It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Tuesday, December 01, 2020
Biodiesel made from discarded cardboard boxes
Development of a microorganism that doubles the yield of biodiesel precursor production using genetic scissors and based on the principles of evolution; expected to reduce fine dust release and reduce greenhouse gas emissions
IMAGE: CONCEPTUAL DIAGRAM FOR PRODUCING BIOFUELS USING MICROORGANISMS AS RAW MATERIALS FOR WOOD-BASED BIOMASS view more
CREDIT: KOREA INSTITUE OF SCIENCE AND TECHNOLOGY(KIST)
Automobile exhaust emitted by fossil-fuel-based vehicles, especially those operating on diesel, is known to be a major source of fine dust and greenhouse gases . Using biodiesel instead of diesel is an effective way of coping with climate change caused by greenhouse gases while reducing fine dust emission. However, the current method of producing biodiesel by chemically processing vegetable oil or waste cooking oil-such as palm or soybean oil-is limited because of the unreliable availability of raw materials.
Therefore, there is an active effort to develop biofuels by converting lignocellulosic biomass generated as a by-product of farming or logging, instead of consuming raw materials derived from food crops. Lignocellulosic biomass is an economical and sustainable raw material that can be converted to eco-friendly motor fuel through microbial metabolism.
Dr. Sun-Mi Lee and her team at the Clean Energy Research Center of the Korea Institute of Science and Technology (KIST) have announced that they have developed a novel microorganism capable of producing biodiesel precursors from lignocellulosic biomass such as discarded agricultural by-products, waste paper, and cardboard boxes. This microorganism has achieved the product yield twice of what was obtainable from its predecessors.
This novel microorganism can produce biodiesel precursors during the process of metabolizing sugars contained in the lignocellulosic biomass that it feeds on. The sugar contained in lignocellulosic biomass is generally composed of 65-70% glucose and 30-35% xylose. While microorganisms that exist in nature are effective in producing diesel precursors by metabolizing glucose, they do not feed on xylose, thus limiting the yield of the raw materials.
To solve this problem, the KIST research team developed a new microorganism that can produce diesel precursors by effectively metabolizing xylose as well as glucose. In particular, the metabolic pathway of the microorganism was redesigned using genetic scissors to prevent interference with the supply of coenzymes essential for producing diesel precursors. The ability to metabolize xylose was improved by effectively controlling the process of evolution in a laboratory, for instance, by selecting and cultivating only those microorganisms that delivered excellent performance.
This confirmed the possibility of producing diesel precursors using all sugar components including xylose from lignocellulosic biomass, and the product yield was almost doubled, compared to that obtained in previous studies which employed metabolic pathways having unresolved coenzyme issues.
"Biodiesel is an effective alternative fuel that can reduce greenhouse gas and fine dust emissions without restricting the operation of existing diesel-fueled vehicles, and we developed a core technology that can improve the economic efficiency of biodiesel production," said Dr. Sun-Mi Lee of KIST. "At a time like this, when we feel climate change in our bones due to frequent typhoons and severe weather phenomena, expanded supply of biofuels that help us cope with climate change most quickly and effectively will facilitate the expansion of related industries and the development of technology."
CAPTION
Xyloxic metabolic pathways introduced in diesel raw material production strains
This study was carried out with a grant from the Ministry of Science and ICT (MSIT), as part of the Institutional R&D Program of KIST and the New and Renewable Energy Research Program of the Korea Energy Technology Evaluation and Planning, and it was published in the most recent edition of Global Change Biology Bioenergy (Top 0.55% in the field of JCR).
Tree rings provide evidence for climate regime shifts
Tree rings, with their special characteristics of precise dating, annual resolution, long time series and climate sensitivity, have been widely considered a useful proxy for past climate variations.
Researchers at the Institute of Botany of the Chinese Academy of Sciences have given an overview on using tree rings to identify climate regime shifts in a perspective paper entitled "Tree rings circle an abrupt shift in climate," which was published in Science on Nov. 26.
In the paper, Prof. ZHANG Qi-Bin and Dr. FANG Ouya provided background in the field and discussed its advances. They also referenced a paper reporting a recent climate regime shift to a hotter and drier climate over inner East Asia, which was written by lead author ZHANG Peng from South Korea and published in the same issue of Science.
"Careful attention is required when using tree rings to reconstruct a specific climate variable over a large geographical region," said Prof. ZHANG Qi-Bin. "Signals from the macroclimate must be extracted efficiently while removing the nonclimate noise embedded in the tree rings."
Changes in climate have dramatic effects on natural ecosystems and human society. Less well understood is whether these changes are irreversible beyond a certain tipping point, that is, whether they represent a climate regime shift.
