Improved prediction of Indian Monsoon onset three months in advance using machine learning

The result is encouraging as the Indian monsoon might become less regular due to future global warming

UNIVERSITY OF COPENHAGEN - FACULTY OF SCIENCE

Research News

 

IMAGE: THE FINDINGS IN BRIEF. view more 

CREDIT: TIPES/HP

The onset of the Indian summer monsoon has been predicted three months ahead for the last 40 years with the highest precision up until today. The result indicates longer seasonal forecasts based on machine learning may be a way to mitigate the consequences of an erratic monsoon system under future global warming. Dr. Takahito Mitsui and Dr. Niklas Boers of the Potsdam Institute of Climate Impact Research (PIK Potsdam), Germany, published the results in Environmental Research Letters. The work is part of the European TiPES project, Coordinated from The Niels Bohr Institute, University of Copenhagen, Denmark and PIK Potsdam.

Millions of people as well as natural habitats depend on the precipitation from the Indian summer monsoon. Global warming, however, is already changing the monsoon system and will further increase the variation in precipitation patterns as well as monsoon onset and duration in the future. Seasonal forecasts might provide early warnings for farmers and others depending on the Indian monsoon to plan ahead and mitigate the consequences of interannual variabilities.

Climate scientists from PIK Potsdam, Germany now provide an improved three-month preseasonal forecast using machine learning. The predictions use data since 1948 and thus cover the climate changes of the latest decennia. The work provides a promising basis for further research toward predicting the onset of the Indian summer monsoon in the coming decades, as accelerated global warming might change the dynamics behind this monsoon system.

Comparing reconstructed data of tropospheric temperatures over the Indian Ocean and the Indian subcontinent the scientists used a shift in temperature balance between two areas to predict the monsoon onset. The resulting accuracy of +/- 4.8 days is an improvement compared to earlier attempts using traditional weather prediction models to forecast the Indian monsoon onset in a three months range.

"We can confirm with a level of optimism that it should be possible to predict the onsets of future monsoons even as global climate change accelerates in the coming decades. Indeed, our prediction method works well for the last 40 years, during which gradual global warming already has taken place," says Takahito Mitsui.

"Our study reveals the large potential of machine learning methods in forecasting climate phenomena such as the monsoon onset. Ultimately, our goal is to combine traditional weather prediction models with machine learning models such as the one proposed here, which will hopefully lead to even more skilful forecasts," says Niklas Boers.

The possibility of accurate predictions in a world with a much higher global warming, however, has not yet been investigated. The outlook for the Indian monsoon system in a changing global climate is scientifically debated. The current monsoon system might tip to a more irregular state. But it might also simply change gradually as the seasonal imbalances between the temperatures over regional landmasses and sea surfaces shift with global warming.

"We will be able to examine this with the climate model simulations under global warming scenarios. Then we will be able to answer more confidently if our method can, or cannot predict some possible failure in the Indian Monsoon system in advance," says Takahito Mitsui.

The TiPES project is an EU Horizon 2020 interdisciplinary climate science project on tipping points in the Earth system. 18 partner institutions work together in more than 10 countries. TiPES is coordinated and led by The Niels Bohr Institute at the University of Copenhagen, Denmark and the Potsdam Institute for Climate Impact Research, Germany.

The TiPES project has received funding from the European Horizon 2020 research and innovation program, grant agreement number 820970.

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To understand ecology, follow the connections

New research from UMass Amherst suggests that demography is the key to managing habitat loss and fragmentation

UNIVERSITY OF MASSACHUSETTS AMHERST

Research News

IMAGE: WILDLIFE OVERPASS NEAR BANFF NATIONAL PARK. view more 

CREDIT: LUCILLEB/ISTOCK/GETTY IMAGES PLUS

AMHERST, Mass. - City sprawl and road development is increasingly fragmenting the habitats that many plant and animal species need to survive. Ecologists have long known than sustainable development requires attention to ecological connectivity - the ability to keep plant and wildlife populations intact and healthy, typically by preserving large tracts of land or creating habitat corridors for animals. New research from the University of Massachusetts Amherst argues that it's not enough for ecological modelling to focus on the landscape. If we want the best-possible ecological management, we should consider when and where individuals are located.

"Everybody needs a place to live," says Joseph Drake, a graduate student in the department of environmental conservation and the organismic and evolutionary biology program at UMass, and the lead author of the research that appeared recently in Ecography. "Humans build roads, but animals and plants have pathways. Movement along the pathways are essential to the continued persistence of plant and animal populations." This is where connectivity comes in, and there are two traditional ways of modelling it. One, the structural approach, focuses on where suitable habitats are and whether or not these habitats are contiguous, connected via corridors, or broken up and widespread. The other definition, functional connectivity, considers how species respond in relation to the habitats they move through.

