It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Tuesday, September 06, 2022
Comprehensive look at health-related topics: Leopoldina Annual Assembly dedicated to global health
The aim of global health is to improve the situation of and equity for the entire global population with respect to health. This requires collaboration among numerous disciplines, as the field of global health comprises not just medical topics but also aspects relating to social, economic, political, and environmental well-being. This broad spectrum of global health issues is at the heart of this year’s Annual Assembly of the German National Academy of Sciences Leopoldina, which will be held in Halle (Saale)/Germany on Friday 23 and Saturday 24 September and online.
Leopoldina Annual Assembly 2022 “Global Health: From Health Services to Climate Change and to Social Justice” Friday 23 September and Saturday 24 September 2022 Leopoldina Main Building Jägerberg 1, 06108 Halle (Saale)/Germany and online
On Friday 23 September, epidemiologist Dr. Mike Ryan, executive director of the World Health Organisation’s (WHO) Health Emergencies Programme, will give the keynote lecture “Health Equity in Times of a Pandemic”. WHO Director General Dr. Tedros Adhanom Ghebreyesus and German Federal Minister of Education and Research Bettina Stark-Watzinger will give a welcome address by video. Minister President of Saxony-Anhalt Dr. Reiner Haseloff will speak in person.
The assembly’s four expert sessions will look at social determinants of health, economic aspects relating to health, health systems research, as well as One Health, which examines the interconnectedness of human, animal, plant, and environmental health. Speakers include Leopoldina members Prof. Dr. Gabriele Stangl, who will examine the pandemic of the overweight (“Globesity”) from the perspective of nutrition, psychologist Prof. Dr. Jürgen Margraf, who will discuss social determinants of mental health, and microbiologist Prof. Dr. Seyed Hasnain, who will talk about India’s experience dealing with the dual challenge posed to health by COVID-19 and tuberculosis.
Expert in veterinary medicine and microbiology and Leopoldina’s Acting Senator of the Section Global Health Prof. Dr. Lothar H. Wieler, as well as Leopoldina members Prof. Dr. Susanne Hartmann, biologist and infection immunologist, and virologist Prof. Dr. Thomas C. Mettenleiter have taken on the scientific coordination of the Annual Assembly, and are also among the speakers. Lothar Wieler will discuss the lessons of the COVID-19 pandemic for global health in the Inaugural Address. Dr. Johanna Hanefeld, Head of the Centre for International Health Protection at the Robert Koch Institute in Berlin, will give a lecture on “International Health Protection and Health Equity” on the evening of Friday 23 September.
The Annual Assembly will take place as a hybrid event. Media representatives who would like to attend the Annual Assembly are kindly asked to send an email to presse@leopoldina.org. They are asked to indicate whether they would like to attend in person or online. Online participation is possible using the video conferencing platform Zoom. The Privacy Policy of Zoom applies while using the video conferencing platform: https://zoom.us/de-de/privacy. Interviews with the speakers can be arranged.
About the German National Academy of Sciences Leopoldina As the German National Academy of Sciences, the Leopoldina provides independent science-based policy advice on matters relevant to society. To this end, the Academy develops interdisciplinary statements based on scientific findings. In these publications, options for action are outlined; making decisions, however, is the responsibility of democratically legitimized politicians. The experts who prepare the statements work in a voluntary and unbiased manner. The Leopoldina represents the German scientific community in the international academy dialogue. This includes advising the annual summits of Heads of State and Government of the G7 and G20 countries. With 1,600 members from more than 30 countries, the Leopoldina combines expertise from almost all research areas. Founded in 1652, it was appointed the National Academy of Sciences of Germany in 2008. The Leopoldina is committed to the common good.
High-accuracy electric vehicle battery monitoring with diamond quantum sensors for driving range extension towards carbon neutrality
The popularity of electric vehicles (EVs) as an environmentally friendly alternative to conventional gasoline vehicles has been on the rise. This has led to research efforts directed towards developing high-efficiency EV batteries. But, a major inefficiency in EVs results from inaccurate estimations of the battery charge. The charge state of an EV battery is measured based on the current output of the battery. This provides an estimate of the remaining driving range of the vehicles.
Typically, the battery currents in EVs can reach hundreds of amperes. However, commercial sensors that can detect such currents cannot measure small changes in the current at milliampere levels. This leads to an ambiguity of around 10% in the battery charge estimation. What this means is that the driving range of EVs could be extended by 10%. This, in turn, would reduce inefficient battery usage.
