Wednesday, April 24, 2024

  

Decoding Avar society



Using ancient DNA and archaeological evidence to unravel the kinship, social practices and transformations of early medieval steppe groups in Europe



Peer-Reviewed Publication

MAX PLANCK INSTITUTE FOR EVOLUTIONARY ANTHROPOLOGY

Avar-period cemetary 

IMAGE: 

EXCAVATION WORKS CONDUCTED BY THE EÖTVÖS LORÁND UNIVERSITY AT THE AVAR-PERIOD (6TH-9TH CENTURY AD) CEMETERY OF RÁKÓCZIFALVA, HUNGARY, IN 2006.

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CREDIT: INSTITUTE OF ARCHAEOLOGICAL SCIENCES, EÖTVÖS LORÁND UNIVERSITY MÚZEUM, BUDAPEST, HUNGARY



The Avars, who had come from Eastern Central Asia, ruled much of Eastern Central Europe for a quarter millennium, from the 6th to the 9th century CE. They may be less known than their less successful predecessors, the Huns. Yet in their cemeteries, they left one of the richest archaeological heritages in European history, including around 100,000 graves that have so far been excavated. From Avar funeral customs, and from written reports of their neighbours, scholars have reconstructed some of their social practices and ways of life. Yet now, archaeogenetics offer a totally new viewpoint on Avar communities who lived more than 1000 years ago. We can now analyse the ways in which individuals were related to each other up to the sixth to tenth degree. 

By combining newly generated ancient DNA data with complementary archaeological, anthropological and historical information, a team of the multidisciplinary Synergy Grant research project HistoGenes funded by the European Research Council (ERC) has thus opened new ways to find out more about kinship patterns, social practices and population development in the distant past. The team includes researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, together with Hungarian, Austrian and US research groups. In their collaboration, they set new standards by using all available methods, including the most advanced genetic and bio-informatic tools.

Studying whole communities

The historical knowledge on the Avar period populations was passed on to us by their enemies, mainly the Byzantines and the Franks, so we lack information on the internal organisation of their clans. Women are particularly underrepresented in historical sources, with only three incidental mentions, so knowledge of their lives is practically non-existent. We know that some groups came to Europe from the East Asian and Pontic steppes, but to what extent, if at all, were steppe traditions maintained in Avar society if at all? How did the newcomer groups from the East interact with each other and with the population of their new homeland in Europe? In essence, how did their way of life change over time in a completely new environment after they left the steppes and abandoned their nomadic way of life?

The study was carried out as part of the ERC Synergy Grant project HistoGenes (No. 856453), by a multidisciplinary research team of geneticists, archaeologists, anthropologists and historians, including researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, the Institute of Archaeological Sciences and Department of Biological Anthropology at Eötvös Loránd University (ELTE), Institute of Archaeogenomics, HUN-REN Research Centre for the Humanities, Budapest, Hungary, the Curt Engelhorn Center for Archaeometry in Mannheim, Germany, the Institute for Austrian Historical Research of the University of Vienna, Austria, the Institute for Advanced Study in Princeton, USA, and others. Contrary to common practice in ancient DNA research, the team aimed to study whole communities and therefore focused on sampling all available human remains from four fully excavated Avar period cemeteries. Thanks to exceptional aDNA preservation, they were able to analyse a total of 424 individuals and discovered that around 300 had a close (1st and 2nd degree) relative buried in the same cemetery. This allowed the reconstruction of several extensive pedigrees, the largest of which is nine generations deep and spans about 250 years.

Community dynamics

The researchers were able to identify communities that practised a strict patrilineal descent system, where patrilocality (male individuals staying in the community after marriage) and female exogamy (female individuals moving to their partner’s community after marriage) were the norm. Communities were locally centred around a main patriline, were related to each other through the systematic practice of female exogamy. Zuzana Hofmanová, senior author of the study says: “In a way, this pattern shows the role of females in promoting the cohesion of this society, it was the role of females that connected the individual communities”. Multiple reproductive partners were common. Several independent cases show that these communities practised so-called levirate unions. This practice involves related male individuals (siblings or father and son) having offspring with the same female individual. Guido Alberto Gnecchi-Ruscone, first author of the study, adds: ”These practices, together with the absence of genetic consanguinity, indicate that the society maintained a detailed memory of its ancestry and knew who its biological relatives were  over generations”.

