Microbe dietary preferences influence the effectiveness of carbon sequestration in the deep ocean

The movement of carbon dioxide (CO2) from the surface of the ocean, where it is in active contact with the atmosphere, to the deep ocean, where it can be sequestered away for decades, centuries, or longer, depends on a number of seemingly small processes.

One of these key microscale processes is the dietary preferences of bacteria that feed on organic molecules called lipids, according to a journal article, "Microbial dietary preference and interactions affect the export of lipids to the deep ocean," published in Science.

"In our study, we found incredible variation in what the different microbes preferred to digest. Bacteria seem to have very distinct diet preferences for different lipid molecules. This has real implications for understanding carbon sequestration and the biological carbon pump," said journal article co-author Benjamin Van Mooy, a senior scientist in the Marine Chemistry and Geochemistry Department at the Woods Hole Oceanographic Institution (WHOI). "This study used state-of-the-art methods to link the molecular composition of the sinking biomass with its rates of degradation, which we were able to link to the dietary preferences of bacteria." The biological carbon pump is a process where biomass sinks from the ocean surface to the deep ocean.

About 5 to 30% of surface ocean particulate organic matter is composed of lipids, which are carbon-rich fatty acid biomolecules that microbes use for energy storage and cellular functions. As the organic matter sinks to the deep sea, diverse communities of resident microbes degrade and make use of the lipids, exerting an important control on global CO2 concentrations. Understanding this process is vital to improve our ability to forecast global carbon fluxes in changing ocean regimes. Geographic areas where more lipids reach the deep ocean undegraded could be hotspots for natural carbon sequestration.

"Bacteria isolated from marine particles exhibited distinct dietary preferences, ranging from selective to promiscuous degraders," the article states. "Using synthetic communities composed of isolates with distinct dietary preferences, we showed that lipid degradation is modulated by microbial interactions. A particle export model incorporating these dynamics indicates that metabolic specialization and community dynamics may influence lipid transport efficiency in the ocean's mesopelagic zone." The mesopelagic zone extends about 200-1000 meters below the ocean surface.

"I was thrilled to see how much there is to learn about the functioning of the ocean by combining two technologies- high-end chemical analysis and microscale imaging-that have historically never been used together," said co-author Roman Stocker, professor at the Institute of Environment Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Switzerland, "I believe that work at the interface between the exciting technologies we now have available in microbial oceanography will continue to yield important insights into how microbes shape our oceans, now and into the future."

"Scientists are starting to understand that lipids in the ocean can vary significantly depending on different environments, such as the coast versus the open ocean, and the season," said Van Mooy. "With this information, researchers can start to consider whether there are places in the ocean where lipids sink and are sequestered very efficiently, while there may be other locations where lipids are barely sequestered at all or are very inefficiently sequestered."

"What excites me about this paper is that it shows bacteria are not just eating any type of lipid, but are very specialized and, like us, have specific food preferences," said article co-author Lars Behrendt, associate professor and SciLifeLab fellow at the Science for Life Laboratory, Department of Organismal Biology, Uppsala University, Sweden. "This changes how we think about how microorganisms consume food in their natural environment and how they might help each other or compete for the same resource. It also supports the idea that combinations of bacteria better break down specific compounds, including lipids, or to achieve other desired functions."

In addition to studying specific bacteria species in isolation, the researchers also looked at how dietary preference affects degradation rates by multispecies communities of bacteria, which they stated is ecologically more relevant than species in isolation. The researchers found that simple synthetic co-cultures exhibited different degradation rates and delay times when compared to monocultures. The researchers also noted that the degradation of particulate organic matter in the natural environment is even more complex than what is described in the study.

"Phytoplankton are the main reason the ocean is one of the biggest carbon sinks. These microscopic organisms play a huge role in the world's carbon cycle -- absorbing about as much carbon as all the plants on land combined," said co-author Uria Alcolombri, senior lecturer, Alexander Silberman Institute of Life Sciences, Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Israel. "It's fascinating that we can study tiny microbial processes under the microscope while uncovering the biological factors that regulate this massive 'digestive system' of the ocean."

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New study unveils 16,000 years of climate history in the tropical Andes

A new study that explores ancient temperatures and rainfall patterns in the tropical Andes of South America has revealed how 16,000 years of climate history in this part of the world was driven by carbon dioxide levels and ocean currents from global climate events.

Led by Brown University researchers, the study marks the first high-resolution temperature record covering the past 16,000 years in the tropical Andes and could help scientists predict and mitigate future climate impacts in tropical regions of the planet. The work is described in the Proceedings of the National Academy of Science.

