Study reveals salps play outsize role in damping global warming

Jelly plankton blooms can offset as much CO2 as emitted by millions of cars

Peer-Reviewed Publication

VIRGINIA INSTITUTE OF MARINE SCIENCE

 

IMAGE: VIMS PROFESSOR DEBORAH STEINBERG PREPARES TO PROCESS A SAMPLE OF SALPS COLLECTED DURING THE 2018 EXPORTS EXPEDITION TO THE NORTHEASTERN PACIFIC. EACH SALP IS ABOUT THE SIZE OF A KIWI FRUIT. view more 

CREDIT: © JASON GRAFF/OREGON STATE UNIVERSITY

Humans continue to amplify global warming by emitting billions of tons of carbon dioxide into the atmosphere each year. A new study reveals that a distant human relative plays an outsize role in damping the impacts of this greenhouse gas by pumping large amounts of carbon from the ocean surface to the deep sea, where it contributes nothing to current warming.

The study, led by Dr. Deborah Steinberg of William & Mary’s Virginia Institute of Marine Science, appeared in the latest issue of Global Biogeochemical Cycles. It reports on research conducted as part of EXPORTS, a 4-year, multi-institutional field program funded by NASA. Co-authors hail from marine institutes in Maine, Bermuda, California, Newfoundland, British Columbia, and Alaska.

The goal of EXPORTS, for EXport Processes in the Ocean from RemoTe Sensing, is to combine shipboard and satellite observations to more accurately quantify the global impact of the “biological pump.” This is a suite of biological processes that transport carbon and other organic matter from sunlit surface waters to the deep sea, effectively removing carbon dioxide from the surface ocean and atmosphere. Tiny drifting animals called zooplankton play a key role in the pump by eating phytoplankton, which incorporate carbon from carbon dioxide into their tissues during photosynthesis, then exporting that carbon to depth.

During a month-long EXPORTS expedition to the northeast Pacific Ocean in 2018, Steinberg and colleagues chanced upon a large bloom of a poorly studied player in the biological pump: a species of gelatinous zooplankton named Salpa aspera. Like other salps, these “jelly barrels” begin life with a notochord—the structure that develops into the spinal cord in humans and other vertebrates—and as adults drift through the world’s oceans like tiny transparent whales, filtering microscopic plants afloat in the water. 

Three features keyed the team’s interest in salps, and S. aspera in particular. One is that these organisms can reproduce asexually, rapidly cloning into immense blooms under the right conditions. Second is that S. aspera is bigger and filters more water than most other zooplankton, thus producing larger, heavier fecal pellets. Third is that it migrates up and down through the water each day, rising to feed on phytoplankton during the cover of night and jetting to the perpetual darkness of the deep sea during sunlit hours to avoid its own predators, which include sea turtles, marine birds, and fishes.

Together, these features had led researchers to suspect that salps might play an important role in the biological pump, as large blooms of these relatively bulky zooplankton could effectively transport carbon to depth through their heavy, fast-sinking fecal pellets; vertical migrations that give those pellets a head start on their journey to depth; and the sinking of countless salp carcasses during a bloom (individual salps live only a few weeks).

But the proof is in the pudding, and the ephemeral life cycle and uneven distribution of salps has long challenged efforts to study their role in carbon export and deep-sea food webs. “Salps follow a ‘bloom or bust’ life cycle,” says Steinberg, “with populations that are inherently patchy in space and time. That makes it hard to observe or model their contribution to the export of carbon to the deep sea.”

During the 2018 EXPORTS expedition to the Pacific, Steinberg and colleagues were able to overcome these challenges by deploying a wide range of ocean-observation tools, from traditional plankton nets and sediment traps to underwater video recorders and sonar-based computer models. Moreover, by using two research vessels—the 277-ft Roger Revelleand the 238-ft Sally Ride—the scientists were able to observe conditions not only inside the salp bloom but in surrounding waters, providing a broader geographic context for their study.

The results of the team’s unprecedented field campaign were clear. “High salp abundances, combined with unique features of their ecology and physiology, lead to an outsized role in the biological pump,” says Steinberg. 

To put things in perspective, the observed salp bloom covered more than 4,000 square miles (~11,000 km2), about the size of Connecticut. With onboard experiments showing salps capable of exporting a daily average of 9 milligrams of carbon through each square meter at 100 meters below the bloom, the amount of carbon exported to the deep sea was about 100 metric tons per day. For comparison, a typical passenger car emits 4.6 metric tons per year. Comparing these values shows the carbon removed from the climate system each day of the bloom is equal to taking 7,500 cars off the road. Adjusting these values using the team’s highest measured rate of salp-mediated export (34 mg of C per day) increases the carbon offset to more than 28,000 vehicles.