Scientists worldwide are alarmed about the potential risks of abrupt climate changes and their impacts on ecosystems and society, yet it is still difficult to identify the exact occurrence of climate regime shifts.
To judge whether climate systems undergo regime shifts from one steady state to another, scientists must understand the natural range of climate variability over a time scale that is much longer than the new regime.
ZHANG Peng et al. compiled tree-ring width data from 76 sites throughout inner East Asia and successfully screened 20 sites with strong signals of summer heatwave frequency and soil moisture content.
They found that the magnitude of the warm and dry anomalies compounding in the past two decades is unprecedented over the past 260 years. They further illustrated that the heatwaves and droughts became tightly coupled, which is likely caused by a pronounced enhancement of land-atmosphere coupling along with anthropogenic climate change.
However, it is still challenging for scientists to disentangle the interaction of climate variables and clarify whether these interactions generate negative or positive feedbacks, according to Prof. ZHANG Qi-Bin and Dr. FANG.
Furthermore, spatial differences related to climate regime shifts are worthy of study.
Using tree-ring data as a proxy for past climate variability and forest dynamics, Prof. ZHANG Qi-Bin's lab has long been engaged in investigating the responses of tree growth to multiple dimensions of climate change and ecological disturbances, and in exploring spatial and temporal patterns of forest health.
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Natural resources governance -- responsibilization of citizens or forcing responsibility on them?
The possibilities of citizens to participate in natural resource governance are increasing. Responsive and collaborative models of natural resource governance can open up new opportunities, but can also lead to unreasonable responsibilization, or even force responsibility on under-resourced organisations and individuals. This is the conclusion made in studies published in the Special Issue of Journal of Forest Policy and Economics, entitled Responsibilization in Natural Resource Governance and edited by Professor of Natural Resources Governance Irmeli Mustalahti from the University of Eastern Finland and Professor of Natural Resources & Environment Arun Agrawal from the University of Michigan.
The studies included in the Special Issue deal with natural resources governance in Indonesia, India, Mexico, Nepal, Tanzania and Russia, and show that natural resources governance involves a plethora of different actors for whom responsibilization has become more the rule than the exception. Often, local communities were given increasing responsibility for natural resources governance - without being given appropriate resources or operating conditions. In some cases, responsibilization had changed from mildly persuasive, to demanding, then to forced responsibility.
"The shift from responsibilization to forcing responsibility on local communities can be described as symbolic violence. Obligations and demands dictated from above are often a form of soft and invisible violence that can lead to corruption, social inequalities and exhaustion of natural resources," says Professor Irmeli Mustalahti.
The term symbolic violence was coined by Pierre Bourdieu, a sociologist and philosopher who observed and identified symbolic violence in nearly all power structures that societies have.
"In Finland, too, responsibilization has become an important objective, a tool for enhancing efficiency," says Professor Mustalahti.
She points out that some structures of governance and top-down demands do not necessarily support the well-being of citizens but instead force responsibility on them and are, in fact, manifestations of symbolic violence. Young people, too, are affected. This is a theme addressed also by the ALL-YOUTH research project which is supported by the Strategic Research Council coordinated at the Academy of Finland.
Professor Mustalahti and Professor Agrawal point out in their article that responsibilization and forced responsibility is not an issue in natural resources governance alone; the education and health care sectors are also affected. For example obligations can be transferred or reassigned to local communities, patients or students without giving them proper resources and operating conditions. In public discourse, forcing responsibility on citizens has been justified for reasons pertaining to climate, economy and labour policy.
"In order to support responsible and collaborative governance of natural resources, we need to have better understanding of citizens' skills and abilities, and of social structures and agency. Citizens must have adequate operating conditions, and tasks assigned to them must be in line with their resources and possibilities to influence," says Professor Mustalahti.
Early populations shifted from quasi-egalitarian hunter-gatherer societies to communities governed by a centralized authority in the middle to late Holocene, but how the transition occurred still puzzles anthropologists. A University of Maine-led group of researchers contend that population size and density served as crucial drivers.
Anthropology professor Paul "Jim" Roscoe led the development of Power Theory, a model emphasizing the role of demography in political centralization, and applied it to the shift in power dynamics in prehistoric northern coastal societies in Peru.
To test the theory, he, Daniel Sandweiss, professor of anthropology and Quaternary and climate studies, and Erick Robinson, a postdoctoral anthropology researcher at Utah State University, created a summed probability distribution (SPD) from 755 radiocarbon dates from 10,000-1,000 B.P., or before present.
The team found a correlation between the tenets of their Power Theory, or that population density and size influence political centralization, and the change in power dynamics in early Peruvian societies.
The team shared their findings in a report published in Philosophical Transactions of the Royal Society B.