"Usually when we study climate change in the past, we emphasize the Northern Hemisphere or Southern Hemisphere because of the outsized role they play in affecting climates all over the globe," said Boyang Zhao, a scientist in Brown's Department of Earth, Environmental and Planetary Sciences and the study's first author. "One of the biggest questions we are getting at is what are the driving factors behind temperature history in this part of the tropics, so that we can begin to potentially apply that data and knowledge to other tropical regions."

Along with future implications, the new study provides a unique look at the way distinct and distant parts of the world influence temperature and weather elsewhere, emphasizing how regional climates are connected to global climate changes.

"Our evidence here suggests that temperatures in this region of the world are more influenced by the Southern Hemisphere -- so places like Antarctica," Zhao said.

The study focused on an analysis of sediment samples from Laguna Llaviucu, a lake located in Ecuador's Cajas National Park. The measurements from the sediment samples showed that temperature variations in the tropical Andes closely aligned with climate events that saw the planet's temperatures rise and fall during the past 16,000 years.

Overall, the evidence showed that the main driver in these temperature fluctuations was the concentration of CO2. Researchers saw evidence that the tropical Andean temperatures track with Antarctic temperatures, which are mainly controlled by carbon dioxide concentrations. The findings showed that about 17,000 to 14,000 years ago, tropical Andean temperatures rose when carbon dioxide increased and that the temperatures remained relatively stable about 12,000 years ago when carbon dioxide levels remained relatively stable.

Zhao said that the findings support previous research identifying carbon dioxide as a key driver of global temperature changes since the last Ice Age.

The study also highlighted the role of ocean currents that move warm water from the tropics to the North Atlantic. During a cooling period known as the Antarctic Cold Reversal 14,500 years ago, the northward current was strengthened, causing it to transport more heat northward and cool sea surface temperatures in the south. The researchers found that this cooling effect extended to the tropical Andes.

To reconstruct past climate conditions, the researchers analyzed lipid biomarkers and hydrogen isotopes collected in 2009 from Laguna Llaviucu by scientist Mark Bush from the Florida Institute of Technology. Lipid biomarkers are chemical compounds that provide clues about past temperatures and rainfall patterns. The high-resolution data, combined with accurate dating techniques, allowed the team to create a detailed timeline of climate changes over the past 16,000 years.

According to the researchers, this is the first time organic biomarkers have been used to put together a quantitative climate history for tropical South America. It is traditionally difficult to reconstruct temperatures from the tropics.

The study also points out a number of regional differences in temperature patterns, like how the tropical Andes and Southeast Asia cooled during certain historical periods while other regions like Africa did not.The research also shows how local factors may help to counteract the global effects of rising CO2 levels by looking at differences between past temperature models and what the sediment data show.

The researchers from Brown plan to continue to explore past temperature patterns in this part of the world that historically lacks complete climate records.

"Mountain environments are some of the most sensitive regions on Earth to climate change," said James Russell, a professor of Earth, environmental, and planetary sciences at Brown who oversaw the new research. "In fact, in the near future, high tropical mountains, such as the Andes, are predicted to experience a rate of warming second only to the Arctic, which is the fastest warming part of the planet."

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Great Salt Lake a significant source of greenhouse gas emissions

Newly announced research by Royal Ontario Museum (ROM) examining greenhouse gas emissions from the drying lake bed of Great Salt Lake, Utah, calculates that 4.1 million tons of carbon dioxide and other greenhouse gases were released in 2020. This research suggests that drying lake beds are an overlooked but potentially significant source of greenhouse gases, which may further increase due to climate change. These results were announced in the paper, "A desiccating saline lake bed is a significant source of anthropogenic greenhouse gas emissions," published in the journal One Earth.

"Human-caused desiccation of Great Salt Lake is exposing huge areas of lake bed and releasing massive quantities of greenhouse gases into the atmosphere," said Soren Brothers, who led this research and is ROM's Allan and Helaine Shiff Curator of Climate Change. "The significance of lake desiccation as a driver of climate change needs to be addressed in greater detail and considered in climate change mitigation and watershed planning."

From year to year, Great Salt Lake's water level varies, largely depending on the volume of meltwater that flows into the lake from the surrounding mountains -- from record highs in the 1980s to a record low in 2022. However, it is human-related consumption by agriculture, industry, and municipal uses, that consume ever-increasing amounts of freshwater that, over the years, has depleted the lake. Elsewhere around the world, these same competing uses for water are having a significant impact on lake levels. As iconic saline lakes such as the Aral Sea, Lake Urmia, the Caspian Sea, and Great Salt Lake dry up, they not only destroy critical habitat for biodiversity and create air quality conditions that deteriorate human health, but they also accelerate climate change as newly exposed sediments emit carbon dioxide and methane.

