.nasonline.org

---

Article Title

Decoding Deception

 

In greening Arctic, caribou and muskoxen play key role

Study highlights importance of large grazing wildlife to Arctic ecosystem

University of California - Davis

 

image: 

A group of muskoxen gather on the Arctic tundra near Kangerlussuaq, Greenland.

view more 

Credit: Jeff Kerby

The story of Arctic greening has overlooked some main characters. At center stage are climate change and warming temperatures. Meanwhile, large grazing wildlife, such as caribou and muskoxen, also play a key role in the timing and abundance of Arctic plants, according to a study from the University of California, Davis.

The study, published today in the journal PNAS Nexus, highlights the importance of large herbivores to the Arctic ecosystem, linking grazing with plant phenology and abundance in the Arctic tundra.

Phenology is the study of the timing and cyclical patterns in nature, such as when birds migrate, or when a plant first sprouts or blooms. Understanding such patterns is critically important in the Arctic, which is warming faster than anywhere on Earth.

“Caribou and muskoxen play a key role in how soon plants emerge and this translates to how abundant they become,” said lead author Eric Post, a professor and arctic ecologist in the UC Davis Department of Wildlife, Fish and Conservation Biology. “This is an important, and overlooked, factor we need to consider as we seek to more fully understand climate change impacts on tundra vegetation in the Arctic.”

Exclusion experiment

The research was conducted at a long-term study site near Kangerlussuaq, Greenland, where Post has been studying plant and animal interactions for 22 years. To understand how herbivores affect the timing of plant growth and abundance, the scientists excluded caribou and muskoxen from some study areas. From 2009 to 2017, they compared the timing of spring green-up of nine plant species with and without the grazing animals. 

In general, plants where caribou or muskoxen were present experienced earlier green-up and greater abundance later in the growing season. About two-thirds of plants greened up earlier, and three-quarters were more abundant later in the season compared to plots without grazing. These include arctic draba and gray willow.

Some species, including dwarf birch and harebell, emerged later with grazers present.  Dwarf birch was the only species studied that did not increase in abundance under grazing. In all cases, the presence or absence of large grazing wildlife influenced how the plants responded.

Grazing awareness

Post said it is not yet clear why the plants respond in this way, but it is important to understand that there is a connection. 

“We’re used to thinking of the timing of plant availability as impacting the productivity of grazing animals, but not the reverse,” Post said. “The absence or presence of herbivores can also impact the timing of plant growth and their productivity.”

This is especially important considering that many caribou populations in the Arctic are in decline. Migratory tundra caribou (Rangifer tarandus) are listed as vulnerable by the IUCN Red List and have lost more than half of their total abundance since the 1990s.

A separate study coauthored by Post and published Nov. 7, noted that supporting sustainable populations of herbivores in the Arctic could be a more effective nature-based solution to climate change in the region than planting trees there.

Co-authors for the PNAS Nexus study include UC Davis alum Conor Higgins of the Yolo County Resource Conservation District, Pernille Bøving of UC Davis, Christian John of UC Santa Barbara, Mason Post of the University of Washington, and Jeffrey Kerby of the Scott Polar Research Institute at Cambridge University. The authors give special thanks to the late Mads Forchhammer for his critical input and inspiring the study. 

The study was funded by the U.S. National Science Foundation, National Geographic Society, European Union’s Horizon 2020 research program, and Aarhus University Research Foundation.

A caribou grazes grass and flowers in Greenland.