Fortunately, a team of researchers from Japan, led by Professor Mutsuko Hatano from Tokyo Institute of Technology (Tokyo Tech), has now come up with a solution. In their study published in Scientific Reports, the team has reported a diamond quantum sensor-based detection technique that can estimate the battery charge within 1% accuracy while measuring high currents typical of EVs.
“We developed diamond sensors that are sensitive to milliampere currents and compact enough to be implemented in automobiles. Furthermore, wemeasured currents in a wide range as well as detected milliampere-level currents in a noisy environment,” explains Prof. Hatano.
In their work, the team made a prototype sensor using two diamond quantum sensors that were placed on either side of the busbar (electrical junction for incoming and outgoing currents) in the car. They then used a technique called “differential detection” to eliminate the common noise detected by both the sensors and retain only the actual signal. This, in turn, enabled them to detect a small current of 10 mA amid background environmental noise.
Next, the team used a mixed analog-digital control of the frequencies generated by two microwave generators to trace the magnetic resonance frequencies of the quantum sensor over a bandwidth of 1 gigahertz. This allowed for a large dynamic range (ratio of largest to smallest current detected) of ±1000 A. Moreover, a wide operating temperature range of − 40 to + 85 °C was confirmed to cover general vehicular applications.
Finally, the team tested this prototype for Worldwide Harmonized Light Vehicles Test Cycle (WLTC) driving, a standard test for energy consumption in EVs. The sensor accurately traced the charge/discharge current from -50 A to 130 A and demonstrated the battery charge estimation accuracy within 1%.
What are the implications of these findings? Prof. Hatano remarks, “Increasing battery usage efficiency by 10% would reduce battery weight by 10%, which will reduce 3.5% running energy and 5% production energy of 20 million new EVs in 2030 WW. This, in turn, corresponds to a 0.2% reduction in CO2 emissions in 2030 WW transportation field.”
We certainly hope this breakthrough takes us one step closer to a carbon neutral society!
IMAGE: SLOW SLIDING SPEED (LEFT) LEAVES THE STRUCTUR OF THE METAL INTACT. FAST SLIDING (MIDDLE) COMPLETELY DESTROYS IT. EXTREMELY FAST SLIDING (RIGHT) PARTLY MELTS THE UPPERMOST LAYER, BUT THIS EFFECT PROTECTS THE LAYERS BELOW.view more
CREDIT: TU WIEN
When two metal surfaces slide against each other, a variety of complicated phenomena occur that lead to friction and wear: Small crystalline regions, of which metals are typically composed, can be deformed, twisted or broken, or even fuse together. It is important for industry to understand such effects. After all, wear can destroy machinery and cost a lot of money.
Typically, the faster the two surfaces slide past each other, the greater the wear. But at extremely high speeds, comparable to the muzzle velocity of a firearm, this can be reversed: Above a certain speed, the wear decreases again. This surprising and seemingly contradictory result has now been explained using computer simulations by the Research Unit Tribology at TU Wien and the Austrian Excellence Center for Tribology (AC2T research GmbH) in Wiener Neustadt in cooperation with Imperial College in London.
Simulations on high-performance computers
"In the past, friction and wear could only be studied in experiments," says Stefan Eder (TU Wien, AC2T research GmbH). "Only in recent years have supercomputers become so powerful that we can model the highly complex processes at the material surface on an atomic scale."
Stefan Eder and his team recreate various metal alloys on the computer – not perfect single crystals, with a strictly regular and defect-free arrangement of atoms, but an alloy that is much closer to reality: a geometrically complicated arrangement of tiny crystals that can be offset from each other or twisted in different directions, manifesting as material defects. "This is important because all these defects have a decisive influence on friction and wear," says Stefan Eder. "If we were to simulate a perfect metal on the computer, the result would have little to do with reality."
Surprising results
The research team calculated how the sliding speed affects wear: "At comparatively low speeds, in the order of ten or twenty meters per second, wear is low. Only the outermost layers change, the crystal structures underneath remain largely intact," says Stefan Eder.
If you increase the speed to 80–100 meters per second, the wear increases – that is to be expected, after all, more energy is then transferred into the metal per time unit. "You then gradually enter a range where the metal behaves like a viscous liquid, similar to honey or peanut butter," says Stefan Eder. Deeper layers of the metal are pulled along in the direction of the passing surface, and the microstructure in the metal is completely reorganized. The individual grains that make up the material are twisted, broken, pushed into each other and finally pulled along.