The research team measured carbon dioxide and methane emissions from the exposed sediments of Great Salt Lake, Utah, from April to November 2020, and compared them with aquatic emissions estimates to determine the anthropogenic greenhouse gas emissions associated with desiccation. Calculations based on this sampling indicate the lake bed emitted 4.1 million tons of greenhouse gases to the atmosphere, primarily (94%) as carbon dioxide, constituting an approximately 7% increase to Utah's human-caused greenhouse gas emissions.

Fieldwork was conducted while Soren Brothers was Assistant Professor of Limnology at Utah State University, and lead author, Melissa Cobo, was a master's student at USU. Co-author Tobias Goldhammer is a collaborating researcher at the Leibniz Institute for Freshwater Research (IGB Institute) in Berlin, Germany. Measurements of carbon dioxide and methane gases were made every two weeks from the dried-up lake bed using a portable greenhouse gas analyzer attached to a closed chamber. Seven sites at one location at the south end of the lake were visited repeatedly over the course of the year, and another three locations were sampled during an intensive three-day campaign to determine spatial variability across the lake, which at 1,700 square miles (4,400 square kilometres) is the largest saline lake in the western hemisphere.

As methane is 28 times more powerful a greenhouse gas than carbon dioxide, the global warming impact of these emissions was calculated as "carbon dioxide equivalents" to account for the greater impact of methane. Ultimately, these data indicated that greenhouse gas emissions from the dried lake bed were strongly and positively related to warm temperatures, even at sites that have been exposed for over two decades. To determine whether the lake historically would have been a significant source of greenhouse gases, the team carried out measurements of near-shore greenhouse gas emissions from the lake, as well as analyzing water chemistry collected by the team and government data sets. Together, these analyses showed that the original lake was not likely a significant source of greenhouse gases to the atmosphere, making the dried-up lake bed a novel driver of atmospheric warming.

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How well does tree planting work in climate change fight? It depends

Using trees as a cost-effective tool against climate change is more complicated than simply planting large numbers of them, an international collaboration that includes an Oregon State University scientist has shown.

Jacob Bukoski of the OSU College of Forestry and seven other researchers synthesized data from thousands of reforestation sites in 130 countries and found that roughly half the time it's better just to let nature take its course.

Findings of the study led by Conservation International were published today in Nature Climate Change.

"Trees can play a role in climate change mitigation, for multiple reasons," Bukoski said. "It's pretty easy to understand that forests pull carbon dioxide from the atmosphere and store it, and trees are something pretty much everyone can get behind -- we have seen multiple bipartisan acts for tree planting introduced in Congress. This study brings a nuanced perspective to the whole 'should we plant trees to solve climate change' debate."

Bukoski notes that expanding forests globally has been widely proposed as a key tactic against climate change since forests sequester atmospheric carbon dioxide in their biomass and soils. Harvested timber also stores carbon in the form of wood products.

There are two basic approaches to forest expansion, Bukoski said.

"Generally speaking, we can let forests regenerate on their own, which is slow but cheap, or take a more active approach and plant them, which speeds up growth but is more expensive," he said. "Our study compares these two approaches across reforestable landscapes in low- and middle-income countries, identifying where naturally regenerating or planting forests is likely to make more sense."

Using machine learning and regression models, the scientists found that natural regeneration would be most cost effective over a 30-year period for 46% of the areas studied, and planting would be most cost effective for 54%.

They also determined that using a combination of the two approaches across all areas would be 44% better than natural regeneration alone and 39% better than planting by itself.

"If your objective is to sequester carbon as quickly and as cheaply as possible, the best option is a mix of both naturally regenerating forests and planting forests." Bukoski said.

The study suggests that natural regeneration is especially cost effective relative to plantation forestry in much of western Mexico, the Andean region, the Southern Cone of South America, West and Central Africa, India, Southern China, Malaysia and Indonesia.

Conversely, plantations are preferable to natural regeneration in much of the Caribbean, Central America, Brazil, northern China, mainland Southeast Asia, the Philippines and North, East and Southern Africa.

"Which method is more cost effective in a given location is a function of multiple factors, including opportunity cost, relative carbon accumulation and harvest rates, and relative implementation costs," Bukoski said.

Other scientists in the collaboration were Jonah Busch and Bronson Griscom of Conservation International, Susan Cook-Patton of The Nature Conservancy, David Kaczan of the World Bank, Yuanyuan Yi of Peking University, Jeff Vincent of Duke University and Matthew Potts of the University of California, Berkeley.

The authors stress that reforestation is a complement to, not a replacement for, reducing emissions from fossil fuels. Achieving the entire mitigation potential of reforestation over 30 years would amount to less than eight months of global greenhouse gas emissions, they note.