"I've always been interested in how, in the space of just five to 10,000 years, humans went from biddy little hunter-gatherer groups in which nobody could really push anyone else around to vast industrial states governed by a few people with enormous power. From my fieldwork and other research in New Guinea, it became clear that leaders mainly emerged in large, high-density populations, and Power Theory explained why," Roscoe says. "Unfortunately, it was difficult until recently for archaeologists to get a handle on the size and densities of populations in the past. SPD techniques are a major help in bringing these important variables into understanding how human social life underwent this dramatic transformation."
Scientists have previously posited that population in northern coastal Peru rose during the Late Preceramic, Initial, Early Horizon and Early Intermediate periods, or between about 6,000-1,200 B.P. The SPD from Roscoe and his colleagues validates the notion.
The people who settled in the coastal plain first lived as mobile hunter-gatherers or incipient horticulturalists in low density groups, according to researchers. Millennia afterward in the Late Preceramic period, however, several developments brought increased interaction and shareable resources. People began farming, developed irrigation systems and became more settled as time passed. Eventually, some of the world's first 'pristine' states formed in the plain.
The onset and growth of agriculture, irrigation and sedentism, propelled by upticks in population size and density, fostered the capacity of political agents to interact with and manipulate others. Political centralization and hierarchy formed as a result, according to researchers.
Roscoe and his colleagues demonstrated through their radio-carbon SPD that the rise in centralized authorities in early Peruvian communities that resulted from farming, irrigation and settlement coincided with an uptick in population size. The results of their work demonstrate "a broad, low-resolution congruence between the expectations of Power Theory and what is currently known about coastal Peruvian antiquity," they wrote in their study.
The project also highlights the capability of SPDs for examining the influence of demography in the growth of prehistoric political centralization. Determining the extent of that influence, however, requires additional study.
"We're hoping this work demonstrates the value of SPDs for understanding the role of demography in the emergence and development of power centers on Earth," Roscoe says. "What we need now is to increase the size of our SPD databases and filter out some of the weaknesses we know they contain."
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Study identifies countries and states with greatest age biases
IMAGE: TWO STUDIES FROM MICHIGAN STATE UNIVERSITY PINPOINT WHERE IN THE WORLD YOU'LL FIND THE MOST AGE BIAS, AND WHERE THE "GOLDEN YEARS " ARE CONSIDERED TRULY GOLDEN. view more
CREDIT: CREATIVE COMMONS VIA PXHERE
Elders are more respected in Japan and China and not so much in more individualistic nations like the United States and Germany, say Michigan State University researchers who conclude in a pair of studies that age bias varies among countries and even states.
"Older adults are one of the only stigmatized groups that we all become part of some day. And that's always struck me as interesting -- that we would treat so poorly a group of people that we're destined to become someday," said William Chopik, assistant professor of psychology and author of the studies. "Making more equitable environments for older adults are even in younger people's self-interests."
While aging is looked at as something that's inevitable and a part of everyone's life, it's viewed very differently around the world and in different environments - which could be detrimental for people's health and well-being.
For both studies, Chopik and colleagues gauged public sentiment and biases toward aging by administering the Implicit Association Test -- which measures the strength of a person's subconscious associations -- on over 800,000 total participants in each study from the Project Implicit database.
The first study examined which countries around the world showed the greatest implicit bias against older adults. Published in Personality and Social Psychology Bulletin, the study is the largest study of its kind and was co-authored by Lindsay Ackerman, a post-Baccalaureate researcher in MSU's psychology department.
"In some countries and cultures, older adults fair better, so a natural question we had was whether the people living in different countries might think about older adults and aging differently. And, maybe that explains why societies are so different in the structures put in place to support older adults," Chopik said.
Collectivistic countries like Japan, China, Korea, India and Brazil -- which tend to focus on group cohesion and harmony -- had much less of a bias toward older people than individualistic countries. Individualistic countries like United States, Germany, Ireland, South Africa and Australia tend to stress independence and forging one's own identity. In addition to having greater age biases, the findings also revealed that individualistic countries are more focused on maintaining active, youthful appearances.
"Countries that showed high bias also showed an interesting effect when you asked people how old they felt. In ageist cultures, people tended to report feeling particularly younger than their actual age," Chopik said. "We interpreted this as something called age-group dissociation -- or, feeling motivated to distance yourself from that group. People do this is by identifying with younger age groups, lying about their age and even saying that they feel quantitatively younger than they actually are."
The second study honed in on individual states across the U.S. to see which demonstrated the most age bias, as well as how this bias was associated health outcomes. As the first and only study of its kind, the findings were published in European Journal of Social Psychology and the paper was co-authored by Hannah L. Giasson, a post-doctoral scholar from Stanford University.