Credit

Eric Post, UC Davis)

---

Journal

PNAS Nexus

DOI

10.1093/PNASNEXUS-2024-00279RR 

Method of Research

Experimental study

Article Title

Large herbivores link plant phenology and abundance in arctic tundra

Article Publication Date

12-Nov-2024

Article Publication Date

12-Nov-2024

Plant green-up and herbivory in Greenland

PNAS Nexus

 

image: 

Male muskoxen near Kangerlussuaq, Greenland

view more 

Credit: Eric Post

A study links herbivory to phenology in the Arctic. Phenology is the study of the timing of events in the natural world. In recent decades, researchers have investigated how climate change is shifting many natural events. Eric Post and colleagues wanted to understand how a different variable—the presence or absence of herbivores—affects the timing of spring plant growth, or green-up, in Greenland. In an experiment lasting nine years, the authors excluded musk oxen and caribou from some areas, then compared the timing of the spring green-up of 9 tundra plant species in the areas with and without herbivores. Of the plants that showed altered green-up between the conditions, about two-thirds showed earlier green-up in plots with grazing than in plots without, including Draba nivalis, yellow arctic draba, and Salix glauca, gray willow. A few plants, including Betula nana, the dwarf birch, and Campanula Gieseckiana, harebell, showed later green-up under herbivory than under herbivore exclusion.  The team also measured plant abundance. Of the plants that showed a response to grazing, 75% were more abundant in the plots with herbivores. In general, early green-up under herbivory led to high abundance later in the growing season. The only plant that did not see increased abundance in plots with herbivores as compared to plots without herbivores was dwarf birch, which was also the most common species on the study plots. According to the authors, herbivory that reduced birch cover likely also reduced shade on other species, hastening and boosting their growth.

Arctic harebell near Kangerlussuaq, Greenland

Male caribou near Kangerlussuaq, Greenland.

Female muskoxen and calves near Kangerlussuaq, Greenlan

Credit

Eric Post

Journal

PNAS Nexus

Article Title

Large herbivores link plant phenology and abundance in Arctic tundra

 

Climate change threatens rare temperate rainforests

University of Leeds

Up to two thirds of the world’s temperate rainforests could fall victim to climate change by the year 2100 according to a new study by researchers at the University of Leeds.

In the first ever worldwide assessment of the impacts of global overheating on these rare ecosystems, scientists used maps of tree cover, forest condition, and climate data to assess how much of the world’s temperate rainforests have already been impacted by human activity and how climate change would push some regions to the brink.

The results of their study which are published today (Tuesday 12 November) in the journal Earth’s Future show that under the most pessimistic scenario, 68% of the world’s temperate rainforest, and in some regions 90%, would be lost over the next few decades. Under current commitments to reduce fossil fuel emissions, 23% of the world’s temperate rainforests will be lost. However, rapid action to halt fossil fuel emissions would reduce this loss to 9%, highlighting the urgent need to avert climate change.

Temperate rainforests are restricted to areas with cool and moist climates. Countries which have temperate rainforests include Canada, USA, Chile, Japan, Australia, New Zealand, and the UK.

Despite covering less than 1% of the Earth's land surface, they are recognized for their global ecological importance and carbon storage properties with intact temperate rainforests having higher carbon density than forests in other latitudes.

Ben Silver, a Research Fellow from Leeds’ School of Earth and Environment led the study. He said: “Unmitigated climate change is a disaster for temperate rainforest in the UK and globally, as they cannot survive the kinds of high summer temperatures which we are starting to observe more regularly and are only predicted to worsen in future climate change simulations.

“Our study also shows that if we work hard to slow climate change it is not too late to save the world’s temperate rainforests.

We hope our study will support the conservation of temperate rainforests by identifying those areas that are the least or the most vulnerable to climate change, and where there is potential to restore forest.”

Britain’s rainforests

In the UK temperate rainforest are found along the UK's western seaboard, including the West coast of Scotland, North and West Wales, Devon, Cornwall, Cumbria, and parts of Northern Ireland.

The Woodland Trust, which recognises temperate rainforests as a key conservation and restoration priority, describes them as one of the most biodiverse habitats, with the high humidity and low temperature range creating the perfect conditions for moisture-loving lichens and bryophytes (mosses and liverworts).

Temperate rainforests now cover less than 1% of land in Great Britain and last year governments in both Scotland and England announced plans to restore them.