The authors add that carbon is just one consideration when growing trees. Biodiversity, demand for wood products, support of local livelihoods, and non-carbon biophysical effects must also be considered when deciding where and how to reforest landscapes.

Read more at Science Daily

New humidity-driven membrane to remove carbon dioxide from the air

A new ambient-energy-driven membrane that pumps carbon dioxide out of the air has been developed by Newcastle University researchers.

Direct air capture was identified as one of the 'Seven chemical separations to change the world'. This is because although carbon dioxide is the main contributor to climate change (we release ~40 billion tons into the atmosphere every year), separating carbon dioxide from air is very challenging due to its dilute concentration (~0.04%).

Prof Ian Metcalfe, Royal Academy of Engineering Chair in Emerging Technologies in the School of Engineering, Newcastle University, UK, and lead investigator states, "Dilute separation processes are the most challenging separations to perform for two key reasons. First, due to the low concentration, the kinetics (speed) of chemical reactions targeting the removal of the dilute component are very slow. Second, concentrating the dilute component requires a lot of energy."

These are the two challenges that the Newcastle researchers (with colleagues at the Victoria University of Wellington, New Zealand, Imperial College London, UK, Oxford University, UK, Strathclyde University, UK and UCL, UK) set out to address with their new membrane process. By using naturally occurring humidity differences as a driving force for pumping carbon dioxide out of air, the team overcame the energy challenge. The presence of water also accelerated the transport of carbon dioxide through the membrane, tackling the kinetic challenge.

The work is published in Nature Energy and Dr Greg A. Mutch, Royal Academy of Engineering Fellow in the School of Engineering, Newcastle University, UK explains, "Direct air capture will be a key component of the energy system of the future. It will be needed to capture the emissions from mobile, distributed sources of carbon dioxide that cannot easily be decarbonised in other ways."

"In our work, we demonstrate the first synthetic membrane capable of capturing carbon dioxide from air and increasing its concentration without a traditional energy input like heat or pressure. I think a helpful analogy might be a water wheel on a flour mill. Whereas a mill uses the downhill transport of water to drive milling, we use it to pump carbon dioxide out of the air."

Separation processes

Separation processes underpin most aspects of modern life. From the food we eat, to the medicines we take, and the fuels or batteries in our car, most products we use have been through several separation processes. Moreover, separation processes are important for minimising waste and the need for environmental remediation, such as direct air capture of carbon dioxide.

However, in a world moving towards a circular economy, separation processes will become even more critical. Here, direct air capture might be used to provide carbon dioxide as a feedstock for making many of the hydrocarbon products we use today, but in a carbon-neutral, or even carbon-negative, cycle.

Most importantly, alongside transitioning to renewable energy and traditional carbon capture from point sources like power plants, direct air capture is necessary for realising climate targets, such as the 1.5 °C goal set by the Paris Agreement.

The humidity-driven membrane

Dr Evangelos Papaioannou, Senior Lecturer in the School of Engineering, Newcastle University, UK explains, "In a departure from typical membrane operation, and as described in the research paper, the team tested a new carbon dioxide-permeable membrane with a variety of humidity differences applied across it. When the humidity was higher on the output side of the membrane, the membrane spontaneously pumped carbon dioxide into that output stream."

Using X-ray micro-computed tomography with collaborators at UCL and the University of Oxford, the team were able to precisely characterise the structure of the membrane. This enabled them to provide robust performance comparisons with other state-of-the-art membranes.

A key aspect of the work was modelling the processes occurring in the membrane at the molecular scale. Using density-functional-theory calculations with a collaborator affiliated to both Victoria University of Wellington and Imperial College London, the team identified 'carriers' within the membrane. The carrier uniquely transports both carbon dioxide and water but nothing else. Water is required to release carbon dioxide from the membrane, and carbon dioxide is required to release water. Because of this, the energy from a humidity difference can be used to drive carbon dioxide through the membrane from a low concentration to a higher concentration.

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Climate change and mercury pollution stressed plants for millions of years

The link between massive flood basalt volcanism and the end-Triassic (201 million years ago) mass-extinction is commonly accepted. However, exactly how volcanism led to the collapse of ecosystems and the extinction of entire families of organisms is difficult to establish. Extreme climate change from the release of carbon dioxide, degradation of the ozone layer due to the injection of damaging chemicals, and the emissions of toxic pollutants, are all seen as contributing factors. One toxic element stands out: mercury. As one of the most toxic elements on Earth, Hg is a metal that is emitted from volcanoes in gaseous form, and thus has the capacity to spread worldwide. A new study in Nature Communications adds new compelling evidence for the combined effects of global warming and widespread mercury pollution that continued to stress plants long after volcanic activity had ceased.