These social practices are consistent with evidence from historical sources and anthropological research on Eurasian Steppe societies. Thanks to the high resolution provided by the extensive pedigrees and whole-cemetery data, the researchers were also able to identify a clear temporal transition within one of the sites analysed. This was revealed by the shift from one patriline to another and by changes in patterns of distant relatedness (the network of genetic relatedness, i.e. the IBD-network). Zsófia Rácz, co-first author of the study, says: “This community replacement reflects both an archaeological and dietary shift that we discovered within the site itself, but also a large-scale archaeological transition that occurred throughout the Carpathian Basin”. This change, probably related to political changes in the region, was not accompanied by a change in ancestry and would therefore have been invisible without the study of whole communities. This finding highlights how genetic continuity at the level of ancestry can still conceal replacements of whole communities, and has important implications for future studies comparing genetic ancestry and archaeological shifts.


Burial with a horse at the Rákóczifalva site, Hungary (8th century AD). This male individual, who died at a young age, belongs to the 2nd generation of pedigree 4, and was one of the sons of the founder of this kinship unit.

CREDIT

Institute of Archaeological Sciences, Eötvös Loránd University Múzeum, Budapest, Hungary

Gold figurine from the excavation at Rákóczifalva, Hungary. Metal detector find from the territory of the Avar cemetery (7th century AD).

CREDIT

Institute of Archaeological Sciences, Eötvös Loránd University Múzeum, Budapest, Hungary

This research project has been funded by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 856453 ERC-2019-SyG HistoGenes). HistoGenes is a research framework investigating the period of 400 to 900 CE in the Carpathian Basin from an interdisciplinary perspective.

Study reveals social organization of Avar realm



INSTITUTE FOR ADVANCED STUDY
Interconnected Pedigrees 

IMAGE: 

THE LARGEST SET OF INTERCONNECTED PEDIGREES RECONSTRUCTED IN RÁKÓCZIFALVA (RK) AND THE CEMETERY MAP HIGHLIGHTING THE BURIAL LOCATION OF THE RELATED INDIVIDUALS: A) A LARGE (146 INDIVIDUALS) INTERCONNECTED SET OF SUB-PEDIGREES, NUMBER 1 TO 5 AND FOUR SMALLER PEDIGREES (34 INDIVIDUALS), NUMBER 6, 7, 8 AND 12. LEVIRATE UNIONS ARE REPORTED WITH COLORED LINES CONNECTING THE PARTNERS INVOLVED. THE MALES’ Y-HAPLOGROUPS ARE VISUALIZED WITH COLORED BORDERS AROUND THE INDIVIDUALS. BLACK SYMBOLS CORRESPOND TO THE INDIVIDUALS WE HAVE ADNA FROM, WHITE ONES ARE THE MISSING INDIVIDUALS INFERRED ON THE BASIS OF AVAILABLE DATA. ON THE LEFT A COLORED BAR REPRESENTS THE TIMELINE SPANNING THE WHOLE AVAR PERIOD COVERING THE 9+ GENERATIONS OF THE PEDIGREES. B) CEMETERY MAP OF RÁKÓCZIFALVA 8 (THE SMALLER PART ON THE RIGHT SEPARATED BY 95 METERS) AND 8A (THE LEFT PART) COLOR CODED ACCORDING TO THE PEDIGREE NUMBERED AS IN A.

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CREDIT: HISTOGENES





A multidisciplinary research team including Patrick Geary, Professor Emeritus in the School of Historical Studies at the Institute for Advanced Study, together with Hungarian, Austrian, and German research groups, has combined ancient DNA data with a clear archaeological, anthropological, and historical context to reconstruct the social dynamics of Avar-period steppe descent populations that settled in Europe's Carpathian Basin in the 6th century.

Their research findings were published today in Nature.

The Avars, who had come from Eastern Central Asia, ruled much of Eastern Central Europe for a quarter millennium, from the 6th to the 9th century C.E. They may be less known than their less successful predecessors, the Huns. Yet in their cemeteries, they left one of the richest archaeological heritages in European history, including around 100,000 graves that have so far been excavated. From Avar funeral customs, and from written reports of their neighbors, scholars have reconstructed some of their social practices and ways of life. Yet now, archaeogenetics offers a totally new viewpoint on Avar communities who lived more than 1,000 years ago. We can now analyze the ways in which individuals were related to each other up to the sixth to tenth degree.