The study concludes that the UK has more potential for restoration than anywhere else in the world as it hosts a quarter of the world’s unforested temperate rainforest climate zone. The study also found that UK rainforests are resilient to low and medium amounts of future warming.

Professor Dominick Spracklen, a co-author of the study said: “The UK could and should be a global leader in restoration of temperate rainforests. New funding and bold action by large landowners are urgently needed to help deliver government targets for temperate rainforest restoration.”

Dr Dominick A. DellaSala, Chief Scientist of the U.S group Wild Heritage, and one of the authors of the study, added: “All the world’s rainforests are the ‘lungs of the planet’ that must be protected and restored as natural climate solutions to avoid the worst of global overheating. Temperate rainforests need to take their place alongside tropical rainforests and the boreal forests of the north as strategically vital to a safe climate.”

Ends

Further information:

If using the images, please credit Simon Webb.

For media enquiries, please contact Kersti Mitchell in the University of Leeds press office via k.mitchell@leeds.co.uk

University of Leeds

The University of Leeds is one of the largest higher education institutions in the UK, with more than 40,000 students from more than 137 different countries. We are renowned globally for the quality of our teaching and research.

We are a values-driven university, and we harness our expertise in research and education to help shape a better future for humanity, working through collaboration to tackle inequalities, achieve societal impact and drive change. 

The University is a member of the Russell Group of research-intensive universities, and is a major partner in the Alan Turing, Rosalind Franklin and Royce Institutes www.leeds.ac.uk 

Follow University of Leeds or tag us into coverage: Twitter | Facebook | LinkedIn | Instagram

---

Journal

Earth's Future

DOI

10.1029/2024EF004812 

Method of Research

Computational simulation/modeling

Subject of Research

Not applicable

Article Title

Large Reductions in Temperate Rainforest Biome Due to Unmitigated Climate Change

Article Publication Date

12-Nov-2024

 

First amber find on the Antarctic continent

Southernmost discovery of amber allows new insights into Cretaceous forests near the South Pole

Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research

 

image: 

Macrograph of an approximately 70 µm amber extracted from the lignite in the sediments of the MeBo core PS104_20-2 9R.

view more 

Credit: Alfred Wegener Institute / V. Schumacher

Joint press release: Alfred Wegener Institute and TU Bergakademie Freiberg

Roughly 90 million years ago, climatic conditions in Antarctica were suitable for resin-producing trees. A team of researchers led by the Alfred Wegener Institute and the TU Bergakademie Freiberg have just released a paper in the journal Antarctic Science, in which they describe the southernmost discovery of amber in the world.

Until recently, a gap existed in the world map of amber discoveries: the Antarctic continent. But that gap has finally been closed, thanks to a team led by Dr Johann P. Klages from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research and Dr Henny Gerschel from the TU Bergakademie Freiberg. In a recently released paper, the experts describe the amber they discovered in a sediment core they had recovered on an expedition with the research icebreaker Polarstern in 2017, using the seafloor drill rig MARUM-MeBo70 at a water depth of 946 metres. They have named the discovery “Pine Island amber” after its locality in the Pine Island Bay of the Amundsen Sea Embayment – at 73.57° South, 107.09° West, to be precise.

“The analysed amber fragments allow direct insights into environmental conditions that prevailed in West Antarctica 90 million years ago,” says first author Johann P. Klages. “This fascinating find also indicates in more detail how the forest we reconstructed in our Nature study from 2020 could have functioned,” the AWI marine geologist adds. “It was very exciting to realise that, at some point in their history, all seven continents had climatic conditions allowing resin-producing trees to survive. Our goal now is to learn more about the forest ecosystem – if it burned down, if we can find traces of life included in the amber. This discovery allows a journey to the past in yet another more direct way.”