The team experienced a surprise, however, when they moved on to even higher speeds: Above some 300 meters per second – which roughly corresponds to the top speed of aircraft in civil aviation – the wear decreases again. The microstructure of the metal just below the surface, which is completely destroyed at medium speeds, now remains largely intact again.
"This was amazing for us and for the tribology community," says Stefan Eder. "But literature research showed us: this effect has been observed by other scientists in experiments – it is just not very well known because such high speeds rarely occur. However, the origin of this effect has not yet been clarified."
Melting of the surface protects deeper layers
More detailed analyses of the computer data have now shed light on how this effect is possible: At extremely high speeds, friction generates a lot of heat – but in a very uneven way. Only individual patches on the surfaces of the two metals sliding against each other are in contact, and these small areas can reach thousands of degrees Celsius. In between, the temperature is much lower.
As a result, small parts of the surface can melt and then re-crystallize a fraction of a second later. The very outermost layer of the metal is thus dramatically changed, but this is precisely what protects the deeper regions of the material: Only the outermost layers of the material feel the wear, the crystalline structures underneath change only slightly.
"This effect, which has hardly been discussed so far, occurs with different materials," says Stefan Eder. "Wherever friction occurs at high to extremely high speeds, it will be essential to take this into account in the future." This applies, for example, to modern, high-speed bearings and transmissions in E-mobility, or to machines that grind surfaces. The now better-understood effect also plays a role in the stability of metals in a vehicle crash or in the impact of small particles on high-speed aircraft.
Exposure to air pollution in the first six months of life impacts a child’s inner world of gut bacteria, or microbiome, in ways that could increase risk of allergies, obesity and diabetes, and even influence brain development, suggests new CU Boulder research.
The study, published this month in the journal Gut Microbes, is the first to show a link between inhaled pollutants—such as those from traffic, wildfires and industry—and changes in infant microbial health during this critical window of development.
Previous research by the same group found similar results in young adults.
“This study adds to the growing body of literature showing that air pollution exposure, even during infancy, may alter the gut microbiome, with important implications for growth and development,” said senior author Tanya Alderete, assistant professor of Integrative Physiology at CU Boulder.
At birth, an infant hosts little resident bacteria. Over the first two to three years of life, exposure to mother’s milk, solid food, antibiotics and other environmental influences shape which microorganisms take hold. Those microbes, and the metabolites, or byproducts, they produce when they break down food or chemicals in the gut, influence a host of bodily systems that shape appetite, insulin sensitivity, immunity, mood and cognition. While many are beneficial, some microbiome compositions have been associated with Chrohn’s disease, asthma, type 2 diabetes, and other chronic illnesses.
“The microbiome plays a role in nearly every physiological process in the body, and the environment that develops in those first few years of life sticks with you,” said first author Maximilian Bailey, who graduated in May with a master’s in Integrative Physiology and is now a medical student at Stanford University.
Boosting inflammation
For the study, the researchers obtained fecal samples from 103 healthy, primarily breast-fed Latino infants enrolled in the Southern California Mother’s Milk Study and used genetic sequencing to analyze them.
Using their street addresses and data from the U.S. Environmental Protection Agency’s Air Quality System, which records hourly data from monitoring systems, they estimated exposure to PM2.5 and PM10 (fine inhalable particles from things like factories, wildfires and construction sites) and Nitrogen Dioxide (NO2), a gas largely emitted from cars.
“Overall, we saw that ambient air pollution exposure was associated with a more inflammatory gut-microbial profile, which may contribute to a whole host of future adverse health outcomes,” said Alderete.
For instance, infants with the highest exposure to PM2.5 had 60% less Phascolarctobacterium, a beneficial bacterium known to decrease inflammation, support gastrointestinal health and aid in neurodevelopment. Those with the highest exposure to PM10 had 85% more of the microorganism Dialister, which is associated with inflammation.
In a previous study, Alderete found that pregnant Latino women exposed to higher levels of air pollution during pregnancy have babies who grow unusually fast in the first month after birth, putting them at risk for obesity and related diseases later in life.
Infants are particularly vulnerable to the health hazards of air pollution because they breathe faster and their gut microbiome is just taking shape.