The historical knowledge on the Avar period populations was passed on by their enemies, mainly the Byzantines and the Franks, so information is lacking on the internal organization of their clans. Women are particularly underrepresented in historical sources, with only three incidental mentions, so knowledge of their lives is practically non-existent. It is known that some groups came to Europe from the East Asian and Pontic steppes, but to what extent were steppe traditions maintained in Avar society, if at all? How did the newcomer groups from the East interact with each other and with the population of their new homeland in Europe? In essence, how did their way of life change over time in a completely new environment after they left the steppes and abandoned their nomadic way of life?

Studying whole communities
Contrary to common practice in ancient DNA research, the team aimed to study whole communities and therefore focused on sampling all available human remains from four fully excavated Avar period cemeteries, analyzing entire communities by sampling all available human remains from four fully excavated Avar-era cemeteries, analyzing a total of 424 individuals and discovering that around 300 had a close (1st and 2nd degree) relative buried in the same cemetery. This allowed the reconstruction of several extensive pedigrees—the largest of which is nine generations deep and spans about 250 years—revealing that the communities practiced a strict patrilineal system of descent. Women played a key role in promoting social cohesion, linking individual communities by marrying outside their original community. Changes within a site indicated community replacement, probably linked to political changes, that remained genetically invisible, showing that genetic continuity at the level of ancestry can mask the replacement of whole communities, with important implications for future archaeological and genetic research.

The study was carried out by a multidisciplinary research team of geneticists, archaeologists, anthropologists, and historians, including researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany; the Institute of Archaeological Sciences, Eötvös Loránd University, Budapest, Hungary; the Curt Engelhorn Center for Archaeometry in Mannheim, Germany; and the Institute for Austrian Historical Research of the University of Vienna, Austria; as well as the Institute for Advanced Study.

Community dynamics
The researchers were able to identify communities that practiced a strict patrilineal descent system, where patrilocality (male individuals staying in the community after marriage) and female exogamy (female individuals moving to their partner’s community after marriage) were the norm. Communities were locally centered around a main patriline and were related to each other through the systematic practice of female exogamy. Zuzana Hofmanová, senior author of the study, says, "In a way, this pattern shows the role of females in promoting the cohesion of this society, it was the role of females that connected the individual communities." Multiple reproductive partners were common. Several independent cases show that these communities practiced so-called levirate unions. This practice involves related male individuals (siblings or father and son) having offspring with the same female individual. Guido Alberto Gnecchi-Ruscone, first author of the study, adds, "These practices, together with the absence of genetic consanguinity, indicate that the society maintained a detailed memory of its ancestry and knew who its biological relatives were over generations." These social practices are consistent with evidence from historical sources and anthropological research on Eurasian Steppe societies. Thanks to the high resolution provided by the extensive pedigrees and whole-cemetery data, the researchers were also able to identify a clear temporal transition within one of the sites analyzed. This was revealed by the shift from one patriline to another and by changes in patterns of distant relatedness (the network of genetic relatedness, i.e., the IBD-network). Zsófia Rácz, co-first author of the study, says, "This community replacement reflects both an archaeological and dietary shift that we discovered within the site itself, but also a large-scale archaeological transition that occurred throughout the Carpathian Basin." This change, probably related to political changes in the region, was not accompanied by a change in ancestry and would therefore have been invisible without the study of whole communities. This finding highlights how genetic continuity at the level of ancestry can still conceal replacements of whole communities, and has important implications for future studies comparing genetic ancestry and archaeological shifts. The team has thus opened new ways to find out more about kinship patterns, social practices, and population development in the distant past. In their collaboration, the team set new standards by using all available methods, including the most advanced genetic and bio-informatic tools.

"This study, which is one in the series of innovative publications from the HistoGenes project, demonstrates how new, fundamental insights into past societies can be gained when historians, archaeologists, anthropologists, and geneticists collaborate as equals," said Geary.

This research project has been funded by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant Agreement No. 856453 ERC-2019-SyG HistoGenes). HistoGenes is a research framework investigating the period of 400 to 900 C.E. in the Carpathian Basin from an interdisciplinary perspective.