An international team of Dutch, Chinese, Danish, British, and Czech scientists studied sediments from Northern-Germany in a drill-core (Schandelah-1) that spans the uppermost Triassic to lower Jurassic for microfossils and geochemical signals. A study of pollen and spore abundances revealed a profusion of fern spores showing a range of malformations, from abnormalities in wall structure to evidence for botched meiotic divisions, leading to unseparated, dwarfed, and fused fern spores. "Seeing the sheer amount and different types of malformed fern spores in sediment samples from a coastal lagoon, dating back 201 million years ago is truly astonishing. It means there must have been very many ferns being stressed," explains Remco Bos, a PhD candidate at Utrecht University and lead author of the study. "It is also not something we see regularly during other periods that also contain many fern fossils, making it a true signal connected to the end-Triassic mass-extinction event."

Deforestation and ferns

The results from Bos and co-authors confirm earlier work by co-authors Sofie Lindström (University of Copenhagen), Hamed Sanei (Aarhus University), and Bas van de Schootbrugge (Utrecht University), who previously produced similar data obtained from cores from Denmark and from nearby outcrops in Sweden. According to Sofie Lindström: "Ferns replaced trees across the extinction interval in response to dramatic environmental changes likely driven by heat stress, strongly increased monsoonal rainfall, and increased forest fire activity. Palynological results show that a pioneering fern vegetation spread across vast swaths of coastal lowlands in Northwestern Europe from Sweden and Denmark to Germany, France, Luxemburg, and Austria in response to widespread deforestation." Ferns are hardy plants, often colonizing disturbed environments, including newly formed volcanic islands or landscapes devastated by volcanism or wildfires. "What is extraordinary here is that the ferns that produced all these malformed spores in all these different sites, did not go extinct. While other plants went extinct, ferns were apparently robust enough to continue, which could also be related to their different mercury tolerance."

Climate variability

In this new study, Bos and co-authors show that the ferns, which took advantage of the dieback of forests, themselves were subjected to stress from Hg-pollution well beyond the immediate extinction interval. "We found four more intervals with high levels of Hg concentrations and high numbers of malformed spores in the 1.3 to 2 million years following the extinction interval," explains Remco Bos. This interval, known as the Hettangian, was a time of continuing adverse conditions in the oceans, with generally low diversities among marine invertebrates, such as ammonites and bivalves. On land, however, vegetation appeared to have recovered quicker. "We now show that this forest ecosystem continued to be perturbed repeatedly for at least 1.3 million years, but perhaps as long as 2 million years," Bos explains.

The four additional episodes of high Hg concentrations and high fern spore malformations were unlikely connected to later phases of Central Atlantic Magmatic Province volcanism. Instead, Bos and co-authors show that these periods correspond closely to the long eccentricity cycle, the major variation in the shape of Earth's orbit that moves Earth closer or further away from the Sun every 405 thousand years. During eccentricity maxima Earth moves closer to the Sun allowing for more sunlight to reach the Earth surface. As the Earth's atmosphere was already supercharged with carbon dioxide from the large-scale volcanism, this cyclic modulation of the climate system repeatedly triggered forest dieback, allowing for the renewed spread of pioneer ferns. As is shown by the correlation with high Hg contents, malformations in fern spores during these episodes were also the result of mercury poisoning. But where did this Hg come from?

Hg-isotopes

A crucial data set was generated at Tianjin University (China) by Wang Zheng, a co-corresponding author and geochemist specialized in metal isotope studies, especially Hg-isotopes. Mercury has different stable isotopes that behave differently in the environment. During reactions in nature, for example the expulsion from volcanism, deposition from the atmosphere, and the uptake by organisms, Hg-isotopes can become fractionated, enriching one pool in heavier isotopes, and others in lighter isotopes. Sediments with elevated levels of Hg and malformed spores also show clear variations in Hg-isotopes. "Based on the Hg-isotope variations we were able to link an initial pulse in Hg enrichment at the Triassic-Jurassic boundary to the emission of mercury from flood basalt volcanism," Wang Zheng explains. "However, the four other pulses in mercury had a different isotopic composition, indicating they were mainly driven by Hg input from soil erosion and photochemical reduction."

Climate change and toxic pollution

The combined geochemical and microfossil data thus paint a picture of a much more complex and drawn-out sequence of events, starting with massive volcanism driving climate change and releasing toxic pollutants, followed by episodic pulses of disturbance in the aftermath of the extinction event lasting for at least 1.3 million years. Dr. Tomas Navratil from the Czech Academy of Sciences, a co-author on the paper and a specialist for modern-day mercury pollution, agrees with this scenario. "Our work on polluted sites in the Czech Republic does show evidence for episodic remobilization from forest soils, especially during hot summers, and in places that are more exposed to sunlight causing the photochemical reduction of mercury and re-release to the atmosphere of previously stored mercury."