Moving forward, the team calls for increased recognition of the key role that salps play in global carbon export. “Blooms like the one we observed often go undetected,” says Steinberg, “and their contributions to the biological pump are rarely quantified, even in some of the best-studied regions of the world's oceans.” Incorporation of salp dynamics into a recent carbon-cycle model illustrates the potential of salp-mediated export. In this global model, salps and other tunicates exported 700 million metric tons of carbon to the deep sea each year, equal to emissions from more than 150 million cars. 

“Greater use of new technologies, such as adding video imaging systems to autonomous floats, would help detect these salp blooms,” says Steinberg. “Our study serves as a ‘call to arms’ to better detect and quantify these processes, using technology and sampling schemes that enable their inclusion in measurements and models of the biological carbon pump.”

A snorkeler swims through a salp bloom off the coast of New Zealand. Salps resemble jellyfish but are more closely related to humans. VIMS-led research reveals they play an outsized role in the ocean’s biological carbon pump.

CREDIT

Paul Caiger

JOURNAL

Global Biogeochemical Cycles

DOI

10.1029/2022GB007523 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

The outsized role of salps in carbon export in the subarctic Northeast Pacific Ocean

Study details timing of past glacier advances in Northern Antarctic Peninsula

Peer-Reviewed Publication

UNIVERSITY OF WYOMING

 

IMAGE: THIS LANDSCAPE SCENE ON CAPE RASMUSSEN SHOWS WHERE THE GLACIER ICE RECEDED AND EXPOSED BLACK MOSS. view more 

CREDIT: DEREK FORD

Receding glaciers in the northern Antarctic Peninsula are uncovering and reexposing black moss that provides radiocarbon kill dates for the vegetation, a key clue to understanding the timing of past glacier advances in that region.

A University of Wyoming researcher led a study that determined the black moss kill dates coincide with evidence of glacier advances from other studies that found such events occurred 1,300, 800 and 200 calibrated years prior to 1950.

“We used radiocarbon ages, or kill dates, of previously ice-entombed dead black mosses to reveal that glaciers advanced during three distinct phases in the northern Antarctic Peninsula over the past 1,500 years,” says Dulcinea Groff, a postdoctoral research associate in the UW Department of Geology and Geophysics.

Groff was lead author of a paper titled “Kill dates from re-exposed black mosses constrain past glacier advances in the northern Antarctic Peninsula” that appeared Jan. 20 in Geology, a journal that publishes timely, innovative and provocative articles relevant to its international audience, representing research from all fields of the geosciences. 

Researchers from Lehigh University, the University of Hawaii-Manoa, and Northeast Normal University and the Chinese Academy of Sciences, both in Changchun, in the Jiln Province of China, contributed to the paper.

Mosses are one of the few types of plants living in Antarctica and can become overridden and killed by advancing glaciers. The timing of when the glaciers killed the moss provides an archive of glacier history, Groff says.

For example, when glaciers expand or advance, they can entomb or cover the plant. This starves the plant of light and warmth. The date the plant died is the same time the glacier advanced over that location.

“As glaciers recede, these previously entombed mosses are exposed and are dead and black,” Groff explains. “What’s so valuable about these kill dates compared to other records -- like the ages of glacial erratics or penguin remains -- is their accuracy. They provide a clearer picture of the climate history owing to their direct carbon exchange with the atmosphere and decreased error around the age estimate.”

Glacial erratics are glacially deposited rock that differs from native rock to a specific area.

The terrestrial cryosphere and biosphere of the Antarctic Peninsula are changing rapidly as “first responders” to polar warming, Groff says.

“We know, from other studies, that large glaciers of the Antarctic Peninsula are responding quickly to warmer summer air temperatures, and scientists have modeled that the glaciers expanded in the past because of cooler temperatures, and not increased precipitation,” Groff says. “However, we know much less about how this plays out at sea level where ice, ocean and sensitive coastal life interact. Knowing when glaciers advanced and retreated in the past would improve our understanding of biodiverse coastal ecosystems -- thriving with seals, penguins and plants -- and their sensitivity in the Antarctic Peninsula.”

Groff says one of the limitations of reconstructing glacier history is that there are few types of terrestrial archives that can be used to constrain past glacier behavior. Dead plants that have been reexposed, abandoned penguin colonies and rocks can be dated to better know the timing of permanent snow or glacier advance in the past.