But, says Drake, it's not enough to focus on either the structural or functional aspects of connectivity. Instead, a third aspect - demography - needs to be combined with the other two. "If we wish to understand how human activities influence plants and wildlife," says Drake, "then we need to know where the animals and plants actually are, where they want to be and how they move." Drake and his co-authors advocate for a "demographically weighted approach," which substantially improves the ability of ecological models to mirror observed reality. Indeed, the authors show that ignoring demography can markedly reduce the performance of ecological models, which has real-world implications for species' chances of survival.

Furthermore, the weighted approach is better not only at understanding populations of plants and animals as they are now, but in the future, as well. As plants and animals continue to adapt to climate change by moving across the landscape, understanding how species' dispersal affects their existence will take on growing importance.

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Contacts: Joseph Drake, jdrake@umass.edu Daegan Miller, drmiller@umass.edu

 

Worms learn how to optimize foraging by switching their response to social cues

Worms optimise their foraging behaviour by learning to associate pheromones with food availability and changing their movements accordingly

ELIFE

Research News

IMAGE: AN IMAGE OF A CAENORHABDITIS ELEGANS (C. ELEGANS) WORM. view more 

CREDIT: ADAPTED FROM WORK BY ARNE HENDRIKS (CC BY 2.0 - HTTPS://CREATIVECOMMONS.ORG/LICENSES/BY/2.0)

Researchers have shown how worms learn to optimise their foraging activity by switching their response to pheromones in the environment, according to a report published today in eLife.

The findings are an important advance in the field of animal behaviour, providing new insights on how sensory cues are integrated to facilitate foraging and navigation.

Foraging food is one of the most critical yet challenging activities for animals, with food often patchily distributed and other animals trying to find and consume the same resources.

An important consideration is how long to stay and exploit a food patch before moving on to find another. Leaving incurs the cost of exploring a new territory, whereas staying put means feeding in a patch where resources are depleting. So how do animals know when to leave?

Natural habitats are usually full of chemical cues, such as pheromones from other individuals, and it is thought that pheromones help animals orientate their search for food. This means they need to know whether pheromones point to an abundant food resource, or an already exploited one. To acquire this knowledge, they need to learn from experience.

"It has been shown that bumblebees learn from the positive or negative association with pheromones acquired from their most recent feeding experience, but whether this is the case for other animals is unclear," explains first author Martina Dal Bello, Postdoctoral Associate at the Massachusetts Institute of Technology (MIT), Cambridge, US. "We wanted to investigate the foraging behaviours of Caenorhabditis elegans worms because we know that they can evaluate population density inside food patches using pheromones, and that both pheromones and food availability control when the worms decide to move on to a new food resource."

The team started with a test to assess the worms' patch-leaving behaviour. Worms fed on a small patch of bacteria for about five hours, at equal distance from two spots: one a blend of pheromones and the other a non-pheromone control. The worms left the original patch at very different times; those that left early were more likely to go to the pheromone spot, whereas those that left late avoided the pheromones.

Next, they wanted to test whether these behaviours provided any survival benefits, so they developed a mathematical model to calculate the benefit to the worms of changing their preference for pheromones in a patchy environment. In the model, worms in an already occupied food patch have three choices: remain in their food patch, switch to another occupied food patch, or disperse away to an unoccupied patch. The model showed that the strategy that maximises the food eaten by a worm aligns with what they observed in the previous experiment. A fraction of worms switch at the beginning, leaving the food patch before it is depleted and following pheromones to reach another occupied patch. Then, once the food patches are depleted, all worms will disperse to find other food sources. These late leavers avoid other depleted patches by reversing their preference for pheromones, because they now associate pheromones with a depleted food patch.

So how do the worms know to reverse their preference for pheromones? To find out, the researchers kept worms in four sets of conditions: one with food and pheromones; one with pheromones but without food; one with food but without pheromones; and one without any food or pheromones. They then monitored how the worms reacted to a blend of pheromones. As anticipated, worms that spent time in the presence of both food and pheromones moved towards the pheromone blend, whereas they avoided it if they were used to the environment with pheromones but without food. As with bumblebees, the worms learn to prefer pheromones based on their recent positive or negative experience with foraging.

"Our study explains why worms tend to leave food patches at different times," explains senior author Jeff Gore, Professor of Physics at MIT. "Those that leave early are exposed to pheromones when food is abundant and have a positive association with these cues, which leads them to seek them out again. By contrast, worms that leave later when food is sparse associate pheromones with being famished, and avoid pheromones when they move away from the patch. Taken together, these results show that worms learn to adapt to sensory cues in their environment to optimise food intake during foraging."

About eLife

eLife is a non-profit organisation created by funders and led by researchers. Our mission is to accelerate discovery by operating a platform for research communication that encourages and recognises the most responsible behaviours. We aim to publish work of the highest standards and importance in all areas of biology and medicine, including Ecology, while exploring creative new ways to improve how research is assessed and published. eLife receives financial support and strategic guidance from the Howard Hughes Medical Institute, the Knut and Alice Wallenberg Foundation, the Max Planck Society and Wellcome. Learn more at https://elifesciences.org/about.