The states with the highest age bias were mostly in the Southern and the Northeastern U.S. Additionally, many of most-biased states tended to have the worst outcomes and life expectancies for older adults.
"We found a strange pattern in which some popular retirement destinations tended to be higher in age bias, like Florida and the Carolinas," Chopik said. "Possibly, this could be due to the friction that occurs when there are large influxes and migrations of older adults to regions that are not always best suited to welcome them."
Additionally, states with higher age bias also tended to have higher Medicare costs, lower community engagement and less access to care. Chopik explained that one reason for the added health expenditures is because older adults with more illnesses cause a higher demand for health resources. The other reason is that those states might be worse at managing and administering support and funds for older adults. States -- and how they treat older adults -- likely affect how easily people can acquire these funds and services, he said.
"Both of our studies demonstrate how local environments affect people's attitudes and the lives of older adults. We grow up in our environments and they shape us in pretty important ways and in ways we don't even realize," Chopik said. "Being exposed to policies and attitudes at a country level can shape how you interact with older adults. At the state level in the United States, how you treat older adults has important implications for them -- for example, their health and how long older people live -- and even the economy, like how much money we spend on older adults' health care."
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(Note for media: Please include a link to the original papers in online coverage:
"Geographic Patterns of Implicit Age Bias and Associations with State-level Health Outcomes across the United States" - http://dx.doi.org/10.1002/ejsp.2707)
Covid-19 shutdowns disproportionately affected low-income black households
PRINCETON UNIVERSITY, WOODROW WILSON SCHOOL OF PUBLIC AND INTERNATIONAL AFFAIRS
IMAGE: PRINCETON UNIVERSITY RESEARCHERS NOW REPORT THAT LOW-INCOME BLACK HOUSEHOLDS EXPERIENCED GREATER JOB LOSS, MORE FOOD AND MEDICINE INSECURITY, AND HIGHER INDEBTEDNESS IN THE EARLY MONTHS OF #COVID19 COMPARED TO WHITE... view more
CREDIT: EGAN JIMENEZ, PRINCETON UNIVERSITY
PRINCETON, N.J.--The alarming rate at which Covid-19 has killed Black Americans has highlighted the deeply embedded racial disparities in the U.S. health care system.
Princeton researchers now report that low-income Black households also experienced greater job loss, more food and medicine insecurity, and higher indebtedness in the early months of the pandemic compared to white or Latinx low-income households.
Published in the journal Socius, the paper provides the first systematic, descriptive estimates of the early impacts of Covid-19 on low-income Americans. The findings paint a picture of a deepening crisis: between March and mid-June 2020, an increasing number of low-income families reported insecurity. Then they took on more debt to manage their expenses.
The paper used data from "Fresh EBT," a budgeting app for families who receive Supplemental Nutrition Assistance Program (SNAP) benefits, to provide the first systematic, descriptive estimates of the early impacts of Covid-19 on low-income Americans.
"Media coverage has focused on the racially disparate effects of Covid-19 as a disease, but we were interested in the socioeconomic effects of the virus, and whether it tracked a similar pattern," said study co-author Adam Goldstein, assistant professor of sociology and public affairs at Princeton's School of Public and International Affairs.
"It became clear that while all low-income households struggled in the early months of the pandemic, Black households in America were disproportionately affected. Even among low-income populations, there is a marked racial disparity in people's vulnerability to this crisis," said study co-author Diana Enriquez, a doctoral candidate in Princeton's Department of Sociology.
Enriquez and Goldstein set out to determine the economic impacts of Covid-19 on Americans of lesser means and the racial disparities within that socioeconomic group. They investigated a set of factors related to families' ability to satisfy basic needs including job loss, debt, housing instability, and food and medicine insecurity.
The researchers directly surveyed people who utilize the SNAP and Temporary Assistance for Needy Families (TANF) benefits. Study participants, who were already low-income and benefits-eligible before Covid-19, were surveyed through between the end of March and mid-June. Goldstein and Enriquez chose this time period because shutdowns were already beginning to affect Americans' economic livelihoods, but their economic status had not yet been completely transformed.
People were queried about their current and perceived status related to employment, housing, food and medicine accessibility, and debt load. For example, respondents were asked if they had stable housing, and if they believed their housing would be stable after that 30-day period.
They found that people who receive government assistance experienced pronounced effects in all areas except housing. Nearly 35% of all respondents reported losing their jobs by mid-June.
Financial strain and debt accrual also worsened significantly: 67% of people said they skipped paying a bill at the beginning of the shutdown. In each survey wave between the end of April and mid-June, 77% of households reported missing a bill or rent payment. And, despite being covered by SNAP, 54% of people said they skipped meals, relied on family or friends for food, or visited a food pantry due to the Covid-19 shutdown. By the end of the month, this figure rose to 64%.