During the summers of 2019 and 2020, the research field team, which included Groff, collected black mosses from Robert Island, Anvers Island, Charles Point and Cape Rasmussen, according to the paper. The group inspected and cleaned 39 black moss samples.

“We collected black mosses around the northern Antarctic Peninsula by exploring the edges of glaciers and nunataks at several locations. By radiocarbon dating the mosses, we found that glaciers advanced three times in the past 1,500 years,” Groff says. “This is evidence for phases of cooler and potentially wetter conditions than today.”

On Anvers Island, Groff says the group learned that the last time the glacier was at its 2019 position was around 850 years ago as it expanded over the course of several centuries.

“Our estimates of glacier advance are much slower than recent retreat,” she says. “Interestingly, we found that the glacier front with the fastest advance also had the fastest retreat, suggesting that hotspots of rapid coastal glacier dynamics occur in the Antarctic Peninsula.”

Groff says the dataset her research group has compiled is unique, citing it’s rare to have past net advance rates in the literature because glacial records tend to be destroyed when the glacier advances. Thus, these black mosses can reliably be used to estimate glacier advances in the past.

“There are other lines of evidence that support our moss kill dates for past cooler conditions such as peat records indicating lower biological productivity, as well as evidence for sea-level change from raised beaches as a result of changing ice mass,” she says. “It’s also possible that the climate conditions that led to glacier advances involved wetter conditions and would have had a negative impact on penguins, as we know they do today. Many of the recent abandoned penguin colonies are the same age as our youngest black moss.”

The National Science Foundation funded the research.

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JOURNAL

Geology

DOI

10.1130/G50314.1 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Kill dates from re-exposed black mosses constrain past glacier advances in the northern Antarctic Peninsula

Discovery of new ice may change understanding of water

Researchers at UCL (University College London) have discovered a new type of ice that more closely resembles liquid water than any other known ices and that may rewrite our understanding of water and its many anomalies

Peer-Reviewed Publication

UNIVERSITY COLLEGE LONDON

 

IMAGE: PART OF THE SET-UP FOR CREATING MEDIUM-DENSITY AMORPHOUS ICE view more 

CREDIT: CHRISTOPH SALZMANN

Researchers at UCL and the University of Cambridge have discovered a new type of ice that more closely resembles liquid water than any other known ices and that may rewrite our understanding of water and its many anomalies.

The newly discovered ice is amorphous - that is, its molecules are in a disorganised form, not neatly ordered as they are in ordinary, crystalline ice. Amorphous ice, although rare on Earth, is the main type of ice found in space. That is because in the colder environment of space, ice does not have enough thermal energy to form crystals.

For the study, published in the journal Science, the research team used a process called ball milling, vigorously shaking ordinary ice together with steel balls in a jar cooled to -200 degrees Centigrade.

They found that, rather than ending up with small bits of ordinary ice, the process yielded a novel amorphous form of ice that, unlike all other known ices, had the same density as liquid water and whose state resembled water in solid form. They named the new ice medium-density amorphous ice (MDA).

The team suggested that MDA (which looks like a fine white powder) may exist inside ice moons of the outer solar system, as tidal forces from gas giants such as Jupiter and Saturn may exert similar shear forces on ordinary ice as those created by ball milling. In addition, the team found that when MDA was warmed up and recrystallised, it released an extraordinary amount of heat, meaning it could trigger tectonic motions and “icequakes” in the kilometres-thick covering of ice on moons such as Ganymede.

Senior author Professor Christoph Salzmann (UCL Chemistry) said: “Water is the foundation of all life. Our existence depends on it, we launch space missions searching for it, yet from a scientific point of view it is poorly understood.

“We know of 20 crystalline forms of ice, but only two main types of amorphous ice have previously been discovered, known as high-density and low-density amorphous ices. There is a huge density gap between them and the accepted wisdom has been that no ice exists within that density gap. Our study shows that the density of MDA is precisely within this density gap and this finding may have far-reaching consequences for our understanding of liquid water and its many anomalies.”

The density gap between the known amorphous ices has led scientists to suggest water in fact exists as two liquids at very cold temperatures and that theoretically, at a certain temperature, both of these liquids could co-exist, with one type floating above the other, as when mixing oil and water. This hypothesis has been demonstrated in a computer simulation, but not confirmed by experiment. The researchers say that their new study may raise questions about the validity of this idea.

Professor Salzmann said: “Existing models of water should be re-tested. They need to be able to explain the existence of medium-density amorphous ice. This could be the starting point for finally explaining liquid water.”