About the Institute
The Institute for Advanced Study has served as one of the leading independent centers for theoretical research and intellectual inquiry since its establishment in 1930, advancing the frontiers of knowledge across the sciences and humanities. From founding IAS Faculty Albert Einstein, Erwin Panofsky, and John von Neumann to influential figures Emmy Noether, George Kennan, and J. Robert Oppenheimer to the foremost thinkers of the present, IAS is dedicated to enabling independent inquiry and fundamental discovery.

Each year, the Institute welcomes more than 250 of the world’s most promising post-doctoral researchers and scholars who are selected and mentored by a permanent Faculty, each of whom are preeminent leaders in their fields. Among present and past Faculty and Members, there have been 35 Nobel Laureates, 44 of the 62 Fields Medalists, and 23 of the 27 Abel Prize Laureates, as well as winners of the Pulitzer Prize in History; the Wolf, Holberg, and Kluge prizes; and many MacArthur and Guggenheim fellows, among other honors.


Network analysis of the haplotype-IBD sharing between the Avar period individuals analyzed in the study: a) Visualization of the network of IBD connections (edges) between the ancient individuals (nodes) colored according to their site with squares representing males and circles females. The males’ Y-haplogroups are visualized with colored borders around the individuals. The strength of the IBD connection is summarized by the maximum IBD length in centi-Morgan found for each pair of individuals. The distribution of these lengths from the lowest (>12 cM cutoff) to the highest (>280 cM for first degree relatives) is reflected in the width and the color scale of each edge. b) the only adults network considering only males (top) and only females (bottom). c) Network statistics calculated on the adults-only network. On the left the degree centrality, k (defined as the number of links held by the node) is plotted vs the cumulative density function of the degrees distribution. On the right, the total k is plotted vs the ratio of k calculated between-site edges and total k (kB/k).

CREDIT

HistoGenes

Making diamonds at ambient pressure


Scientists develop novel liquid metal alloy system to synthesize diamond under moderate conditions


Peer-Reviewed Publication

INSTITUTE FOR BASIC SCIENCE

Figure 1 

IMAGE: 

GROWTH OF DIAMOND IN LIQUID METAL ALLOY UNDER 1 ATMOSPHERE PRESSURE. (A) A PHOTO SHOWING THE AS-GROWN DIAMOND ON THE SOLIDIFIED LIQUID METAL SURFACE. (B) AN OPTICAL IMAGE OF THE AS-GROWN CONTINUOUS DIAMOND FILM ON THE SOLIDIFIED LIQUID METAL SURFACE. (C) AN OPTICAL IMAGE OF THE AS-TRANSFERRED DIAMOND FILM ON A QUANTIFOIL HOLEY AMORPHOUS CARBON FILM COATED CU TEM GRID. (D) AN ATOMIC FORCE MICROSCOPY TOPOGRAPHIC IMAGE OF THE AS-TRANSFERRED DIAMOND FILM ON THE CU TEM GRID. (E) A CROSS-SECTION TEM IMAGE OF AN AS-GROWN SINGLE DIAMOND PARTICLE ON THE SOLIDIFIED LIQUID METAL SURFACE. (F) AN ATOMIC RESOLUTION TEM IMAGE OF THE AS-GROWN DIAMOND. (G) A SCANNING ELECTRON MICROSCOPY IMAGE SHOWING A GROWN DIAMOND (PARTIALLY) SUBMERGED IN THE SOLIDIFIED LIQUID METAL. (H) SCHEME SHOWING THE DIFFUSION OF CARBON THAT LEADS TO THE GROWTH OF DIAMOND AT THE BOTTOM SURFACE OF THE LIQUID METAL.

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CREDIT: INSTITUTE FOR BASIC SCIENCE




Did you know that 99% of synthetic diamonds are currently produced using high-pressure and high-temperature (HPHT) methods?[2] A prevailing paradigm is that diamonds can only be grown using liquid metal catalysts in the gigapascal pressure range (typically 5-6 GPa, where 1 GPa is about 10,000 atm), and typically within the temperature range of 1300-1600 °C. However, the diamonds produced using HPHT are always limited to sizes of approximately one cubic centimeter due to the components involved. That is—achieving such high pressures can only be done at a relatively small length scale. Discovering alternative methods to make diamonds in liquid metal under milder conditions (particularly at lower pressure) is an intriguing basic science challenge that if achieved could revolutionize diamond manufacturing. Could the prevailing paradigm be challenged?