When the researchers looked at the data by race, it became clear that low-income Black households fared worse than low-income White households on average. Low-income Latinx respondents fared worse than White households on some indicators, but not on others.
At the beginning of the April 2020, 30% of Black respondents reported that they or someone in their household had lost work during the shutdown. By the end of the month, that number increased to 48%. Likewise, 80% of Black households also reported taking on more debt to cover their bills by the end of April. In mid-June, rates of new debt were similar for Black and Latinx households (more than 80%), while approximately 70% of White households reported new debt.
"The survey results really reinforce the extent to which the Covid-19 crisis has kneecapped those households who were already in a tenuous position near the poverty line. Research shows that these types of debts and unpaid bills -- even small ones -- can compound over time and trap low-income households in a cycle of financial distress," Goldstein said.
"Even in a miraculous scenario where the pandemic ends in a few months and low-wage workers are rehired, tens of millions of households will still find themselves stuck in a financial hole without additional infusions of economic relief," he said.
The authors outline the study's limitations and possible future research avenues. First, the researchers focused on the prevalence of these insecurities, not their severity. They did not measure how many meals were being skipped, for example, or the compounding effects of additional debt. This, as well as other forms of insecurity like access to healthcare or treatment for Covid-19, could be addressed in future work.
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The paper, "COVID-19's Socio-Economic Impact on Low-Income Benefit Recipients: Early Evidence from Tracking Surveys," was published online at Socius in November 2020.
Worst-case emissions projections are already off-track
IMAGE: A PLENARY AT THE 25TH CONFERENCE OF THE PARTIES, HELD BY THE UNITED NATIONS FRAMEWORK CONVENTION ON CLIMATE CHANGE IN DECEMBER 2019. view more
CREDIT: UNFCCC / UNCLIMATECHANGE, FLICKR
Under the worst-case scenarios laid out in the United Nations' climate change projections, global temperatures would increase more than 3.6 degrees Fahrenheit (2 degrees Celsius) by 2100, leading to at least 1.5 feet (0.5 meters) in global sea level rise and an array of disastrous consequences for people and planet. But new research from the University of Colorado Boulder finds that these high-emissions scenarios, used as baseline projections in the UN's Intergovernmental Panel on Climate Change (IPCC) global assessments, have not accurately reflected the slowing rate of growth in the global economy and we are unlikely to catch up to them anytime soon.
The new study, published today in Environmental Research Letters, is the most rigorous evaluation of how projected climate scenarios established by the IPCC have evolved since they were established in 2005.
The good news: Emissions are not growing nearly as fast as IPCC assessments have indicated, according to the study's authors. The bad news: The IPCC is not using the most accurate and up-to-date climate scenarios in its planning and policy recommendations.
"If we're making policy based on anticipating future possibilities, then we should be using the most realistic scenarios possible," said Matt Burgess, lead author on the study and a fellow at the Cooperative Institute for Research in Environmental Sciences (CIRES) at CU Boulder. "We'll have better policies as a result."
The IPCC was established in 1988 and provides policymakers around the globe with regular research-based assessments on the current and projected impacts of climate change. Its reports, the sixth of which is due out in 2022, play an instrumental role in shaping global climate policy.
To see if IPCC scenarios are on track, the researchers compared projections from the latest report, published in 2014, and data used to prepare the upcoming report, to data gathered from 2005 to 2017 on country-level gross domestic product (GDP), fossil-fuel carbon dioxide emissions, likely energy use and population trends during this century. Burgess and his co-authors show that even before the pandemic, due to slower-than-projected per-capita GDP growth, as well a declining global use of coal, these high-emissions scenarios were already well off-track in 2020, and look likely to continue to diverge from reality over the coming decades and beyond. The COVID-19 pandemic's dampening effect on the global economy only accentuates their findings, they said.
As a result, they contend that these high-emissions scenarios should not be used as the baseline scenarios in global climate assessments, which aim to represent where the world is headed without additional climate mitigation policy.
When it comes to climate change scenarios, some scientists and climate experts fear that economic growth will be higher than the projected scenarios, and we'll be taken by surprise by climate changes. But that is unlikely to happen, according to Burgess, assistant professor in environmental studies and faculty affiliate in economics.
This new research adds to a growing literature that argues that economic growth and energy use are currently over-projected for this century. The research also points out that the high-emissions scenarios used by the IPCC don't fully account for economic damages from climate change.