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CO2 worsens wildfires by helping plants grow

By fueling the growth of plants that become kindling, carbon dioxide is driving an increase in the severity and frequency of wildfires, according to a UC Riverside study.

The worldwide surge in wildfires over the past decade is often attributed to the hotter, drier conditions of climate change. However, the study found that the effect of increasing levels of carbon dioxide (CO2) on plants may be a bigger factor.

"It's not because it's hotter that things are burning, it's because there's more fuel, in the form of plants," said UCR doctoral student in Earth and planetary sciences and study author James Gomez.

This conclusion, and a description of the eight model experiments that produced it, have been published in Communications Earth & Environment.

To convert light into food in a process called photosynthesis, plants require CO2. Burning fossil fuels for heat, electricity, and transportation is adding increasing levels of CO2 into the atmosphere. Plants use the extra CO2 to make carbohydrates that help them grow, leading to an increase in biomass that burns.

Certainly, heat waves and drought occur more frequently in today's climate than they did 50 years ago. These are conditions that cause plants to wither and die. As they dry out and die, they burn more easily. The models accounted for these effects on plants, as well as for different types of plants, and for the increase in atmospheric CO2.

"Warming and drying are still important fire factors. These are the conditions that make the extra plant mass more flammable," said UCR professor of Earth sciences Robert Allen.

The models analyzed by the research team all assumed an idealized 1% per year increase in atmospheric CO2 concentrations since 1850. The idealized increase is meant to isolate the effects of the greenhouse gas on wildfire activity.

"These experiments are mainly looking at the contribution of CO2 to changes in wildfire activity," Gomez said. "That's the only thing that's changing in these models. Other drivers of climate change and wildfire activity do not change through time," Gomez said. "This includes, for example, changes in other greenhouse gases like methane, as well as changes in land use."

Seasons are still important factors in promoting wildfires, and fires still occur more often during "fire seasons." Dry, windy conditions help spread the flames faster, increasing the size of the burned area. "However, our study shows the increase in fires during hotter seasons is driven by fuel load rather than an increase in the number of what some consider 'fire weather' days," Gomez said.

This means megafires can often happen outside of what is considered fire season. As an example, the biggest wildfire on record in Texas, with more than a million acres burned, occurred this past February.

The researchers hope that their results inspire others to conduct additional studies of the factors driving the increase in wildfires. In addition, they hope that policymakers recognize the urgent need to decrease the amount of CO2 that people release into the atmosphere.

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Study shedding new light on Earth's global carbon cycle could help assess liveability of other planets

Research has uncovered important new insights into the evolution of oxygen, carbon, and other vital elements over the entire history of Earth – and it could help assess which other planets can develop life, ranging from plants to animals and humans.

The study, published today in Nature Geoscience and led by a researcher at the University of Bristol, reveals for the first time how the build up of carbon-rich rocks has accelerated oxygen production and its release into the atmosphere.

Until now the exact nature of how the atmosphere became oxygen-rich has long eluded scientists and generated conflicting explanations.

As carbon dioxide is steadily emitted by volcanoes, it ends up entering the ocean and forming rocks like limestone.

As global stocks of these rocks build up they can then release their carbon during tectonic processes, including mountain building and metamorphism.

Using this knowledge, the scientists built a unique sophisticated computer model to more accurately chart key changes in the carbon, nutrient and oxygen cycles deep into Earth’s history, over 4 billion years of the planet’s lifetime.

Lead author and biogeochemist Dr Lewis Alcott, Lecturer in Earth Sciences at the University of Bristol, said: “This breakthrough is important and exciting because it may help us understand how planets, other than Earth, have the potential to support intelligent, oxygen-breathing life.

“Previously we didn’t have a clear idea of why oxygen rose from very low concentrations to present-day concentrations, as computer models haven’t previously been able to accurately simulate all the possible feedbacks together. This has puzzled scientists for decades and created different theories.”

The discovery indicates that older planets, originating billions of years ago like Earth, may have better prospects to accumulate enough carbon-rich deposits in their crust, which could facilitate rapid recycling of carbon and nutrients for life.

The findings showed this gradual carbon enrichment of the crust results in ever-increasing recycling rates of carbon and various minerals, including the nutrients needed for photosynthesis, the process green plants use sunlight to absorb nutrients from carbon dioxide and water.

This cycle therefore steadily speeds up oxygen production over the passage of Earth’s history.

The research, which started whilst Dr Alcott was a Hutchinson Postdoctoral Fellow at Yale University in the United States, paves the way for future work to further unravel the complex interrelationships between planetary temperature, oxygen, and nutrients.