“This makes early life a critical window where exposure to air pollution may have disproportionately deleterious health effects,” they write.
Racial minorities at higher risk
Racial minorities and low-income communities, who tend to work, live and attend school in regions closer to busy highways or factories, are at even greater risk. One 2018 Environmental Protection Agency study found that communities of color are exposed to as much as 1.5 times more airborne pollutants than their white counterparts.
“Our findings highlight the importance of addressing the impact of pollution on disadvantaged communities and point to additional steps all families can take to protect their health,” said Alderete, who hopes her research will influence policymakers to move schools and affordable housing projects away from pollution sources.
The authors caution that more research is needed to determine whether changes in the gut in infancy have lasting impacts, and just what those are. More studies are underway.
Meantime, Alderete advises everyone to take these steps to reduce their exposure to both indoor and outdoor pollutants:
Avoid walking outdoors in high-traffic zones
Consider a low-cost air-filtration system, particularly for rooms children spend a lot of time in
If you are cooking, open the windows
And for new moms, breastfeed for as long as possible
“Breast milk is a fantastic way to develop a healthy microbiome and may help offset some of the adverse effects from environmental exposures,” Alderete said.
VIDEO: IF HUMANS GO TO MARS, WE WON’T BE ABLE TO BRING EVERYTHING WITH US. WE WILL HAVE TO MAKE SOME THINGS THERE. WSU RESEARCHERS USED SIMULATED CRUSHED MARTIAN ROCK AND METAL TO MAKE STRONG, DURABLE PARTS IN A 3D PRINTING PROCESS THAT ONE DAY COULD BE USED ON MARS.view more
CREDIT: WASHINGTON STATE UNIVERSITY
PULLMAN, Wash. – A little Martian dust appears to go a long way. A small amount of simulated crushed Martian rock mixed with a titanium alloy made a stronger, high-performance material in a 3D-printing process that could one day be used on Mars to make tools or rocket parts.
The parts were made by Washington State University researchers with as little as 5% up to 100% Martian regolith, a black powdery substance meant to mimic the rocky, inorganic material found on the surface of the red planet.
While the parts with 5% Martian regolith were strong, the 100% regolith parts proved brittle and cracked easily. Still, even high-Martian content materials would be useful in making coatings to protect equipment from rust or radiation damage, said Amit Bandyopadhyay, corresponding author on the study published in the International Journal of Applied Ceramic Technology.
“In space, 3D printing is something that has to happen if we want to think of a manned mission because we really cannot carry everything from here,” said Bandyopadhyay, a professor in WSU’s School of Mechanical and Materials Engineering. “And if we forgot something, we cannot come back to get it.”
Bringing materials into space can be extremely expensive. For instance, the authors noted it costs about $54,000 for the NASA space shuttle to put just one kilogram of payload (about 2.2 pounds) into Earth orbit. Anything that can be made in space, or on planet, would save weight and money – not to mention if something breaks, astronauts would need a way to repair it on site.
Bandyopadhyay first demonstrated the feasibility of this idea in 2011 when his team used 3D-printing to manufacture parts from lunar regolith, simulated crushed moon rock, for NASA. Since then, space agencies have embraced the technology, and International Space Station has its own 3D-printers to manufacture needed materials on site and for experiments.
For this study, Bandyopadhyay along with graduate students Ali Afrouzian and Kellen Traxel, used a powder-based 3D printer to mix the simulated Martian rock dust with a titanium alloy, a metal often used in space exploration for its strength and heat-resistant properties. As part of the process, a high-powered laser heated the materials to over 2,000 degrees Celsius (3,632 F). Then, the melted mix of Martian regolith-ceramic and metal material flowed onto a moving platform that allowed the researchers to create different sizes and shapes. After the material cooled down, the researchers tested it for strength and durability.
The ceramic material made from 100% Martian rock dust cracked as it cooled, but as Bandyopadhyay pointed out it could still make good coatings for radiation shields as cracks do not matter in that context. But just a little Martian dust, the mixture with 5% regolith, not only did not crack or bubble but also exhibited better properties than the titanium alloy alone, which meant it could be used to make lighter weight pieces that could still bear heavy loads.
“It gives you a better, higher strength and hardness material, so that can perform significantly better in some applications,” he said.
This study is just a start, Bandyopadhyay said, and future research may yield better composites using different metals or 3D-printing techniques.