The researchers recommend that these policy-relevant scenarios should be frequently recalibrated to reflect economic crashes, technological discoveries, or other real-time changes in society and Earth's climate. Anticipating the future is difficult and updates are to be expected, according to Roger Pielke Jr., co-author on the paper and professor of environmental studies.
Their study does not mean that people can let their guard down when it comes to addressing climate change, the authors stress. No matter the scenario, the only way to get to net zero emissions as a society is to dramatically reduce carbon dioxide emissions from our energy sources.
"We're still affecting the climate and the challenge of reducing emissions is as hard as ever," said Pielke Jr. "Just because it's not the worst-case scenario doesn't mean that the problem goes away."
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Additional co-authors on this paper include John Shapland in Environmental Studies at CU Boulder and Justin Ritchie of the University of British Columbia's Institute for Resources, Environment and Sustainability.
Tipping point for the climate can already be a reality in East Asia
IMAGE: GRASSLAND IN INNER MONGOLIA, NORTHERN CHINA view more
CREDIT: HANS LINDERHOLM
The climate in inner East Asia may already have reached a tipping point, where recent years' transition to abnormally hot and dry summers can be irreversible. This is the finding of a new international study by researchers at University of Gothenburg now published in Science.
Associated with the ongoing global warming, are changes that impact regional climate and ecosystems. In a worst- case scenario, these can reach what is known as a tipping point, at which point changes are fast and often times irreversible. Examples of tipping points are the sea ice in the Arctic disappearing in the summer or the melting of the Greenland ice-sheet.
Inner East Asia is a sensitive area
Inner East Asia, which includes Mongolia and nearby areas, is a sensitive region that has experienced a clear increase in the number of heat waves during the summer in recent decades. Together with stable high-pressure systems, which raise temperatures, reduced soil moisture can cause intense and long-lasting heat waves because of enhanced interaction between the land surface and the atmosphere.
"What this connection looks like in a longer preindustrial context is, however, unknown since long-term observations do not exist," says Deliang Chen, co-author to the study and leader of the Regional Climate Group (RCG) at the University of Gothenburg.
Annual growth rings from trees provide information on changes that effect their growth and this can be used to study changes in climate in the past.
"By choosing trees whose growth are sensitive to weather variations, the annual rings can be used to reconstruct different climate parameters with annual resolution hundreds of years back in time. Since trees have significant geographic coverage, this data can be used for detailed studies of climate changes over large areas," says Hans Linderholm, co-author of the study and head of the Gothenburg University Laboratory for Dendrochronology (GULD).
Study of tree rings showed a tipping point is close
Long-term observations of soil moisture are rare, but tree rings from trees, which are limited by access to water, can be used as indicators of this parameter. In the same way, trees that grow at high altitudes, where the growing season is short and cool, can be used to provide temperature-related information.
"In this study, we developed a new method for reconstructing both variations in soil moisture and changes in frequency of heat waves in inner East Asia, a region where the interaction between these parameters is very strong," says Peng Zhang, first author of the study and researcher in the Regional Climate Group at the University of Gothenburg.
These new reconstructions allow the scientists to study the recent warm and dry summers in a long-term perspective. The results show that the current high frequency of heat waves and low soil moisture have not been observed during the last 260 years.
"By combining observations, reconstructions and climate model data, we discovered that the link between land surface and atmosphere has become more pronounced in inner East Asia over the last 20 years, along with increased drying of soils. So we argue that reduced soil moisture enhances land-atmosphere coupling contributing to heating of the land surface, which causes more heat waves, which in turn reduces soil moisture and so on," says Peng.
The study's authors found that the recent pattern of increased warming and drought indicate that a tipping point in the climate is close, a change that could be irreversible and lead to a much dryer climate in the region.
"This would increase the stresses of ecosystems and societies in this already vulnerable region," says Peng.
IMAGE: THE BRAHMAPUTRA RIVER, SEEN HERE FROM A FERRY IN BANGLADESH, WHERE IT IS KNOWN AS THE JAMUNA. IT IS AT POINTS NEARLY TOO WIDE TO SEE BANK TO BANK. view more
CREDIT: KEVIN KRAJICK/EARTH INSTITUTE
A new study looking at seven centuries of water flow in south Asia's mighty Brahmaputra River suggests that scientists are underestimating the river's potential for catastrophic flooding as climate warms. The revelation comes from examinations of tree rings, which showed rainfall patterns going back centuries before instrumental and historical records.
Many researchers agree that warming climate will intensify the seasonal monsoon rains that drive the Brahmaputra, but the presumed baseline of previous natural variations in river flow rests mainly on discharge-gauge records dating only to the 1950s. The new study, based on the rings of ancient trees in and around the river's watershed, shows that the post-1950s period was actually one of the driest since the 1300s. The rings show that there have been much wetter periods in the past, driven by natural oscillations that took place over decades or centuries. The takeaway: destructive floods probably will come more frequently than scientists have thought, even minus any effects of human-driven climate change. Estimates probably fall short by nearly 40 percent, say the researchers. The findings were just published in the journal Nature Communications.