The researchers proposed that the newly discovered ice may be the true glassy state of liquid water – that is, a precise replica of liquid water in solid form, in the same way that glass in windows is the solid form of liquid silicon dioxide. However, another scenario is that MDA is not glassy at all, but is in a heavily sheared crystalline state.

Co-author Professor Andrea Sella (UCL Chemistry) said: “We have shown it is possible to create what looks like a stop-motion kind of water. This is an unexpected and quite amazing finding.”

Lead author Dr Alexander Rosu-Finsen, who carried out the experimental work while at UCL Chemistry, said: “We shook the ice like crazy for a long time and destroyed the crystal structure. Rather than ending up with smaller pieces of ice, we realised that we had come up with an entirely new kind of thing, with some remarkable properties.”

By mimicking the ball-milling procedure via repeated random shearing of crystalline ice, the team also created a computational model of MDA. Dr Michael Davies, who carried out the computational modelling whilst a PhD student in the ICE (interfaces, catalytic & environmental) lab at UCL and the University of Cambridge, said: “Our discovery of MDA raises many questions on the nature of liquid water and so understanding MDA’s precise atomic structure is very important.”

Water has many anomalies that have long baffled scientists. For instance, water is at its most dense at 4 degrees Centigrade and becomes less dense as it freezes (hence ice floats). Also, the more you squeeze liquid water, the easier it gets to compress, deviating from principles true for most other substances. 

Amorphous ice was first discovered in its low-density form in the 1930s when scientists condensed water vapour on a metal surface cooled to -110 degrees Centigrade. Its high-density state was discovered in the 1980s when ordinary ice was compressed at nearly -200 degrees Centigrade. While common in space, on Earth, amorphous ice is thought only to occur in the cold upper reaches of the atmosphere.

Ball milling is a technique used in several industries to grind or blend materials, but had not before been applied to ice. In the study, liquid nitrogen was used to cool a grinding jar to -200 degrees Centigrade and the density of the ball-milled ice was determined from its buoyancy in liquid nitrogen. The researchers used a number of other techniques to analyse the structure and properties of MDA, including X-ray diffraction (looking at the pattern of X-rays reflected off the ice) and Raman spectroscopy (looking at how the ice scatters light) at UCL Chemistry as well as small-angle diffraction at the UCL Centre for Nature Inspired Engineering to explore its long-range structure. They also successfully replicated the process of producing medium-density ice in a computer simulation, using the UCL Kathleen High Performance Computing Facility.

Furthermore, they used calorimetry to investigate the heat released when the medium-density ice recrystallised at warmer temperatures. They found that, if they compressed the MDA and then warmed it up, it released a surprisingly large amount of energy as it recrystallised showing that H2O can be a high-energy geophysical material that may drive tectonic motions in the ice moons of the solar system.

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JOURNAL

Science

DOI

10.1126/science.abq2105 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Medium-density amorphous ice

ARTICLE PUBLICATION DATE

2-Feb-2023

New form of “medium-density” 

amorphous ice discovered, formed 

through ball milling

Peer-Reviewed Publication

AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (AAAS)

Ball milling “ordinary” ice at low temperatures – a process that involves vigorously shaking a cryogenically-cooled container full of ice and steel balls – creates a previously unrecognized amorphous form with a density close to liquid water, researchers report. The finding suggests that water is more complex at low temperatures than previously recognized, which not only has implications for our understanding of water and its curious, unexplained anomalies, but also for our understanding of how water exists and functions throughout the universe. Frozen water can take many forms. There are 20 known common or crystalline phases of water ice and at least two families of amorphous form. Unlike common ice, whose molecules are regularly arranged in a hexagonal lattice, amorphous forms lack a highly ordered crystalline structure. Although almost all frozen water on Earth exists as crystalline ice, amorphous ice is likely the most common structure for water in the universe at large. In general, amorphous ices are distinguished by their densities, with low-density amorphous ice having a density of 0.94 g/cm3 and high-density amorphous ice forms, which start at 1.13 g/cm3. However, neither crystalline nor amorphous ices have a form with a density near that of liquid water (~1 g/cm3). This density gap is a cornerstone of our current understanding of water. Alexander Rosu-Finsen and colleagues now show that ball milling common ice at nearly -200 degrees Celsius (77 Kelvin) leads to a “medium-density” form of amorphous ice (MDA) with a density of 1.06 ± 0.06 g/cm3. Ball milling has been used to create other amorphous materials, like metallic alloys and inorganic compounds, but had not previously been applied to ice. Using a variety of experimental techniques and computational simulation, Rosu-Finsen et al. evaluated and characterized the nature of this new form of ice, revealing its distinct structure and unique mechanical properties. According to the authors, the findings open interesting new questions into the structural nature of MDA, including whether or not it represents the true glassy state of liquid water.