“This establishes that it is possible, and maybe we should think in this direction because it's not just making plastic parts which are weak but metal-ceramic composite parts which are strong and can be used for any kind of structural parts,” he said.
JOURNAL
International Journal of Applied Ceramic Technology
Martian regolith—Ti6Al4V composites via additive manufacturing
Smoke from the Black Summer wildfires in Australia impacted the climate and high altitude winds of the southern hemisphere for more than a year and a half
Wildfire smoke becomes increasingly important for climate models due to climate change, study
LEIBNIZ INSTITUTE FOR TROPOSPHERIC RESEARCH (TROPOS)
IMAGE: JANUARY 2020: DENSE PLUMES OF SMOKE FROM THE AUSTRALIAN FOREST FIRES DRIFTED THROUGH THE OTHERWISE VERY CLEAN ATMOSPHERE OVER PUNTA ARENAS. SEEN HERE IN THE LIDAR MEASUREMENTS AS A GREEN-YELLOW LAYER AT AN ALTITUDE OF 20 TO 25KM.view more
CREDIT: CRISTOFER JIMENEZ, TROPOS
Leipzig. The 2019/20 wildfires in Australia transported more smoke into the atmosphere than observed ever before anywhere in the world. In the so-called Black Summer, three times as many particles reached high air layers as in the previous record wildfires in Canada during summer 2017. Two analyses led by the Leibniz Institute for Tropospheric Research (TROPOS) now reveal the climate impact of these huge fires: Smoke particles with a total mass of around one million tonnes spread across the southern hemisphere and affected the climate for about one and a half years by warming the upper atmosphere and cooling the lower atmosphere close to Earth’s surface. From the subtropics to Antarctica, sunlight was dimmed even more than during the eruption of the volcano Pinatubo in 1991. The smoke probably also contributed to the record ozone hole over Antarctica in 2020, forming a vortex of 1000 kilometres in diameter that passed over the southern hemisphere for several weeks, which is considered the first evidence that smoke from wildfires can also alter high-altitude winds in the stratosphere. Since such extreme fires are expected to become more frequent due to climate change, it is very important to consider the smoke and its effects on the Earth's energy balance in climate scenarios, the researchers write in the journal Atmospheric Chemistry and Physics (ACP).
Record forest fires in Australia
Between September 2019 and January 2020, almost twice as much area burned as in any other extreme fire in Australia documented to date. The fires peaked between 29 December 2019 and 4 January 2020, which is why they are now referred in scientific literature as the Australian New Year Super Outbreak (ANYSO) and colloquially known as the Black Summer bushfires. Due to the high heat, 38 fire clouds (Pyrocumulonimbus, PyroCb for short) were formed, which transported the smoke to great heights at ten times the speed of an elevator. More than half of these PyroCb clouds transported the smoke particles directly up to a height of 14 to 16 kilometres into the lower stratosphere. As with a volcanic eruption, the same applies to wildfires: the higher the particles reach, the further they spread and the more long-lasting is their effect on the climate. Particles in the lower atmospheric layers are usually washed out quickly by precipitation (within days to a few weeks) and therefore have little effect on the climate.
The wildfires in South-eastern Australia emitted about 1 million tonnes of smoke particles into the atmosphere around the turn of the year 2019/20. This is about four times as much as in previous years' forest fires. The smoke particles dispersed through the mid-latitudes of the southern hemisphere within a few days due to the high-altitude winds and contain, among other things, soot aerosol. These dark particles absorb solar energy and are among the strongest warming short-lived climate forcers. However, smoke from such extreme forest fires has not yet been adequately represented in aerosol climate models. An international research team led by TROPOS has therefore analysed the Black Summer wildfires to better understand the impact of such events on the climate.
CAPTION
The measuring containers of TROPOS with the PollyXT lidar during DACAPO-PESO in Punta Arenas, Chile.