A team of researchers led by Director Rod RUOFF at the Center for Multidimensional Carbon Materials (CMCM) within the Institute for Basic Science (IBS), including graduate students at the Ulsan National Institute of Science and Technology (UNIST), have grown diamonds under conditions of 1 atmosphere pressure and at 1025 °C using a liquid metal alloy composed of gallium, iron, nickel, and silicon, thus breaking the existing paradigm. The discovery of this new growth method opens many possibilities for further basic science studies and for scaling up the growth of diamonds in new ways.

Director Ruoff, who is also a UNIST Distinguished Professor notes, “This pioneering breakthrough was the result of human ingenuity, unremitting efforts, and the concerted cooperation of many collaborators.” Researchers led by Ruoff conducted a series of experiments, involving several hundred parameter adjustments and a variety of experimental approaches before they finally succeeded in growing diamonds using a ‘home-built’ cold-wall vacuum system.

Ruoff notes “We had been running our parametric studies in a large chamber (named RSR-A with an interior volume of 100 liters) and our search for parameters that would yield growth of diamond was slowed due to the time needed to pump out air (about 3 minutes), purge with inert gas (90 minutes), followed by pumping down again to vacuum level (3 minutes) so that the chamber could then be filled with 1 atmosphere pressure of quite pure hydrogen/methane mixture (again 90 minutes); that is over 3 hours before the experiment could be started! I asked Dr. Won Kyung SEONG to design & build a much smaller chamber to greatly reduce the time needed to start (and finish!) the experiment with the liquid metal exposed to the mixture of methane and hydrogen.” Seong adds, “Our new homebuilt system (named RSR-S, with an interior volume of only 9 liters) can be pumped out, purged, pumped out, and filled with methane/hydrogen mixture, in a total time of 15 minutes. Parametric studies were greatly accelerated, and this helped us discover the parameters for which diamond grows in the liquid metal!”

The team discovered that diamond grows in the sub-surface of a liquid metal alloy consisting of a 77.75/11.00/11.00/0.25 mix (atomic percentages) of gallium/nickel/iron/silicon when exposed to methane and hydrogen under 1 atm pressure at ~1025 °C.

Yan GONG, UNIST graduate student and first author, explains “One day with the RSR-S system when I ran the experiment and then cooled down the graphite crucible to solidify the liquid metal, and removed the solidified liquid metal piece, I noticed a ‘rainbow pattern’ spread over a few millimeters on the bottom surface of this piece. We found out that the rainbow colors were due to diamonds! This allowed us to to identify parameters that favored the reproducible growth of diamond.”

The initial formation occurs without the need for diamond or other seed particles commonly used in conventional HPHT and chemical vapor deposition synthesis methods. Once formed, the diamond particles merge to form a film, which can be easily detached and transferred to other substrates, for further studies and potential applications.

The synchrotron two-dimensional X-ray diffraction measurements confirmed that the synthesized diamond film has a very high purity of the diamond phase. Another intriguing aspect is the presence of silicon-vacancy color centers in the diamond structure, as an intense zero-phonon line at 738.5 nm in the photoluminescence spectrum excited by using a 532 nm laser was found.

Coauthor Dr. Meihui WANG notes, “This synthesized diamond with silicon-vacancy color centers may find applications in magnetic sensing and quantum computing.”

The research team delved deeply into possible mechanisms for diamonds to nucleate and grow under these new conditions. High-resolution transmission electron microscope (TEM) imaging on cross-sections of the samples showed about 30-40 nm thick amorphous subsurface region in the solidified liquid metal that was directly in contact with the diamonds. Coauthor Dr. Myeonggi CHOE notes, “Approximately 27 percent of atoms that were present at the top surface of this amorphous region were carbon atoms, with the carbon concentration decreasing with depth.”

Ruoff elaborates, “The presence of such a high concentration of carbon ‘dissolved’ in a gallium-rich alloy could be unexpected, as carbon is reported to be not soluble in gallium. This may explain why this region is amorphous—while all other regions of the solidified liquid metal are crystalline. This sub-surface region is where our diamonds nucleate and grow and we thus focused on it.”