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JOURNAL

Science

DOI

10.1126/science.abq2105 

ARTICLE TITLE

Medium-density amorphous ice

ARTICLE PUBLICATION DATE

3-Feb-2023

Ice cores show even dormant volcanoes leak abundant sulfur into the atmosphere

Peer-Reviewed Publication

UNIVERSITY OF WASHINGTON

 

IMAGE: THESE SULFUROUS PLUMES IN LAUGAVEGUR, ICELAND, ARE NOT RECORDED BY SATELLITE OBSERVATIONS. ICE CORE ANALYSIS SHOWS THAT SUCH PLUMES HAVE A MUCH LARGER EFFECT ON THE LEVEL OF AEROSOLS IN THE ATMOSPHERE THAN PREVIOUSLY BELIEVED. view more 

CREDIT: URSULA JONGEBLOED/UNIVERSITY OF WASHINGTON

Volcanoes draw plenty of attention when they erupt. But new research led by the University of Washington shows that volcanoes leak a surprisingly high amount of their atmosphere- and climate-changing gases in their quiet phases. A Greenland ice core shows that volcanoes quietly release at least three times as much sulfur into the Arctic atmosphere than estimated by current climate models.

The study, led by the University of Washington and published Jan. 2 in Geophysical Research Letters, has implications for better understanding Earth’s atmosphere and its relationship with climate and air quality.

“We found that on longer timescales the amount of sulfate aerosols released during passive degassing is much higher than during eruptions,” said first author Ursula Jongebloed, a UW doctoral student in atmospheric sciences. “Passive degassing releases at least 10 times more sulfur into the atmosphere, on decadal timescales, than eruptions, and it could be as much as 30 times more.”

The international team analyzed layers of an ice core from central Greenland to calculate levels of sulfate aerosols between the years 1200 and 1850. The authors wanted to look at the sulfur emitted by marine phytoplankton, which were previously believed to be the biggest source of atmospheric sulfate in pre-industrial times.

“We don’t know what the natural, pristine atmosphere looks like, in terms of aerosols,” said senior author Becky Alexander, a UW professor of atmospheric sciences. “Knowing that is a first step to better understanding how humans have influenced our atmosphere.”

The team deliberately avoided any major volcanic eruptions and focused on the pre-industrial period, when it’s easier to distinguish the volcanic and marine sources.

“We were planning to calculate the amount of sulfate coming out of volcanoes, subtract it and move on to study marine phytoplankton,” Jongebloed said. “But when I first calculated the amount from volcanoes, we decided that we needed to stop and address that.”

The location of the ice core at the center of the Greenland Ice Sheet records emissions from sources over a wide swath of North America, Europe and surrounding oceans. While this result applies only to geologic sources within that area, including volcanoes in Iceland, the authors expect it would apply elsewhere.

“Our results suggest that volcanoes, even in the absence of major eruptions, are twice as important as marine phytoplankton,” Jongebloed said.

The discovery that non-erupting volcanoes leak sulfur at up to 3 times the rate previously believed is important for efforts to model past, present and future climate. Aerosol particles, whether from volcanoes, vehicle tailpipes or factory chimneys, block some solar energy. If the natural levels of aerosols are higher, that means the rise and fall of human emissions — peaking with the acid rain of the 1970s and then dropping with the Clean Air Act and increasingly strict air quality standards — have had less of an effect on temperature than previously believed.

“There’s sort of a ‘diminishing returns’ effect of sulfate aerosols, the more that you have, the less the effect of additional sulfates,” Jongebloed said. “When we increase volcanic emissions, which increases the baseline of sulfate aerosols, we decrease the effect that the human-made aerosols have on the climate by up to a factor of two.”

That means Arctic warming in recent decades is showing more the full effects of rising heat-trapping greenhouse gases, which is by far the main control on Earth’s average temperature.

“It’s not good news or bad news for climate,” Jongebloed said of the result. “But if we want to understand how much the climate will warm in the future, it helps to have better estimates for aerosols.”

Better estimates for aerosols can improve global climate models.

“We think that the missing emissions from volcanoes are from hydrogen sulfide,” said Alexander, referring to the gas that smells like rotten eggs. “We think that the best ways to improve these estimates of volcanic emissions is to really think about the hydrogen sulfide emissions.”