Read more at Science Daily

Climate change will see Australia's soil emit CO2 and add to global warming

New Curtin University research has shown the warming climate will turn Australia's soil into a net emitter of carbon dioxide (CO2), unless action is taken.

Soil helps to keep the planet cool by absorbing carbon, however as the climate gets warmer its ability to retain carbon decreases -- and in some instances can start to release some carbon back into the air.

A global research team -- led by Professor Raphael Viscarra Rossel from Curtin's School of Molecular and Life Sciences -- predicted the changes in the amount of carbon in Australia's soil between now and the year 2100.

To do so, the team ran simulations using three different paths for society: an eco-focused 'sustainable' scenario, a 'middle-of-the-road' scenario and another which predicted a continued reliance on 'fossil-fuelled development'.

It found Australian soil will be a net emitter and could account for 8.3 per cent of Australia's total current emissions under the 'sustainable' scenario and more than 14 per cent by 2045 under the 'middle-of-the-road' and 'fossil-fuelled' scenarios.

By 2100, soil emissions under both scenarios are predicted to account for an even higher proportion of total emissions, but the predictions are more uncertain.

While some areas with arable farmland could continue to store carbon, the study found it would not be enough to offset the amounts of carbon lost from the soil in areas which are more sensitive to warmer weather, such as coastal regions and Australia's vast rangelands.

Australian soil holds an estimated 28 gigatons of carbon, 70 per cent of which is stored in these rangelands.

"Unless farming methods are further improved so farmland soils can continue to store carbon, any gains and benefit will likely decrease by 2045 and worsen in time, if the Earth continues to warm at its current rate," Professor Viscarra Rossel said.

"This means Australia's soil could release even more carbon into the air instead of storing it, which will in turn make climate change worse.

"If emissions continue at the current rate, the Earth's temperature is expected to reach 2 degrees above pre-industrial temperatures sometime this century, which is predicted to have dire consequences and

potentially catastrophic impacts for the planet."

Professor Viscarra Rossel said more sustainable pathways and improved management and conservation of soils were essential for Australia to meet its emissions reduction goals.

"Ensuring Australia's rangeland soils can maintain their carbon stocks is imperative: capturing and storing additional carbon will require interdisciplinary science, innovation, cultural awareness and effective policies" Professor Viscarra Rossel said.

"It will be challenging, given the rangelands' drier and more variable climate, its relatively sparse vegetation and other factors such as bushfires -- however, only a slight change over such large areas will make a positive difference.

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Scientists propose new method for tracking elusive origins of CO2 emissions from streams

A team of researchers from the University of Massachusetts Amherst that specializes in accounting for the carbon dioxide release by streams, rivers and lakes recently demonstrated that the chemical process known as "carbonate buffering" can account for the majority of emissions in highly alkaline waters. Furthermore, carbonate buffering distorts the most commonly used method of tracking the origins of CO2 in streams. The research, published in Global Biogeochemical Cycles, proposes a better method for tracking the origin of riverine CO2 emissions.

Inland waters, including streams, rivers and lakes, account for roughly 5.5 gigatons of CO2 emissions annually -- about 15% of what humans emit.

But current climate models have trouble accounting for this carbon, in part because, says Matthew Winnick, assistant professor of Earth, Geographic and Climate Sciences at UMass Amherst and the paper's lead author, much of this carbon seems to be produced cryptically, through carbonate buffering.

"The process is a little weird," says Winnick. "It acts as a kind of hidden reserve pool of CO2, replenishing carbon that is lost to the atmosphere, and ultimately increasing the amount of CO2 available for off-gassing."

To show how this hidden pool operates, Winnick and his co-author, then-UMass graduate student Brian Saccardi, looked to studies that focused on the carbon content of the oceans.

"Carbonate buffering is a really well-known phenomenon in the ocean," says Winnick, "and even though oceans work differently from inland waters, we were able to borrow the geochemical equations to build a series of models that could account for a wide range of river and stream conditions."

So what is carbonate buffering? It begins with CO2 -- which is everywhere: in the air, in the soil and in water.

When CO2 dissolves in water, it can react to form carbonic acid, which, through further reactions, can then become bicarbonate and carbonate.

This reaction can also run in reverse, which means that high levels of bicarbonate and carbonate can act as reserve pools of CO2, driving emissions.

This entire balance of CO2, water and carbonate is called "carbonate buffering," and the carbonate reserves can be emitted as a greenhouse gas from stream systems.

Indeed, Winnick and Saccardi found that this hidden pool can account for more than 60% of CO2 emissions under alkaline conditions.

There's yet another trick that carbonate buffering has up its sleeve.

In the era of global warming, it is critically important to know both how much carbon is being emitted overall and where this carbon is coming from.