To read the latest Ecology research published in eLife, visit https://elifesciences.org/subjects/ecology.

 

From eyebrow beans to 'lost' rice: community seedbanks are protecting China's crops

Despite being relatively new in China, community-led seedbanks are a valuable resource in conserving agricultural biodiversity. For the first time, researchers have provided a comprehensive summary of the services performed by 27 seedbanks across the country

THE ALLIANCE OF BIOVERSITY INTERNATIONAL AND THE INTERNATIONAL CENTER FOR TROPICAL AGRICULTURE

Research News

IMAGE: FARMER VARIETIES IN WANGJINZHUANG VILLAGE, HEBEI PROVINCE. view more 

CREDIT: QIUBI

"Plant a hundred kinds of crops"

Wangjinzhuang village is nestled amongst the steep slopes of the South Taihang Mountains in Hebei Province, China. To prosper in the northern climate, the villagers have developed a tried-and-true strategy: "using the land to plant a hundred kinds of crops and not rely on the sky". Their fields contain red millet, white sorghum, purple and green eyebrow beans, and yellow radishes. Having survived for over a thousand years, this agrobiodiversity is a vibrant cornerstone of the village's agricultural heritage that is too precious to lose.

In an effort to combat dwindling crop diversity across China (the Ministry of Agriculture found that of 11,590 grain crop varieties planted in the country in 1956, only 3,271 varieties remained in 2014), the government has bolstered its system of national genebanks, plus issued recent policy recommendations. These are making positive steps towards large-scale conservation; however, there has been relatively little attention given to the role of the country's 260 million farmers who have saved, used, and contributed to the evolution of diverse, local crops for centuries.

The services provided by China's community seedbanks have been documented for possibly the first time by an article recently published in Frontiers in Sustainable Food Systems. 27 seedbanks were surveyed to understand their ability to meet a wide range of needs, with positive implications for climate resilience, improved farmer livelihoods, and increased food security.

CAPTION

Bringing seed to the community seed bank, Guangxi.

CREDIT

Alliance of Bioversity International and CIAT / Ronnie Vernooy

Seedbanks the Chinese way

The seedbank at Wangjinzhuang village, one of the case studies covered by the article, has quickly grown since its establishment in 2019 by a local farmers' association. Now run by 43 members, 26 of whom are women, the seedbank holds viable samples over a hundred crop varieties, including essential grains such as millets and 82 traditional varieties. Members have organized multiplication plots and stipulate that for 1 kg of seeds withdrawn, 1.5 kg must be returned. This, combined with the guidance of plant breeders and a farmer field school, ensures a future supply of seeds that continue to evolve to meet local environmental conditions.

Elsewhere, in Jiangsu Province (a region with 6,000 years of rice paddy culture), economic development and large-scale agriculture have depleted many aquatic crops. But, spurred by increased consumer demand for sustainable and healthy foods, farmers have begun to turn back towards more diverse traditional rice varieties such as Suyunuo, an aromatic sticky rice that had been abandoned for over two decades. This 'lost' crop diversity is being reintroduced at an organic farm backed up by community seed banking. The community seedbank facilitates farmer-to-farmer exchange of seed and brings new diversity to the area through samples obtained from a regional public genebank. However, farmers realized that they no longer knew how to cultivate Suyunuo for the best results. Only by collaborating with public research institutes is it possible for farmers to re-adapt the crop to match new environmental conditions and consumers' interests.

Article author Dr. Yiching Song from the Chinese Academy of Sciences spearheaded the Farmer Seeds Network, a national initiative that organized many seedbanks. She reflects: "Community seedbanks encourage seed and knowledge exchange within and among rural communities, between rural communities and the formal conservation and seed sectors; and add value to local crop diversity through new linkages with markets and cities."

CAPTION

Wangjinzhuang village's Community Seedbank.

CREDIT

Qiubi

Growing seedbanks across China and beyond

Researchers emphasize the need for policies to recognize the complementary role of community seedbanks within the national conservation system and standardize processes for seed storage and benefit-sharing. Dr. Song notes that a formal system of incentives and rewards would, "encourage farmer communities to establish community seedbanks and work together with plant breeders and other researchers to take care of our country's rich agrobiodiversity."

Further support to develop seedbanks can come through organized training. Ronnie Vernooy is a scientist at the Alliance of Bioversity International and CIAT, which was part of the establishment of China's first-ever community seedbank in 2010. Since then, he says, "The Farmer Seeds Network, using our training handbooks developed for facilitators and farmers, has done remarkable work enabling farmers to open new community seedbanks across China. This is an important and exciting step in building more resilient seed systems."

Takeaways:
* China's wealth of crop biodiversity has been steadily disappearing.
* This can be addressed by community seedbanks, which build on a long tradition of farmer seed saving.
* Policy support and training can ensure that seedbanks are best equipped to conserve biodiversity and provide additional value for farmers.