"The tree rings suggest that the long-term baseline conditions are much wetter than we thought," said Mukund Palat Rao, a recent PhD. graduate of Columbia University's Lamont-Doherty Earth Observatory and lead author of the study. "Whether you consider climate models or natural variability, the message is the same. We should be prepared for a higher frequency of flooding than we are currently predicting."
The Brahmaputra is one of the world's mightiest rivers, flowing under a variety of names and braided routes some 2,900 miles through Tibet, northeast India and Bangladesh. Near its mouth, it combines with India's Ganga River to create the world's third largest ocean outflow, behind only the Amazon and the Congo. (It is tied with Venezuela's Orinoco.) At points, it is nearly 12 miles wide. Its delta alone is home to 130 million Bangladeshis, and many millions more live upstream.
The river routinely floods surrounding areas during the July-September monsoon season, when moisture-laden winds sweep in from the Indian Ocean and bring rain along its length, from its Himalayan headwaters on down to the coastal plain. As with the Nile, the flooding has a good side, because the waters drop nutrient-rich sediment to replenish farmland, and some degree of flooding is essential for rice cultivation. But some years, the flooding runs out of control, and low-lying Bangladesh gets hit hardest. In 1998, 70 percent of the country went underwater, taking out crops, roads and buildings, and killing many people. Other serious floods came in 2007 and 2010. In September 2020 the worst flooding since 1998 was still underway, with a third of Bangladesh inundated, and 3 million people rendered homeless.
Higher temperatures drive more evaporation of ocean waters, and in this region that water ends up as rainfall on land during the monsoon. As a result, most scientists think that warming climate will intensify the monsoon rains in coming decades, and in turn increase seasonal flooding. The question is, how much more often might big floods happen in the future?
The authors of the new study first looked at records from a river-flow gauge in northern Bangladesh. This showed a median discharge some 41,000 cubic meters per second from 1956 to 1986, and 43,000 from 1987 to 2004. (In the big flood year of 1998, peak discharge more than doubled.)
They then looked at data from the rings of ancient trees that researchers sampled at 28 sites in Tibet, Myanmar, Nepal and Bhutan, at sites within the Brahmaputra watershed, or close enough to be affected by the same weather systems. Most samples were taken from conifer species in the last 20 years by scientists from the Lamont-Doherty Tree Ring Lab, led by study coauthor Edward Cook. Since people have long been cutting down trees in populous areas, Cook and his colleagues sometimes hiked for weeks to reach undisturbed sites in remote, mountainous terrain. Straw-width samples were bored from trunks, without damage to the trees. The oldest tree they found, a Tibetan juniper, dated to the year 449.
CAPTION
Scientists calculated past rainfall and river discharges by measuring the rings of ancient trees within or near the Brahmaputra watershed. Here, researcher Dorji Dukpa of Bhutan's Department of Forest and Park Services extracts a core from a Himalayan hemlock.
CREDIT
Paul Krusic/University of Cambridge
Back at the lab, they analyzed the tree rings, which grow wider in years when soil moisture is high, and thus indirectly reflect rainfall and resulting river runoff. This allowed the scientists to assemble a 696-year chronology, running from 1309 to 2004. By comparing the rings with modern instrumental records as well as historical records going back to the 1780s, they could see that the widest rings lined up neatly with known major flood years. This in turn allowed them to extrapolate yearly river discharge in the centuries preceding modern records. They found that 1956-1986 was in only the 13th percentile for river discharge, and 1987-2004 in the 22nd.
This, they say, means that anyone using the modern discharge record to estimate future flood hazard would be underestimating the danger by 24 to 38 percent, based solely on natural variations; human driven warming would have to be added on top of that. "If the instruments say we should expect flooding toward the end of the century to come about every four and a half years, we are saying we should really expect flooding to come about every three years," said Rao.
The tree rings do show some other relatively dry times, in the 1400s, 1600s and 1800s. But they also show very wet periods of extreme flooding with no analog in the relatively brief modern instrumental period. The worst lasted from about 1560-1600, 1750-1800 and 1830-1860.