The study was funded by the U.S. National Science Foundation, NASA and the National Natural Science Foundation of China. Other UW co-authors are undergraduate students Sara Salimi and Shana Edouard, doctoral student Shuting Zhai, research scientist Andrew Schauer, and professor Robert Wood. Other co-authors are Lei Geng, a former UW postdoctoral researcher now at the University of Science and Technology of China; Jihong Cole-Dai and Carleigh Larrick at South Dakota State University; Tobias Fischer at the University of New Mexico; and Simon Carn at Michigan Technological University.

This plume escaping from a lake near the summit of Oregon’s Mount Hood, seen in May 2021, is not captured by satellite observations. Ice core analysis shows that such plumes have a much larger effect on the level of aerosols in the atmosphere than previously believed.

CREDIT

Ursula Jongebloed/University of Washington

For more information, contact Jongebloed at ujongebl@uw.edu or Alexander at beckya@uw.edu.

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JOURNAL

Geophysical Research Letters

DOI

10.1029/2022GL102061 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Underestimated Passive Volcanic Sulfur Degassing Implies Overestimated Anthropogenic Aerosol Forcing

Researchers: Energy-efficient construction materials work better in colder climates

The researchers from Lithuania and Cyprus claim that the energy payback period of using phase change materials, new technology in the construction industry, is the shortest in a colder climate.

Peer-Reviewed Publication

KAUNAS UNIVERSITY OF TECHNOLOGY

 

IMAGE: DR EGLE KLUMBYTE, A RESEARCHER AT KTU FACULTY OF CIVIL ENGINEERING AND ARCHITECTURE view more 

CREDIT: KTU

The researchers from Lithuania and Cyprus claim that the energy payback period of using phase change materials, new technology in the construction industry, is the shortest in a colder climate. The optimal location for their usage is the interior on the northern side of the building. The study provides informed answers regarding the application of PCMs to improve buildings’ energy efficiency.

In recent years, phase change materials (PCMs) used to improve the energy efficiency of buildings are gaining momentum. PCMs can store and release large amounts of energy – when in a solid phase, they can absorb heat, providing a cooling effect and when a PCM is in its liquid phase it can release heat, providing a warming effect.

“The ice melting to water is a phase change material, as is butter melting to oil. Why is it special? When material changes phase, it also absorbs and releases energy. In construction, these materials are encapsulated, i.e. the micro PCM capsules are integrated into a building element, such as concrete,” explains Paris Fokaides, a principal investigator at Kaunas University of Technology (KTU), Lithuania.

Together with colleagues from Frederick University in Cyprus, KTU researchers were conducting a study in different European regions aiming to calculate the efficiency of the application of PCMs for the energy upgrade of the existing buildings. Their research revealed that the efficiency and energy payback period of PCM depends on certain conditions, such as the geographical location and the wall orientation of the building.

“The thermal performance assessment of existing buildings is highly valuable information, which can be useful when making renovation decisions,” says Eglė Klumbytė, a researcher at KTU Faculty of Civil Engineering and Architecture, a co-author of the study.

According to her, it is important to understand how and where to use the appropriate materials for maximum efficiency.

In cold climates, the investments pay off in less than a year

The work examines the application of PCM coatings in diverse meteorological conditions in Europe, for all major buildings’ orientations. In total, 16 numerical simulations were carried out for the four calendar months of January, April, July and October and for three latitudes of Athens, Milan and Copenhagen.

“We wanted our research results to be globally applicable, that’s why we chose the locations with typical climatic conditions in Southern, Central and Northern Europe,” says Fokaides.

The first 8 numerical simulations were performed with phase change material integrated into the building element structure and the other 8 simulations – in the absence of PCM. The PCM thickness incorporated was 4 cm. The annual energy saving was calculated for four typical months, representing the four seasons of the year (winter, spring, summer, and autumn).

“One of the main study outcomes highlighted the fact that PCM performed better under cold conditions,” says Klumbytė.

According to the researchers, this makes perfect sense – firstly, in colder conditions, PCM absorbs more energy, and secondly, since in colder climates the buildings use more energy (electricity, heating, etc.) the energy saving in these conditions is more efficient.

“In the study, we have developed the energy payback period concept, which means the balance between the energy used to produce these materials and gained while using them. Energy payback period indicates how long it will take for the energy that is saved in the PCMs to eliminate the energy costs of their production,” explains Fokaides.