Researchers exposed the Ga-Fe-Ni-Si liquid metal to the methane/hydrogen for short periods of time to try to understand the early growth stage—well prior to the formation of a continuous diamond film. They then analyzed the concentrations of carbon in the subsurface regions using time-of-flight secondary ion mass spectrometry depth profiling. After a 10-minute run, no diamond particles were evident but there were ~65 at% carbon atoms present in the region where the diamond typically grows. Diamond particles began to be found after a 15-minute run, and there was a lower subsurface C atom concentration of ~27 at%.

Ruoff explains, “The concentration of subsurface carbon atoms is so high at around 10 minutes that this time exposure is close to or at supersaturation, leading to the nucleation of diamonds either at 10 minutes or sometime between 10 and 15 minutes. The growth of diamond particles is expected to occur very rapidly after nucleation, at some time between about 10 minutes and 15 minutes.”

The temperature in 27 different locations in the liquid metal was measured with an attachment to the growth chamber having an array of nine thermocouples that was designed and built by Seong. The central region of the liquid metal was found to be at a lower temperature compared to the corners and sides of the chamber. It is thought that this temperature gradient is what drives carbon diffusion towards the central region, facilitating diamond growth.

The team also discovered that silicon plays a critical role in this new growth of diamond. The size of the grown diamonds becomes smaller and their density higher as the concentration of silicon in the alloy was increased from the optimal value. Diamonds could not be grown at all without the addition of silicon, which suggests that silicon may be involved in the initial nucleation of diamond.

This was supported by the various theoretical calculations conducted to uncover the factors that may be responsible for the growth of diamonds in this new liquid metal environment. Researchers found that silicon promotes the formation and stabilization of certain carbon clusters by predominantly forming sp3 bonds like carbon. It is thought that small carbon clusters containing Si atoms might serve as the ‘pre-nuclei’, which can then grow further to nucleate a diamond. It is predicted that the likely size range for an initial nucleus is around 20 to 50 C atoms.

Ruoff states, “Our discovery of nucleation and growth of diamond in this liquid metal is fascinating and offers many exciting opportunities for more basic science. We are now exploring when nucleation, and thus the rapid subsequent growth of diamond, happens. Also ‘temperature drop’ experiments where we first achieve supersaturation of carbon and other needed elements, followed by rapidly lowering the temperature to trigger nucleation— are some studies that seem promising to us.”

The team discovered their growth method offers significant flexibility in the composition of liquid metals. Researcher Dr. Da LUO remarks, “Our optimized growth was achieved using the gallium/nickel/iron/silicon liquid alloy. However, we also found that high-quality diamond can be grown by substituting nickel with cobalt or by replacing gallium with a gallium-indium mixture.”

Ruoff concludes, “Diamond might be grown in a wide variety of relatively low melting point liquid metal alloys such as containing one or more of indium, tin, lead, bismuth, gallium, and potentially antimony and tellurium—and including in the molten alloy other elements such as manganese, iron, nickel, cobalt and so on as catalysts, and others as dopants that yield color centers. And there is a wide range of carbon precursors available besides methane (various gases, and also solid carbons). New designs and methods for introducing carbon atoms and/or small carbon clusters into liquid metals for diamond growth will surely be important, and the creativity and technical ingenuity of the worldwide research community seem likely to me, based on our discovery, to rapidly lead to other related approaches and experimental configurations. There are numerous intriguing avenues to explore!”

This research was supported by the Institute for Basic Science and has been published in the journal Nature.


Diamonds of various morphologies as grown under different growth conditions. (a) Growth by using a liquid metal alloy of Ga/Ni/Fe/Si (77.75/11.00/11.00/0.25 at%) under methane/hydrogen (1/20 molar ratio). (b) Growth by using a liquid metal alloy of Ga/Ni/Fe/Si (77.50/11.00/11.00/0.50 at%) under methane/hydrogen (1/20 molar ratio). (c) Growth by using a liquid metal alloy of Ga/In/Ni/Fe/Si (38.88/38.87/7.33/14.67/0.25 at%) under methane/hydrogen (1/20 molar ratio). (d) Growth by using a liquid metal alloy of Ga/Ni/Fe/Si (77.75/11.00/11.00/0.25 at%) under methane/hydrogen (1/5 molar ratio).