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Further reading

The community seedbank handbooks developed by the Alliance of Bioversity International and CIAT were revised in 2020, and have been translated into multiple languages to help establish seedbanks in the Horn of Africa. English versions below: Facilitator handbook: Community Seed banks: concept and practice Farmer handbook: 1) How to develop and manage your own community seed bank 2) Technical issues 3) Management, networking, policies and a final checklist

Versions are being made available in English, Chinese, Luo, Ateso, Azandhi, Bari, Dinka, N'dogo, Nuer (South Sudanese), Arabic (Sudanese) and Amharinja, Oromo (Ethiopian).

For more information, please contact scientist Ronnie Vernooy: r.vernooy@cgiar.org

 

What to do with food waste? Well, that depends

NREL researchers examine disposal methods as more landfills prepare to shut down

DOE/NATIONAL RENEWABLE ENERGY LABORATORY

Research News

The expected decline in the number of landfills across the United States coupled with bans on disposing large amounts of organic waste in landfills that have been enacted in multiple states has prompted researchers at the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL) to examine other ways to grapple with the issue of food waste disposal.

The researchers determined no single solution exists in the United States for dealing with food waste disposal. NREL researchers Alex Badgett a­­nd Anelia Milbrandt came to that conclusion after examining the economics involved in five different ways to handle disposing of food waste, including tossing it into a landfill. Both researchers are part of NREL's Strategic Energy Analysis Center.

"If we are trying to develop an optimized waste management system in the U.S. that diverts all food waste from landfills, there is not necessarily any one technology that will work for all areas of the country," Badgett said. "An optimized system would likely use different technologies in different locations and at different sizes."

Badgett and Milbrandt are coauthors of a newly published paper titled "Food waste disposal and utilization in the United States: A spatial cost benefit analysis," which appears in Journal of Cleaner Production.

About 75% of food waste winds up in landfills. But many landfills are running close to capacity and a significant number are scheduled to close by 2050, the researchers found. Although sufficient land is available for new landfills in rural America, residents in more-populated regions will be forced to transport waste long distances for disposal. Secondly, organic waste disposal bans enacted in several states require disposal of food waste in facilities other than landfills. Given a need for investment in new waste management facilities, an opportunity exists for innovative and improved pathways for waste streams. Badgett and Milbrandt examined five options for what to do with food waste, including the continued dumping into landfills. The other four options are:

Anaerobic digestion, in which microorganisms break down biodegradable material in the absence of oxygen

Composting, a biological process involving decomposition of organic matter in a controlled environment to produce compost

Incineration, where trash is burned for heat and/or power

Hydrothermal liquefaction, in which wet organic material is converted into biocrude.

Incineration has fallen out of favor because of increased environmental regulations and public opposition to the construction of new facilities. Hydrothermal liquefaction remains in the pilot stage.

The researchers examined the economics of operating various types of facilities, considering how much revenue each brings in from users or from the sale of products. They modeled the financial viability of the technologies, considering capital and operating costs of the facilities; revenue from the sale of power, heat, fuels, and other products; and production credits such as Renewable Identification Number (RIN) credits under the Renewable Fuel Standard for the generation and use of biogas as vehicle fuel.

All of the ways to handle food waste exhibit some economy of scale (where costs decrease when facilities are built at larger sizes), but the researchers found the rate at which financial viability changes with size of the facility is not consistent. For example, landfills and incinerators designed to treat bulk municipal solid waste, which includes food waste, must be constructed at large sizes in order to leverage economies of scale for these pathways, while digesters and composters can be built at smaller scales and still provide a profitable alternative for food waste disposal.

All the different types of facilities would benefit from developing technologies to produce biogas or related products, but benefits are greatest for those operating at medium to large scales. Facilities that currently accept food waste in large amounts are better suited to maximize the economic benefits associated with producing fuels, power, or products since they have a supply of feedstock readily available.

Waste management facilities charge users a gate fee to offset operating and capital costs. If a facility can produce enough biogas to reduce its dependence on fees, it either becomes more profitable or can reduce those fees to become more competitive.

The location of a facility plays an important role in determining its profitability, the researchers found. For example, states along the East and West coasts have the highest gate fees and are therefore more economically favorable.

DOE's Bioenergy Technologies Office funded the research.

NREL is the U.S. Department of Energy's primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for the Energy Department by the Alliance for Sustainable Energy, LLC.

 

Lab analysis finds near-meat and meat not nutritionally equivalent

Neither is good or bad, they are just not the same, authors say

DUKE UNIVERSITY

Research News

DURHAM, N.C. -- Plant-based meat substitutes taste and chew remarkably similar to real beef, and the 13 items listed on their nutrition labels - vitamins, fats and protein -- make them seem essentially equivalent.

But a Duke University research team's deeper examination of the nutritional content of plant-based meat alternatives, using a sophisticated tool of the science known as 'metabolomics,' shows they're as different as plants and animals.