Those expecting large clumps of amber have to be disappointed: For analyses with reflected-light and fluorescence microscopy, the source material had to be air-dried and carefully sliced up into roughly fragments with 1 mm diameter from which the amber pieces were picked. But nevertheless, exciting structures were to be found: “The Antarctic amber likely contains remains of original tree bark as micro-inclusions. Considering its solid, transparent and translucent particles, the amber is of high quality, indicating its burial near the surface, as amber would dissipate under increasing thermal stress and burial depth,” explains Henny Gerschel, until recently a member of staff at the TU Bergakademie Freiberg and now a consultant at the Saxon State Office for the Environment, Agriculture and Geology.The team also found indications for pathological resin flow – a strategy trees use to seal damaged bark induced by parasites or wildfires, hence creating a chemical and physical barrier protecting from insect attacks and infections. “Our discovery is another piece of the puzzle and will help us gaining a better understanding of the swampy, conifer-rich, temperate rainforest environment identified near the South Pole during the mid-Cretaceous.”

---

Journal

Antarctic Science

DOI

10.1017/S0954102024000208 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

First discovery of Antarctic amber

Article Publication Date

12-Nov-2024

 

Using personal care products during and after pregnancy can increase exposure to toxic chemicals

An analysis by Brown University researchers found an association between the use of personal care products and concentrations of PFAS in people who were pregnant or lactating

Brown University

PROVIDENCE, R.I. [Brown University] — For people who are pregnant or nursing, more use of personal care products is associated with higher detectable levels of synthetic chemicals known to have adverse health effects, a new study by Brown University researchers found.

The study, published in Environment International, found that using personal care products like nail polish, makeup and hair dye while pregnant or lactating is associated with significantly higher levels of per- and polyfluoroalkyl substances, known as PFAS, in blood plasma and breast milk.

“While PFAS are ubiquitous in the environment, our study indicates that personal care products are a modifiable source of PFAS,” said study author Amber Hall, a postdoctoral research associate in epidemiology at the Brown University School of Public Health. “People who are concerned about their level of exposure to these chemicals during pregnancy or while breastfeeding may benefit from cutting back on personal care products during those times.”

PFAS are synthetic chemicals that have been used in consumer products and industrial settings since the 1950s due to their ability to resist oil, water and heat. The study notes that PFAS have been associated with a range of adverse health effects, including liver disease, cardiometabolic and cardiovascular issues, and various cancers.

While several studies have detected these chemicals in personal care products directly, few have evaluated whether using these products impacts internal PFAS concentrations, Hall said. This is important, she added, because exposure to PFAS during pregnancy could contribute to  adverse birth outcomes such as decreased birth weight, preterm birth, some neurodevelopmental disorders and diminished vaccine response in children.

Hall led a research team that analyzed data from the Maternal-Infant Research on Environmental Chemicals Study, which enrolled 2,001 pregnant people from 10 cities across Canada between 2008 and 2011. The researchers evaluated the contribution of the use of personal care products on PFAS concentrations in prenatal plasma (six to 13 weeks gestation) and human milk (two to 10 weeks postpartum). Participants reported frequency of use across eight product categories during the first and third pregnancy trimesters, one to two days postpartum, and two to 10 weeks postpartum.

In first-trimester pregnant people, the researchers found that higher use of nail care products, fragrances, makeup, hair dyes and hair sprays or gels was associated with higher plasma PFAS concentrations. Similar results were observed for third-trimester personal care product use and breast-milk PFAS concentrations at two to 10 weeks postpartum. 

For instance, participants who wore makeup daily in the first and third trimesters had 14% and 17% higher plasma and breast-milk PFAS concentrations, respectively, compared to people who did not wear makeup every day. In addition, the researchers found that people using colored-permanent dye one to two days postpartum had higher PFAS levels (16% to 18% increases compared to never using them) in human milk concentrations.

Hall noted that the study examined only four types of PFAS among thousands that are used in industry and commerce. Thus, the study likely underestimated the extent of exposure to all PFAS from these products during pregnancy, she said.