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Institute for Basic Science

 

Modeling broader effects of wildfires in Siberia



HOKKAIDO UNIVERSITY
Estimated mortality and economic impacts of enhanced Siberian wildfires 

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ESTIMATED MORTALITY AND ECONOMIC IMPACTS OF ENHANCED SIBERIAN WILDFIRES THROUGH AIR POLLUTION FOR SELECTED EAST ASIAN COUNTRIES AND RUSSIAN ADMINISTRATIVE DISTRICTS UNDER THE PRESENT CLIMATE CONDITION WITH THE MOST EXTREME WILDFIRE SCENARIO ESTIMATED BY THE MODELING. (TEPPEI J. YASUNARI, ET AL. EARTH’S FUTURE. APRIL 24, 2024)

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CREDIT: TEPPEI J. YASUNARI, ET AL. EARTH’S FUTURE. APRIL 24, 2024





As wildfires in Siberia become more common, global climate modeling estimates significant impacts on climate, air quality, health, and economies in East Asia and across the northern hemisphere.

The global effects of increasing wildfires in Siberia have been modeled by researchers at Hokkaido University and colleagues at the University of Tokyo and Kyushu University. The results, published in the journal Earth’s Future, suggest significant and widespread effects on air quality, climate, health, and economics under the most extreme wildfire scenarios.

The authors performed global numerical simulation experiments to evaluate how the increased intensity of wildfires in Siberia would affect air quality, premature mortality, and economy through increased atmospheric aerosols (air pollution particles) under the present climate and near-future global warming scenarios.

“Our modeling reveals a cooling effect broadly across the northern hemisphere and worsened air quality in extensive downwind regions,” says Associate Professor Teppei Yasunari of the Hokkaido team.

A major impact of wildfires on the atmosphere is their emission of atmospheric aerosols—mixtures of tiny particles suspended in the air. These aerosols affect air quality and can have wide-ranging effects on climate.

This research focused on the Siberian wildfires using a Japanese global climate modeling system called the Model for Interdisciplinary Research on Climate version 5 (MIROC5), combined with other models, such as the aerosol model SPRINTARS. The analysis combined atmospheric effects with exploring coupled influences between the atmosphere and the oceans.

The simulated atmospheric cooling effect across broad areas throughout the northern hemisphere is likely linked to the reflection of sunlight from the aerosol particles. The research suggests this may induce a partial suppression of warming under the near-future global warming conditions near the Siberian wildfire areas.

Under the most extreme wildfire scenario, another significant impact will be worsened air quality due to particulate and gas (aerosol precursor) pollution emissions, not only in the local regions but also across large areas of East Asia that are generally downwind of the wildfires.

“Our results suggest that increased efforts are needed to limit the effects of the Siberian wildfires somehow to prevent excess deaths, respiratory and other illnesses, and economic losses because it is hard to prevent the occurrence of Siberian wildfires in such large areas,” Yasunari says.

The modeling suggests that the estimated direct impact of increased deaths due to air pollution could incur health-related costs in the order of 10 billion US dollars annually. However, this study did not consider substantial further costs and secondary social effects that could result from non-fatal illnesses, leading to workplace absences and reduced educational opportunities. Therefore, a greater level of costs may be possible in reality.

The surprisingly broad significance of wildfires in Siberia assessed by the global sensitivity simulations with the global climate model suggests that the model’s performance should be further refined to allow quantitatively improved estimated impacts that will assist efforts to understand and mitigate the effects.

“Our findings send a critical message about the broad effect of increased particulate matter due to massive wildfires in the atmosphere on climate and air quality, which will become ever more significant as the worldwide changes due to global warming proceed,” Yasunari concludes.

 

Hurricanes jeopardize carbon-storing New England forests


Study finds carbon-offset programs insufficiently account for future storm risks



DARTMOUTH COLLEGE

Dartmouth's Second College Grant 

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DARTMOUTH'S SECOND COLLEGE GRANT IN NORTHERN NEW HAMPSHIRE CONSISTS OF NEARLY 27,000 ACRES OF FORESTLAND.
 

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CREDIT: PHOTO BY ELI BURAKIAN '00 / DARTMOUTH.