Meat-substitute manufacturers have gone to great lengths to make the plant-based product as meaty as possible, including adding leghemoglobin, an iron-carrying molecule from soy, and red beet, berries and carrot extracts to simulate bloodiness. The texture of near-meat is thickened by adding indigestible fibers like methyl cellulose. And to bring the plant-based meat alternatives up to the protein levels of meat, they use isolated plant proteins from soy, peas, and other plant sources. Some meat-substitutes also add vitamin B12 and zinc to further replicate meat's nutrition.

However, many other components of nutrition do not appear on the labels, and that's where the products differ widely from meat, according to the study, which appears this week in Scientific Reports.

The metabolites that the scientists measured are building blocks of the body's biochemistry, crucial to the conversion of energy, signaling between cells, building structures and tearing them down, and a host of other functions. There are expected to be more than 100,000 of these molecules in biology and about half of the metabolites circulating in human blood are estimated to be derived from our diets.

"To consumers reading nutritional labels, they may appear nutritionally interchangeable," said Stephan van Vliet, a postdoctoral researcher at the Duke Molecular Physiology Institute who led the research. "But if you peek behind the curtain using metabolomics and look at expanded nutritional profiles, we found that there are large differences between meat and a plant-based meat alternative."

The Duke Molecular Physiology Institute's metabolomics core lab compared 18 samples of a popular plant-based meat alternative to 18 grass-fed ground beef samples from a ranch in Idaho. The analysis of 36 carefully cooked patties found that 171 out of the 190 metabolites they measured varied between beef and the plant-based meat substitute.

The beef contained 22 metabolites that the plant substitute did not. The plant-based substitute contained 31 metabolites that meat did not. The greatest distinctions occurred in amino acids, dipeptides, vitamins, phenols, and types of saturated and unsaturated fatty acids found in these products.

Several metabolites known to be important to human health were found either exclusively or in greater quantities in beef, including creatine, spermine, anserine, cysteamine, glucosamine, squalene, and the omega-3 fatty acid DHA. "These nutrients have potentially important physiological, anti-inflammatory, and or immunomodulatory roles," the authors said in the paper.

"These nutrients are important for our brain and other organs including our muscles" van Vliet said. "But some people on vegan diets (no animal products), can live healthy lives - that's very clear." Besides, the plant-based meat alternative contained several beneficial metabolites not found in beef such as phytosterols and phenols.

"It is important for consumers to understand that these products should not be viewed as nutritionally interchangeable, but that's not to say that one is better than the other," said van Vliet, a self-described omnivore who enjoys a plant-heavy diet but also eats meat. "Plant and animal foods can be complementary, because they provide different nutrients."

He said more research is needed to determine whether there are short-term or long-term effects of the presence or absence of particular metabolites in meat and plant-based meat alternatives.

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No funding was received to perform this work.

CITATION: "A Metabolomics Comparison of Plant-Based Meat and Grass-fed Meat Indicates Large Nutritional Differences Despite Comparable Nutrition Facts Panels," Stephan van Vliet, James Bain, Michael Muehlbauer, Frederick Provenza, Scott Kronberg, Carl Pieper, Kim Huffman. Scientific Reports, July 5, 2021. DOI: 10.1038/s41598-021-93100-3

Online: https://rdcu.be/cnKRJ

 

Studies add to concern about climate tipping

Tipping found in models of the Gulf Stream and North American mid-latitude wind systems add to the growing concern that anthropogenic climate change might be abrupt and irreversible

UNIVERSITY OF COPENHAGEN - FACULTY OF SCIENCE

Research News

IMAGE: PROFESSOR MICHAEL GHIL: "THESE RESULTS INDICATE THAT CLIMATE TIPPING IS AN IMMINENT RISK IN THE EARTH SYSTEM. EVEN THE SAFE OPERATING SPACE OF 1.5 OR 2.0 DEGREES ABOVE PRESENT GENERALLY... view more 

CREDIT: PHILIPPE BRUÈRE

Two model studies document the probability of climate tipping in Earth subsystems. The findings support the urgency of restricting CO2 emissions as abrupt climate changes might be less predictable and more widespread in the climate system than anticipated. The work is part of the European TiPES project, coordinated by the University of Copenhagen, Denmark but was conducted by Professor Michael Ghil, Ecole Normale Supérieure, Paris, France and coauthours from The Royal Meteorological Institute of Belgium and Parthenope University of Naples, Italy.

Tipping could be imminent

It is often assumed climate change will proceed gradually as we increase the amounts of CO2 in the atmosphere. Over the last 15 years, however, it has become increasingly clear that the Earth's climate system or subsystems thereof - such as sea ice cover, monsoon systems, and ocean currents - might shift abruptly and with little warning as CO2 levels go up. This is known as climate tipping.

Two studies from the European TiPES project now add to the evidence that tipping could be imminent and might be more widespread in the climate system than usually anticipated.