Hall conducted the research with Joseph Braun, a professor of epidemiology and director of children's environmental health at Brown University, who has been studying the health effects of PFAS for over a decade. Braun suggested that future studies examining how the use of personal care products affects PFAS exposure should consider differences by product type, as well as timing and frequency of use, or product formulation. This type of research can guide individual choices and also inform PFAS regulation, he said.

“Not only do studies like these help people assess how their product choices may affect their personal risk, but they can also help us show how these products could have population-level effects,” Braun said. “And that makes the case for product regulation and government action, so that we can remove some of the burden from individuals.”

The Maternal-Infant Research on Environmental Chemicals Study, which Braun helped to conduct, was supported by Health Canada’s Chemicals Management Plan, the Canadian Institutes of Health Research (MOP-81285) and the Ontario Ministry of the Environment.

---

Journal

Environment International

DOI

10.1016/j.envint.2024.109094 

Method of Research

Data/statistical analysis

Subject of Research

People

Article Title

Personal care product use and per- and polyfluoroalkyl substances in pregnant and lactating people in the Maternal-Infant Research on Environmental Chemicals study

COI Statement

Dr. Joseph Braun was compensated for serving as an expert witness on behalf of plaintiffs in litigation related to PFAS-contaminated drinking water. No other authors have any conflicts of interest to disclose.

 

Location of the world’s oldest ochre mine detected

University of Cologne

 

image: 

Ochre mine in the Lion Cavern in Eswatini, a country in southern Africa

view more 

Credit: Jörg Linstädter

In a recent study, an international team of researchers used luminescence dating and geochemical analyses to confirm the location of the oldest ochre mine in the world. It is located in the Lion Cavern in Eswatini, a country in southern Africa. Not only have the researchers dated the mine to an age of around 48,000 years, but they were also able to show how the ochre spread from the mine to nearby areas. The researchers analysed 173 samples from 15 Stone Age sites and reconstructed the methods of ochre extraction, use and transport networks. The study ‘Ochre communities of practice in Stone Age Eswatini’ was published in Nature Communications.

Ochre is a naturally occurring pigment made from iron-rich materials. It has been used by people for thousands of years – for cave paintings and to decorate symbolic objects and personal ornaments. Ochre has cultural, historical and spiritual significance in many societies and therefore offers researchers valuable insights into the growth of human society and human self-expression.

For this study, the researchers created a geochemical fingerprint of the ochre from the Lion Cavern region. For this purpose, small samples of ochre artefacts are safely made radioactive by neutron irradiation. Some of the resulting products can be radioactive. When these radioactive materials begin to decay, they emit characteristic energies. These can be measured and can thus provide information on where the material comes from and how it was created. In this way, the origin and transport routes of the artefacts can be reconstructed. In addition to this method, the researchers used an advanced laser technology, which makes the sample’s molecular bonds vibrate. This vibration indicates the mineral composition of the ochre. 

Dr Svenja Riedesel from the Cologne Luminescence Laboratory at the University of Cologne’s Institute of Geography contributed to the dating of the samples. Luminescence dating is based on the fact that materials such as quartz or feldspar absorb small amounts of energy from their surroundings over the course of time. The main source of this energy is the natural radiation in the ground, which is all around us. Small defects in the crystal structure of the material store this energy. “To determine the age of a material, we take a sample and expose it to light or heat in the laboratory,” said Riedesel. “In this way, the stored energy is released again and a weak light – known as luminescence – is produced.” The amount of light released indicates how long the material has not been exposed to sunlight or heat.

Riedesel used quartz grains to date the materials inside of the now abandoned mining caves of Lion Cavern. The results of the luminescence samples show that the caves were created by mining at least 42,000 years ago. This confirms earlier geochronological findings suggesting that ochre was mined in the Lion Cavern 48,000 years ago. “With the help of Optically Stimulated Luminescence dating, we were able to prove that this is the oldest known ochre mine in the world,” summarized the geographer.

---

Journal

Nature Communications

DOI

10.1038/s41467-024-53050-6 

Article Title

Ochre communities of practice in Stone Age Eswatini