CREDIT
Patric Seifert, TROPOS
Many measurements in the southern hemisphere provide a puzzle picture
For their study, the researchers used satellite data of the optical thickness of aerosol layers (AVHRR of the National Oceanic and Atmospheric Administration (NOAA) and the CALIOP space lidar). They compared the atmospheric opacity with the solar photometer measurements of the international AERONET network, which operates stations in Punta Arenas (Chile), Amsterdam Island (Indian Ocean), Marambio (near the Antarctic Peninsula), Vechernaya Hill (East Antarctica) and at the South Pole, among others. Moreover, the long-term observations carried out with two ground-based Raman lidars in Punta Arenas (Chile) and Río Grande (Argentina) at the southernmost tip of South America were decisive. These measurements can be considered representative of the southern part of the Southern Hemisphere and also allowed comparisons with other extreme wildfires in the Northern Hemisphere. Both measurements originally had different scientific objectives: The lidar observations in Punta Arenas took place as part of the DACAPO-PESO campaign (Dynamics, Aerosol, Cloud And Precipitation Observations in the Pristine Environment of the Southern Ocean) from November 2018 to November 2021. The main objective of this measurement campaign by the University of Magallanes (UMAG), TROPOS and Leipzig University was to study aerosol-cloud interaction processes under the clean conditions of the Southern Hemisphere. The lidar observations in Río Grande were part of the HALO mission SOUTHTRAC-GW (Southern Hemisphere Transport, Dynamics, and Chemistry-Gravity Waves), in which a large international team led by the German Aerospace Center (DLR) investigated atmospheric gravity waves in South America with the HALO research aircraft in September 2019. DLR's Compact Rayleigh Autonomous Lidar (CORAL) was also used, providing important data on the optical properties of the smoke between 15 and 30 kilometres altitude. The large amount of data made it possible to observe a new phenomenon, to compare the wildfires with previous record wildfires in North America and also to establish connections to the ozone hole:
CAPTION
Polarstern during MOSAiC in the Arctic.
CREDIT
Hannes Griesche, TROPOS
A unique smoke vortex
It has long been known that wildfires virtually make their own weather, but a new phenomenon was observed in connection with the Black Summer fires in January-March 2020: A self-sustaining vortex with a diameter of about 1000 km and a vertical extent of about 5 km. This extremely stable vortex persisted in the stratosphere for over 13 weeks, crossed the Pacific eastwards within two weeks and hovered over the tip of South America for more than a week. This was followed by a 10-week journey around the world in a westerly direction that could be tracked for more than 66 000 km by early April 2020. The vortex transported smoke and moisture up to an altitude of 35 km - an altitude not reached by tropospheric aerosols since the eruption of the Pinatubo volcano. This vortex trapped the smoke particles, keeping them from being dispersed and diluted. The absorption of solar radiation by the smoke in the centre led to warming and counter clockwise circulation, like a high-pressure area in the southern hemisphere. "Nothing like this has been observed before. This is the first evidence that smoke also causes changes in winds in the stratosphere and opens up a whole new direction of scientific research. The influence of wildfires on the atmosphere could be much greater than we previously thought," underlines Dr Albert Ansmann from TROPOS.
CAPTION
Interior of the OCEANET container with the green laser of the TROPOS lidar during the MOSAiC expedition in the Arctic 2019/2020.
CREDIT
Martin Radenz, TROPOS
ANYSO as the new "record holder
Lidar measurements by TROPOS from previous years made it possible to compare the wildfires in Australia with two other large fires: The record-breaking wildfires in Canada (Pacific Northwest Event, PNE) in August 2017 had transported only about a third of aerosol mass into the upper stratosphere in comparison. During this event, the smoke from five fire clouds over British Columbia could be observed over Europe until January 2018. Extremely strong fires also occurred in July/August 2019 in Siberia north and northeast of Lake Baikal (SIberian Lake Baikal Event, SILBE), where no fire clouds were observed. The smoke therefore probably rose slowly to high altitudes via solar radiation within a week. Through lidar measurements on the research icebreaker Polarstern, smoke from these fires could be observed in the region around the North Pole during the international MOSAiC expedition between October 2019 and May 2020.
The smoke from the 2017 Canadian wildfires (PNE) comprised about 0.3 million tonnes of material, formed a layer about 1 to 4 kilometres thick, rose to an altitude of 20 kilometres and hovered in the atmosphere for about 8 months. The smoke from the 2019 Siberian wildfires (SILBE) formed a layer about 7 to 10 kilometres thick, rose to an altitude of 18 kilometres and remained suspended in the atmosphere for about 5 months. The smoke from the 2019/20 Australian wildfires (ANYSO) comprised about 1 million tonnes of material, formed a layer about 10 to 14 kilometres thick, rose to an altitude of 24 kilometres and hovered in the atmosphere for about 20 months. "The Australian wildfires of 2019/20 are definitely the wildfires with the largest impact on the atmosphere and global climate to date. The dimensions are comparable to the eruption of Pinatubo in the Philippines in 1991. At that time, the particles reached heights of 25 kilometres and hovered in the atmosphere for about 14 months. Only the size of the particles differs significantly: The ash particles of the volcano, with a diameter of about 1 micrometre, were about twice as large as the smoke particles of the Australian wildfires," reports Albert Ansmann from TROPOS.