Climate change will almost certainly affect the flow of other major rivers in the region, though not necessarily in the same ways. The mighty Ganga, flowing mainly through India, is also powered mainly by the monsoon, so it will likely behave much like the Brahmaputra. But the Indus, which flows through Tibet, India and Pakistan, derives most of its flow not from the monsoon, but rather from the winter buildup of snow and ice in Himalayan glaciers, and subsequent melting in summer. In 2018 Rao and colleagues published a tree-ring study showing that the river's flow has been anomalously high in recent years. They suggest that as climate warms and the glaciers undergo accelerated melting, the Indus will supply plenty of needed irrigation water--but at some point, when the glaciers lose enough mass, the seasonal spigot will turn the other way, and there may not be enough water.
Human vulnerability to floods along the Brahmaputra has increased in recent years due not only to sheer water volume, but because population and infrastructure are growing fast. On the other hand, accurate flood warnings have become more advanced, and this has helped many villages reduce economic and social losses. "High discharges will continue to be associated with an increased likelihood of flood hazard in the future," write the study authors. But, they say, this could be counteracted to some extent by "potential changes in policy, land use, or infrastructure that may ameliorate flood risk."
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The study was also coauthored by Benjamin Cook, Rosanne D'Arrigo, Brendan Buckley and Daniel Bishop, all affiliated with the Lamont-Doherty Tree Ring Lab; Upmanu Lall of the Columbia Water Center; Columbia University ecologist Maria Uriarte; and collaborators at other U.S. universities and in Australia and China.
CAPTION
Low-lying land along the river in Bangladesh frequently floods during rainy season. This can benefit crops, but can also lead to massive destruction when it goes too fa
More information: Kevin Krajick, Senior editor, science news, The Earth Institute kkrajick@ei.columbia.edu 212-854-9729
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Pyroclasts protect the paintings of Pompeii buried but damage them when they are unearthed
They may produce salts in artworks, the IBeA group of the UPV/EHU-University of the Basque Country has concluded
IMAGE: DR MAITE MAGUREGUI OF THE IBEA GROUP TAKING MEASUREMENTS IN THE MURAL PAINTINGS OF POMPEII USING PORTABLE TOOLS. view more
CREDIT: IBEA / UPV/EHU
The ancient city of Pompeii (in the south of Italy) ended up buried under ash and volcanic material in 79 CE as a consequence of the eruption of Mount Vesuvius. That fateful event made the unprecedented conservation of the archaeological site in the area possible because the pyroclastic materials spewed out by Vesuvius have protected the remains from external damage. So not only in cultural but also in scientific terms they are in fact highly prized sites where tourists and professionals of archaeology and even chemistry mingle.
For over 10 years the UPV/EHU's IBeA group, attached to the department of Analytical Chemistry, has been working at Pompeii within the framework of the Analytica Pompeiana Universitatis Vasconicae-APUV project. In 2015 the UPV/EHU and the Archaeological Park of Pompeii signed the first of the agreements thanks to which the methodologies and portable devices used by the research group are allowing the paintings to be analysed using non-destructive techniques.
Various studies conducted at the House of Marcus Lucretius, the House of Ariadne and the Casa degli Amorini Dorati or House of the Golden Cupids have concluded that "salts are responsible for the worst and most visible damage to the murals. In the end, the salts may dissolve and as a result material such as pigments, the pictorial layer, the mortar, etc. may be lost", said Maite Maguregui, lead researcher in this study. In this respect, the researchers have concluded that the leached ions from the pyroclastic materials and the ion-rich underground waters from the volcanic rocks promote the crystallization of certain salts.
"While the paintings remain underground, they are protected by the pyroclasts; but once they are brought to the surface, the salts start to form owing to the effect of the air, humidity, etc. So in order to conserve the mural paintings it is important to know in each case what the salt load of the surrounding pyroclasts is to be able to block, reduce or prevent potential damage. In fact, in Pompeii a large proportion remains buried and waiting to be studied," added Maguregui.
Fluorine marking the impact of the volcanic materials
"When the volcano erupted, it spewed out huge quantities of materials and the pyroclastic material is not homogeneous across the whole area; many different strata can be found," explained the researcher. Mineralogical analyses of samples collected at various points were made in the study, and the compositions of the leachates were determined. Thermodynamic modelling was also carried out to predict which salts can precipitate as a result of leaching and to determine their origins. It was concluded that the salts provided by the modelling coincide with those detected in the paintings.
The salts analysed in the murals contain fluorine ions, among other things. "Fluorines are ions of volcanic origin; it is not one of the main elements in the atmosphere. The emergence of fluorine salts indicates that the volcanic materials and the subterranean waters are exerting an influence on the crystallization of these salts," she explained. "So with the fluorine found in the mural it is possible to trace the impact that has been exerted and continues to be exerted by the pyroclasts and the subterranean waters on the paintings." The group's next aim would be to "map the murals on a large scale to see the extent of the salts and also to be able to determine the steps to be followed by the conservation staff when they unearth a mural painting", she added.