The study revealed that PCM implementation can contribute to energy savings in certain cases, varying from 0.24 up to 29,84 kWh/m2a and energy payback periods from less than a year to almost 20 years. The longest energy payback period was calculated in warmer climates, and the shortest – in colder locations. The optimal orientation for placing PCMs is west and east in Athens, east and north in Milan, and north in Copenhagen. Also, PCMs work best when they are integrated into interior structures.

Researched topics never discussed before

“The developed numerical model demonstrates the ability to carry out a thermal assessment under diverse conditions with accurate results. The main goal of the European Union is sustainable environmental development. Our study can greatly contribute towards achieving this goal,” Klumbytė is convinced.

According to Fokaides, the above-described study is researching topics that have not been discussed in scientific literature before. The optimal location of the phase change material in the building, its optimal orientation and the energy payback period are entirely new concepts in the broad theme of the energy performance of the built environment.

“However, being a Greek, I cannot overlook the fact that the first description of an eco-friendly building was written by Socrates 2.5 thousand years ago. Back then, he indicated that the northern wall of a building needs to be thicker compared to the southern, thus our idea that wall orientation is crucial when considering its structural composition is related to that of Socrates,” says a KTU researcher.

The KTU researchers claim that the methodology and dataset provided in this work can be used for further development of the buildings’ thermal assessment tools. Currently, the team is starting a new 1.5 million worth research project, which will focus on the digitalisation of the findings. This could include developing smart sensors to measure building elements’ thermal performance in real-time and other aspects. According to scientists, this topic has vast potential for commercialisation.

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JOURNAL

Construction and Building Materials

DOI

10.1016/j.conbuildmat.2022.129984 

METHOD OF RESEARCH

Computational simulation/modeling

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Numerical and environmental analysis of post constructive application of PCM coatings for the improvement of the energy performance of building structures

Water crises due to climate change: more severe than previously thought

The interference of climate change with the planet's water cycle is a well established fact. New analyses suggest that in many places, runoff responds more sensitively than previously assumed.

Peer-Reviewed Publication

VIENNA UNIVERSITY OF TECHNOLOGY

Climate change alters the global atmospheric circulation, which in turn alters precipitation and evaporation in large parts of the world and, in consequence, the amount of river water that can be used locally. So far, projections of climate impact on stream flow have usually been calculated on the basis of physical models, e.g. the projections reported by IPCC (Intergovernmental Panel on Climate Change).

However, new data analyses conducted under the leadership of Prof. Günter Blöschl (TU Wien, Vienna) indicate that previous models systematically underestimate how sensitively water availability reacts to certain changing climate parameters. An analysis of measurement data from over 9,500 hydrological catchments from all over the world shows that climate change can lead to local water crises to an even greater extent than previously expected. The results have now been published in the scientific journal Nature Water.

Model approach and measured data approach

"In the climatology community, the effects of climate change on the atmosphere are very well understood. However, their local consequences on rivers and the availability of water falls into the field of hydrology," explains Prof. Günter Blöschl from the Institute of Hydraulic Engineering and Water Resources Management at TU Wien.

Locally, it is often possible to explain very well how water availability is related to external parameters such as precipitation or temperature - this is being studied at many measuring stations around the world, in particular in Blöschl's hydrology laboratory in Petzenkirchen, where numerous sensors have been installed over an area of 60 hectares. But global conclusions cannot be drawn from such individual observations: "How the water balance depends on external parameters varies from place to place; local vegetation also plays a very important role here," says Günter Blöschl. It is difficult to develop a simple physical model that can be used to calculate these interrelationships at all places in the world with precision.

Günter Blöschl therefore has collaborated with colleagues from China, Australia, the USA and Saudi Arabia to build up and analyse a large database of streamflow observations from all over the world. Over 9,500 catchments were included, with time series extending several decades into the past.

The water system reacts to climate change more sensitively than thought

"So we don't base our analysis on physical models, but on actual measurements," Günter Blöschl emphasises. "We look at how much the amount of available water changed in the past when external conditions changed. In this way we can find out how sensitively changes in climate parameters are related to a change in local water availability. And this allows us to make predictions for a future, warmer climate."

And it turned out that the connection between precipitation and the amount of water in the rivers is much more sensitive than was previously thought - and thus much more sensitive than is assumed in the models currently used to predict climate change.

Forecasting models of the effects of climate change on water supply should therefore be fundamentally revised. "Up to now, runoff measurements have usually not been included at all in the models, such as those currently reported by the IPCC," says Günter Blöschl. "With the series of measurements now available, it should now be possible to adjust the physical prediction models accordingly."