El Ninõ tips weather-system

In the first study, the authors show in a coupled ocean-atmosphere model how the mid-latitude wind systems over Europe and North America has a probability to tip between different types of behaviour (or different regimes, as climate scientists say) depending on the strength of an El Niño. In other words, the climate phenomenon El Niño - during which heat builds up in the surface layers of the eastern tropical Pacific Ocean - determines whether the mid-latitude wind system in the U.S.A. will be more or less likely to shift abruptly between one regime and another.

Such probabilistic climate tipping complicates prediction, which is generally based on the assumption that climate systems change gradually in a more predictable manner. The findings, - co-authored with Stéphane Vannitsem and Jonathan Demaeyer from the Royal Meteorological Institute of Belgium and published in Journal of Advances in Modeling Earth Systems, thus explain why the patterns of precipitation and temperature during and after an El Niño, have been difficult to predict with accuracy up till now.

Tipping the Gulf Stream

The other result concerns rate-induced tipping. This kind of climate tipping takes place not because a certain threshold level is reached, like a CO2 level in the atmosphere, but rather because the rate of change is too fast for the system to evolve gradually.

The study - co-authored with Stefano Pierini from the Parthenope University of Naples and published in Scientific Reports, finds rate-induced tipping in a simplified model of the wind-driven ocean circulation for the first time. In this model study, the Gulf Stream - which distributes heat to the North Atlantic and plays an important role in keeping the temperatures in Western Europe relatively mild - tips between regimes when CO2 is introduced at a rapid rate into the model.

A real risk

Such a result is highly relevant as levels of CO2 in the atmosphere currently go up at an unprecedented rate. If the Gulf Stream eventually tips in this rate-induced manner, Western Europe could experience rather abrupt changes to its climate.

"These results indicate that climate tipping is an imminent risk in the Earth System. Even the safe operating space of 1.5 or 2.0 degrees above present generally assumed by the IPCC might not be all that safe. According to the precautionary principle, we must consider abrupt and irreversible changes to the climate system as a real risk - at least until we understand these phenomena better," says Professor Michael Ghil.

The TiPES project is an EU Horizon 2020 interdisciplinary climate science project on tipping points in the Earth system. 18 partner institutions work together in more than 10 countries. TiPES is coordinated and led by The Niels Bohr Institute at the University of Copenhagen, Denmark and the Potsdam Institute for Climate Impact Research, Germany.

The TiPES project has received funding from the European Horizon 2020 research and innovation program, grant agreement number 820970.

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This news release is about two studies.

1) Pierini, S., and M. Ghil, 2021: Climate tipping points induced by parameter drift: an excitable system study, Scientific Reports, 11, 11126, doi:10.1038/s41598-021-90138-1, https://rdcu.be/clp5V.

AND

2) Vannitsem, S., J. Demaeyer, and M. Ghil, 2021: Extratropical low-frequency variability with ENSO forcing: A reduced-order coupled model study, Journal of Advances in Modeling Earth Systems, 13, e2021MS002530, doi:10.1029/2021MS002530.

 

Loss of biodiversity in streams threatens vital biological process

PENN STATE

Research News

IMAGE: THE PHOTOGRAPHS OF AQUATIC DETRITIVORES IN THIS GRAPHIC REPRESENT A SUBSET OF FAMILIES (ORDERED LEFT TO RIGHT FROM THE MOST TO THE LEAST ABUNDANT IN THE STUDY). ALL OVER THE... view more 

CREDIT: BRADLEY CARDINALE LAB, PENN STATE

UNIVERSITY PARK, Pa. -- The fast-moving decline and extinction of many species of detritivores -- organisms that break down and remove dead plant and animal matter -- may have dire consequences, an international team of scientists suggests in a new study.

The researchers observed a close relationship between detritivore diversity and plant litter decomposition in streams, noting that decomposition was highest in waters with the most species of detritivores -- including aquatic insects such as stoneflies, caddisflies, mayflies and craneflies, and crustaceans such as scuds and freshwater shrimp and crabs.

Decomposition is a biological process that's vital to life, explained study co-author Bradley Cardinale, professor and head of the Department of Ecosystem Science and Management, College of Agricultural Sciences, Penn State.

"The plant matter that doesn't get eaten by animals ultimately dies and must be recycled so that biologically essential nutrients are rereleased into the environment where they can be used again by plants," he said. "If that process of decomposition doesn't occur, or slows significantly, then life comes to a screeching halt. Phosphorus, nitrogen and other nutrients that we need as humans don't even exist in a biologically available form unless they get decomposed and recycled."

But all over the world, detritivore populations are dwindling and disappearing at an alarming rate -- a grim reality that spurred the study. There is good evidence that the rate of extinction for these organisms is 1,000 to 10,000 times faster than has occurred through the historic record, Cardinale pointed out.

"There has been a huge question about whether or not the diversity of these aquatic insects and crustaceans is crucial," Cardinale said. "If they go extinct, is this biological process of decomposition going to slow or not? We didn't have a good answer prior to this study. We didn't know if the extinction of these animals will greatly affect the ability of ecosystems to sustain life, or if other organisms such as bacteria and fungi will fill the ecological niche and accomplish a similar level of decomposition."