As American companies and public policies strive to mitigate their carbon dioxide emissions, many are relying on carbon offsets to reduce their carbon footprint, especially those who have pledged to achieve "net-zero emissions."

Sequestering carbon in forests is an example of a nature-based solution that is being used to address climate change, but a new study suggests that hurricanes could pose a risk.

Offset programs involve investments organizations or individuals can make in projects that cut carbon emissions, such as solar energy, or that can store carbon, such as preserving and enhancing forests.

As it happens, New England is one of the most heavily forested regions in the U.S. with Maine at 83%, New Hampshire at 80%, and Vermont at 74%.

In the California carbon market, the largest regulatory U.S. carbon market, 3% of a carbon offset project is reserved for catastrophic risks such as hurricanes and other storm events.

Wildfires, which comprise their own separate risk category, can also deplete forests that store carbon, known as "carbon stocks," and have typically been the focus of prior research on disturbances to such stocks.

The study finds that a single hurricane may wipe out 5% to 10% of total aboveground forest carbon, through tree damage, in New England. The results are published in Global Change Biology.

"Our results reveal that carbon offset programs in the U.S. do not adequately account for the risk of hurricanes, as a single storm could wipe out everything the program has set aside to ensure against risk," says lead author Shersingh Joseph Tumber-Dávila, an assistant professor of environmental studies at Dartmouth and investigator at Harvard Forest where he conducted this work.

While New England hasn’t experienced many severe hurricanes in recent decades, they are an important driver of long-term ecosystem change. The Hurricane of 1938, for example, caused widespread tree damage in New England, leading to the salvaging of 500 million board feet of lumber in the Granite State alone, according to the Society for the Protection of New Hampshire Forests.

Hurricanes obtain their energy from the ocean and typically impact the southeastern coastal regions of the U.S.; however, they are a dominant disturbance agent in the Northeast as well.

"As the climate warms and sea surface temperatures continue to rise, hurricanes could get stronger and will have the capacity to stay on land longer, with the potential to move inland and northward into the heavily forested regions of the Northeast," says Tumber-Dávila.

For the study, the research team examined the 10 most powerful hurricanes that had an impact on land in New England over the past century, including Hurricane Bob in August 1991, and analyzed how the region's forests would be impacted if one of those storms were to hit today.

They mapped the trees—the aboveground forest carbon in New England—using USDA Forest Service Forest Inventory and Analysis Program data and mapped the hurricanes using tracking and wind speed data to simulate a storm's path and strength in a geographic area. They determined how susceptible a forest was to wind damage based on the height and type of the trees. The team applied meteorological predictions to estimate the potential future strength of hurricanes.

The study finds that a projected 8% and 16% increase in hurricane wind speeds leads to a nearly 11- and 25-fold increase in high-severity impacts that would likely cause widespread tree death.

"In the context of climate change mitigation, the forest sector is unique in that carbon moves both into and out of the system," says senior author Jonathan Thompson, a senior ecologist and research director at Harvard Forest, which is based in Petersham, Massachusetts. "When mitigation programs look to forests, they often focus only on carbon moving into the forest through sequestration but our research shows the potential for carbon to move back into the atmosphere via hurricanes."

To estimate how long it would take for the forest carbon to be emitted from the downed trees due to the given hurricane, the researchers took into account wood decay rates and estimated the timber products that could be made from the salvaged wood based on regional timber product reports.

The results show that it takes nearly 19 years for trees knocked over by a hurricane to become a net emission and 100 years for most of the downed carbon (90%) to be emitted.

One hurricane however, can lead to the release of the 10-year equivalent of carbon sequestered in New England's forests.

Tumber-Dávila says the study suggests that future hurricanes need to be considered as using New England forests to capture and store carbon from the atmosphere becomes more popular.

"If forest carbon stocks are going to continue to be used as a nature-based climate solution, we have to be critical about evaluating its longevity and risks, to make sure that we're doing something that actually has an impact," says Tumber-Dávila.

Tumber-Dávila is available for comment at: Joseph.Tumber-Davila@dartmouth.edu.

Dartmouth's Second College Grant in northern New Hampshire consists of nearly 27,000 acres of forestland.

CREDIT

Photo by Eli Burakian '00 / Dartmouth.