More severe than assumed

In any case, the results of the research team around Günter Blöschl show that the danger of climate change on the water supply in many parts of the world may have been underestimated so far. Especially for Africa, Australia and North America, the new data predict a significantly higher risk of water supply crises by 2050 than previously assumed.

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JOURNAL

Nature Water

DOI

10.1038/s44221-023-00030-7 

METHOD OF RESEARCH

Meta-analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Future global streamflow declines are probably more severe than previously estimated

ARTICLE PUBLICATION DATE

2-Feb-2023

An ultra-stable protein nanowire made by bacteria provides clues to combating climate change

Peer-Reviewed Publication

YALE UNIVERSITY

 

IMAGE: . “NANOWIRES” PRODUCED BY GEOBACTER IN RESPONSE TO AN ELECTRIC FIELD APPLIED TO ELECTRICITY-PRODUCING BIOFILMS. THESE NANOWIRES ARE COMPOSED OF CYTOCHROME OMCZ AND SHOW 1000-FOLD HIGHER CONDUCTIVITY AND 3-TIMES HIGHER STIFFNESS THAN THE NANOWIRES OF CYTOCHROME OMCS IMPORTANT IN NATURAL ENVIRONMENTS, ALLOWING BACTERIA TO TRANSPORT ELECTRONS OVER 100-TIMES THEIR SIZE. view more 

CREDIT: IMAGE CREDIT: SIBEL EBRU YALCIN. DESIGN: ELLA MARU STUDIO

Accelerated climate change is a major and acute threat to life on Earth. Rising temperatures are caused  atmospheric methane which is 30-times more potent than CO2 at trapping heat. Microbes are responsible for generating half of this methane and elevated temperatures are also accelerating microbial growth and thus producing more greenhouse gases than can be used by plants, thus weakening the earth’s ability to function as a carbon sink and further raising the global temperature.

A potential solution to this vicious circle could be another kind of microbes that eat up to 80% of methane flux from ocean sediments that protects the Earth. How microbes serve as both the biggest producers as well as consumers of methane has remained a mystery because they are very difficult to study in the laboratory. In Nature Microbiology, surprising wire-like properties of a protein highly similar to the protein used by methane-eating microbes, is reported by Yale team led by Yangqi Gu, and Nikhil Malvankar, of Molecular Biophysics and Biochemistry at Microbial Sciences Institute.

The team had previously shown that this protein nanowire shows the highest conductivity known to date,  allowing generation of highest electric power by any bacteria. But to date, no one had discovered how bacteria make them and why they show such extremely high conductivity.

Using cryo-electron microscopy, Yangqi and the team were able to see the nanowire’s atomic structure and discover that hemes packed closely to move electrons very fast with ultra-high stability. It also explains how these bacteria can survive without oxygen-like membrane-ingestible molecules and form communities that can send electrons over 100-times bacterial size. Yangqi and the team also built nanowires synthetically to explain how bacteria make nanowires on demand.

“We are using these heme wires to generate electricity and to combat climate change by understanding how methane-eating microbes use similar heme wires” Malvankar said.

Other authors are Malvankar Lab Members Matthew Guberman-Pfeffer, Vishok Srikanth, Cong Shen, Yuri Londer, Fadel Samatey with collaborators Prof. Victor Batista, Prof. Kallol Gupta, and Fabian Giska.

More details on Behind the Paper in Nature Microbiology community.

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JOURNAL

Nature Microbiology

DOI

10.1038/s41564-022-01315-5 

ARTICLE TITLE

Structure of Geobacter cytochrome OmcZ identifies mechanism of nanowire assembly and conductivity

ARTICLE PUBLICATION DATE

2-Feb-2023

Britain Bans Migrants from Appealing Deportation

World | February 5, 2023, Sunday 

@BBC

The British government is seeking to stop "deportation appeals" for those who reach Britain by crossing the English Channel in small boats, the Times newspaper reports.

The British daily reported that the UK Home Office is working on two options to tackle the problem of illegal migration: either to ban those claiming asylum or to allow them to appeal only after they have been deported.

A Home Office spokesman said the "unacceptable number of people" risking their lives crossing the Channel in small boats was putting "unprecedented strain" on the country's asylum system.

"Our priority is to stop this and prevent illegal crossings and our new Small Boat Operations Command, bolstered by hundreds of extra staff, is working hard to disrupt the business model of people traffickers," the spokesman added.

According to official figures, a record 45,756 migrants crossed the Channel to the UK in 2022.

As well as striking a deal with France to combat people-smuggling in the English Channel, in April last year the UK also unveiled a controversial plan to deport asylum seekers to Rwanda, where their claims will be processed.