There are a number of causes of extinction, Cardinale said. In order of importance, they are habitat loss, overharvesting (which doesn't apply to this study), competition from invasive species, disease, pollution and climate change -- which he called "the big unknown at this point."

The study was global and uncommonly robust, involving 75 scientists analyzing decomposition in 38 headwater streams that were similar in size, depth and physical habitat across 23 countries on six continents. Most of the streams selected by the researchers had rocky substrate and were shaded by dense riparian vegetation.

CAPTION

This map shows the global distribution of study sites in different biomes. Streams were located in tundra, temperate broadleaf forest, temperate coniferous forest, Mediterranean forest, xeric shrubland, tropical wet forest and tropical savanna.

CREDIT

Bradley Cardinale Lab, Penn State

At each site, the researchers incubated identical plant litter mixtures comprised of nine species collected at different locations around the world and distributed among study partners. Litter mixtures were enclosed within paired coarse-mesh and fine-mesh litterbags containing the same amount and type of litter.

"The two types of litterbags allowed us to quantify the amount of decomposition done by detritivores and by microbial organisms in the streams," Cardinale said. "We saw that in the litter enclosed by fine mesh bags that couldn't be accessed by aquatic insects or crustaceans, much less decomposition took place."

That indicates that bacteria and fungi alone likely can't accomplish the amount of decomposition needed in stream ecosystems, he added.

"When we excluded these animals, we saw a huge drop in decomposition rates, which means other organisms didn't compensate for them," Cardinale said. "When the detritivores were excluded, simulating extinction, we lost way more than 50% of the decomposition in the streams."

In findings recently published in Nature Communications, the researchers noted that streams with an abundance of detritivores had the highest rates of decomposition. They reported that the relationship between detritivore diversity and decomposition was stronger in tropical areas than in temperate areas and absent in boreal areas, and that abundance and biomass were important in temperate and boreal areas, but not in tropical areas.

According to the research team, the study results suggest that litter decomposition likely is being altered by detritivore extinctions and that these effects are particularly strong in tropical areas, where detritivore diversity already is relatively low and some environmental stressors are particularly prevalent.

Some of the study results are not surprising, Cardinale suggested. The abundance and size of detritivores are known to have a very strong impact on decomposition. So, streams that have more of them -- or that have larger invertebrates, such as big crabs and shrimp -- have more decomposition.

"But what was a surprise is that we also found that the diversity, the number of different species that were in streams, was one of the most dominant predictors of decomposition," he said. "And between abundance, body size and diversity, we could explain 82% of all of the global variation in decomposition. That means as these animals go extinct, we're going to lose the ability to decompose and recycle biologically essential materials that other organisms require for survival and growth."

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Luz Boyero, research professor with the University of the Basque Country, Spain, was lead author of the study. Cardinale spearheaded the North American portion of the research.

The Basque Government in Spain funded this work

 

The bitumen puzzle

Bitumen surfaces under the microscope

VIENNA UNIVERSITY OF TECHNOLOGY

Research News

 

IMAGE: BITUMEN SURFACE IMAGED WITH DIFFERENT MICROSCOPIC TECHNIQUES: AFM (TOPOGRAPHY IMAGE) AND AFM-IR (CHEMICAL DISTRIBUTION - IR ABSORPTION AT 1262 CM-1). view more 

CREDIT: TU WIEN

While atomic force microscopy and scanning electron microscopy have already provided information on the morphology of bitumen surfaces in the past, for a long time it was not known whether surface and chemical composition correlate with each other. However, the chemical composition of the surface is of particular interest because oxidation processes take place there, triggered by oxygen-containing molecules in the air such as ozone, nitrogen oxides or hydroxyl radicals. The oxidation process accelerates the aging of the material - the bitumen becomes porous and damage develops.

The materials chemists Dr. Ayse Koyun and Prof. Hinrich Grothe from TU Wien therefore examined the bitumen surface using various physicochemical analysis methods and compared the respective results with each other. The researchers published the data on June 29 in the journal Scientific Reports.

A diverse material

Bitumen is produced from petroleum and primarily used for the production of asphalt. Its consistency depends largely on temperature - at hot temperatures it is viscous and larger chemical compounds such as aliphatics, petroleum resins and asphaltenes move freely in the mass. When the bitumen cools, however, the material solidifies and the individual molecules arrange themselves in characteristic patterns. Analyses have already shown that so-called core-shell particles form on the surface. These are composites that consist of at least two different components.

Since asphalt and bitumen are used for road construction as well as for waterproofing work, the longest possible product lifetime is desirable. To slow down the aging of the material, reactions triggered by reactive gases, light and heat must be minimized. " Once we understand the oxidation behavior of bitumen better, we can look for appropriate measures to prevent atmospheric aging. This can extend the lifespan of a bitumen product by many years, saving energy and material resources," Koyun explains. In a study published in Colloids and Surfaces A: Physicochemical and Engineering Aspects, she has already been able to show how the chemical composition of bitumen affects its aging process.