CAPTION
Lidar of the OCEANET container during the polar night at MOSAiC.
CREDIT
Ronny Engelmann, TROPOS
Smoke as a catalyst for the ozone hole?
In 2020/21, three events with record-breaking ozone depletion were observed: An extremely strong ozone hole formed over the central Arctic in March/April 2020, and further extreme ones over Antarctica in September to November 2020 and 2021, respectively. During all three events, an unusually large amount of smoke floated in the atmosphere of the polar regions, as shown by the lidar measurements. From the researchers' point of view, this is a clear indication of correlations, as they observed a clear correspondence between the layer with the strongest ozone depletion above the stations of the ozone probes (14-25 km altitude), the layer with an increased particle surface concentration above Punta Arenas (10-24 km altitude) and the altitude range in which the CALIOP satellite data detected polar stratospheric clouds (mainly above Antarctica at 13-26 km altitude). "Polar stratospheric clouds (PSCs) are known to have chemical processes at their surfaces that accelerate ozone depletion. Therefore, we strongly suspect that the smoke has led to these high clouds and that these clouds in turn have led to severe ozone depletion. This would not be good news for the people in and around the polar regions. If, as expected, climate change leads to more frequent and more severe wildfires, the ozone holes would spread over the Arctic and Antarctic, and with them the risk of skin cancer," explains Kevin Ohneiser from TROPOS.
Cooling effect like a large volcanic eruption
The data were also used for a simulation with the modern global aerosol climate model ECHAM6.3-HAM2.3. This model uses an aerosol microphysics model to describe the development of different aerosol types. This allows to estimate their influence on the radiation balance of the atmosphere: The model simulations determined a heating effect in the upper atmosphere (TOA) of +0.5 watts per square metre in the southern hemisphere and +0.25 watts per square metre globally. At the Earth's surface (bottom of the atmosphere, BOA), the solar radiative forcing was estimated to be about -0.75 watts per square metre under clear skies. This corresponds to the cooling effect caused by a large volcanic eruption. "We were surprised at how much the wildfires in southeastern Australia increased the opacity of the upper air layers of the southern hemisphere, hence, changing the radiation balance. These changes influenced the climate in the southern hemisphere for one and a half years. However, they can essentially be attributed to only four days of smoke from pyroconvection," emphasises Dr Bernd Heinold from TROPOS.
Wildfires become more important for climate models
The impact of wildfire aerosol on the energy balance of fires with such high-level fire clouds has probably been underestimated in models so far, as the vertical smoke distribution is crucial for the radiative effect, but there has been little knowledge about this wildfire property. "Such improvements are essential for any estimate of the Earth's energy balance and climate state. Therefore, it is becoming increasingly important to better enable climate models to deal with the impact of wildfires on the atmosphere, as they are expected to increase in frequency and severity worldwide in response to anthropogenic climate warming," explains Prof. Ina Tegen from TROPOS. "The increased risk of severe wildfires is related to extreme drought. More frequent and intense weather extremes also increase the likelihood that these very high reaching fire clouds will form more frequently in the future." Record-breaking fires like the one in Australia in 2019/20 could be repeated in other regions of the world in the years to come and have an increasing impact on the global climate.
High-flying wildfire smoke may threaten ozone layer. Record Arctic ozone loss linked to Siberian wildfires (SCIENCE, 18 Nov 2021): https://doi.org/10.1126/science.acx9681
Project „Dynamics, Aerosol, Cloud and Precipitation Observations in the Pristine Environment of the Southern Ocean (DACAPO-PESO)“: https://dacapo.tropos.de/
Australian wildfire smoke in the stratosphere: the decay phase in 2020/2021 and impact on ozone depletion
COI STATEMENT
At least one of the (co-)authors is a member of the editorial board of Atmospheric Chemistry and Physics. The peer-review process was guided by an independent editor, and the authors also have no other competing interests to declare.