Mix of methods provides new info

In close collaboration with Harvard University, Bruker Nano-Surfaces Division as well as IONTOF GmbH, Ayse Koyun, first author of the study, investigated the bitumen surface using three different methods: nanoscale infrared spectroscopy based on photothermal expansion (AFM-IR), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and fluorescence microscopy. In combination, these methods provide valuable insights into the multiphase nature of the bitumen surface. "The resolution of conventional measurement methods used to study surface composition is too low for chemical characterization. Individual domains of the surface cannot be determined in this way," Koyun explains. "However, by combining different physicochemical methods, we succeed in mapping the structure down to ten nanometers." The result: the surface is heterogeneous. The findings of microscopic and spectroscopic methods correlate and can be interpreted conclusively.

A complete picture is created

"For a long time, bitumen was like an unsolved puzzle for us materials chemists," says Hinrich Grothe, head of the Physical Chemistry of the Atmosphere research group. "We know many details, but until now it has not been possible to piece them together into a complete picture. However, the combination of several physicochemical methods, as we applied them, was finally able to show us how the individual molecular assemblies are distributed in the bitumen." " This allowed us to solve the puzzle and complete our knowledge of bitumen," adds Ayse Koyun, who is completing two research stays at Harvard University as part of a Marshall Scholarship and with support from the TU Wien.

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Wallonia as an international reference for the timeline

Paleontologists from Univeristy of Liège (Belgium) redefine the geological boundary between the Devonian and Carboniferous periods. A Walloon site could be chosen as a world reference for this boundary.

UNIVERSITY OF LIEGE

Research News

 

IMAGE: SHOWING DEFORMATIONS RELATED TO WATER STRESS IN THE PLANTS THAT PRODUCED THEM DURING A GLOBAL COOLING. view more 

CREDIT: PRESTIANNI ET AL., 2016, GEOLOGICA BELGICA

In 2016, researchers from the EDDyLab - Evolution & Diversity Dynamics Lab - at the University of Liège (Belgium) proposed a new definition of the geological boundary between the Devonian and Carboniferous periods (359 million years). This new definition has been tested by hundreds of researchers around the world and the results are now compiled in a special issue of the journal Palaeodiversity & Palaeoenvironments.

Geological time is divided into periods (Cambrian, Carboniferous, Jurassic, etc.), together covering the 4.6 billion year history of the Earth. The many climatic, environmental and biological changes that have punctuated this history are recorded in the rock layers, forming an incredibly rich archive of the Earth's past. "The study of these successive layers allows us to recognise the boundaries between these different periods, each boundary being defined by a specific event or 'marker', such as an extinction event or a change in climate," explains Julien Denayer, a palaeontologist at the EDDyLab and first author of the article. A locality is then designated, making the rocky successions of this particular place the international reference for this transition. "It was in Belgium, in the 19th century, that numerous divisions of the time scale were defined, such as the Frasnian, Tournaisian, Viséian, Namurian, etc... These references are still used today on an international scale.

The boundary between the so-called Devonian and Carboniferous geological periods (359 million years ago) was the first to be formally defined in 1927. The fossils marking the boundary were too rare in the rocks, so this definition was of little use. A second attempt was proposed fifty years later, but was also invalidated by the International Commission of Stratigraphy, the scientific body that establishes and validates the subdivision of geological time, again because of the scarcity of boundary fossils.

For the past ten years or so, palaeontologists and geologists specialising in the Devonian and Carboniferous periods have been working on redefining this boundary," says Cyrille Prestianni, palaeontologist at ULiège and co-author of the article. In 2016, we proposed a new definition, this time based on several contemporary phenomena, well recorded in the rocky successions of Wallonia. "According to the ULiège researchers, the boundary between these two periods is defined by the so-called Hangenberg Sandstone event - an episode of abrupt fall in sea level - which is also marked by a major extinction that decimated typical Devonian ecosystems such as coastal marshes and reefs. In ecological terms, this extinction was greater than the extinction of the dinosaurs at the end of the Cretaceous!

Since then, researchers around the world have tested the applicability of this criterion for defining the boundary. The results of these years of research are now compiled in a special volume of the journal Palaeodiversity & Palaeoenvironments. The EDDy Lab researchers publish an exhaustive review of the geological and palaeontological knowledge of the Devonian-Carboniferous boundary in Wallonia and the surrounding regions. In this publication, the members of the EDDy Lab were able to propose a scenario explaining the ecological and climatic crisis that caused the extinction of the Devonian fauna and flora. Our work is not yet finished," says Julien Denayer, "the next step is to select a new type locality. Several Walloon sites are now being studied using state-of-the-art techniques with a view to being proposed to become the world reference for the Devonian-Carboniferous boundary! »

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