"While we don't think stream emissions contribute to global warming, there is a big question about whether these emissions will change as climate warms, which could amplify warming in the future. To predict changes, we need to know where the CO2 is coming from," says Winnick.

But figuring out which molecule of CO2 came from which source is not a simple task.

To track carbon, especially carbon emitted by bodies of water, scientists often use carbon isotopes, or versions of carbon with different masses, which act as a sort of forensic signature that can indicate the carbon's origin.

However, Winnick and Saccardi discovered that isotope signals in streams are highly sensitive to carbonate buffering reactions.

"The primary way we use isotopes to track sources is through their relationship with CO2 concentrations, but carbonate buffering causes these relationships to break down," says Winnick.

This breakdown can point to the wrong carbon culprit if not properly accounted for.

Read more at Science Daily

Viruses that can help 'dial up' carbon capture in the sea

Armed with a catalog of hundreds of thousands of DNA and RNA virus species in the world's oceans, scientists are now zeroing in on the viruses most likely to combat climate change by helping trap carbon dioxide in seawater or, using similar techniques, different viruses that may prevent methane's escape from thawing Arctic soil.

By combining genomic sequencing data with artificial intelligence analysis, researchers have identified ocean-based viruses and assessed their genomes to find that they "steal" genes from other microbes or cells that process carbon in the sea. Mapping microbial metabolism genes, including those for underwater carbon metabolism, revealed 340 known metabolic pathways throughout the global oceans. Of these, 128 were also found in the genomes of ocean viruses.

"I was shocked that the number was that high," said Matthew Sullivan, professor of microbiology and director of the Center of Microbiome Science at The Ohio State University.

Having mined this massive trove of data via advances in computation, the team has now revealed which viruses have a role in carbon metabolism and are using this information in newly developed community metabolic models to help predict how using viruses to engineer the ocean microbiome toward better carbon capture would look.

"The modeling is about how viruses may dial up or dial down microbial activity in the system," Sullivan said. "Community metabolic modeling is telling me the dream data point: which viruses are targeting the most important metabolic pathways, and that matters because it means they're good levers to pull on."

Sullivan presented the research today (Feb. 17, 2024) at the annual meeting of the American Association for the Advancement of Science in Denver.

Sullivan was the virus coordinator for the Tara Oceans Consortium, a three-year global study of the impact of climate change on the world's oceans and the source of 35,000 water samples containing the microbial bounty. His lab focuses on phages, viruses that infect bacteria, and their potential to be scaled up in an engineering framework to manipulate marine microbes into converting carbon into the heaviest organic form that will sink to the ocean floor.

"Oceans soak up carbon, and that buffers us against climate change. CO2 is absorbed as a gas, and its conversion into organic carbon is dictated by microbes," Sullivan said. "What we're seeing now is that viruses target the most important reactions in these microbial community metabolisms. This means we can start investigating which viruses could be used to convert carbon toward the kind we want.

"In other words, can we strengthen this massive ocean buffer to be a carbon sink to buy time against climate change, as opposed to that carbon being released back into the atmosphere to accelerate it?"

In 2016, the Tara team determined that carbon sinking in the ocean was related to the presence of viruses. It is thought that viruses help sink carbon when virus-infected carbon-processing cells cluster into larger, sticky aggregates that drop to the ocean floor. The researchers developed AI-based analytics to identify from thousands of viruses which few are "VIP" viruses to culture in the lab and work with as model systems for ocean geoengineering.

This new community metabolic modeling, developed by collaborator Professor Damien Eveillard of the Tara Oceans Consortium, helps them understand what unintended consequences might be of such an approach. Sullivan's lab is taking these oceanic lessons learned and applying them to using viruses to engineer microbiomes in human settings to aid recovery from spinal cord injury, improve outcomes for infants born to mothers with HIV, combat infection in burn wounds, and more.

"The conversation we're having is, 'How much of this is transferable?'" said Sullivan, also a professor of civil, environmental and geodetic engineering. "The overall goal is engineering microbiomes toward what we think is something useful."

He also reported on early efforts to use phages as geoengineering tools in an entirely different ecosystem: the permafrost in northern Sweden, where microbes both change the climate and respond to climate change as the frozen soil thaws. Virginia Rich, associate professor of microbiology at Ohio State, is co-director of the National Science Foundation-funded EMERGE Biology Integration Institute based at Ohio State that organizes the microbiome science at the Sweden field site. Rich also co-led previous research that identified a lineage of single-cell organisms in the thawing permafrost soil as a significant producer of methane, a potent greenhouse gas.

Rich co-organized the AAAS session with Ruth Varner of the University of New Hampshire, who co-directs the EMERGE Institute, which is focusing on better understanding how microbiomes respond to permafrost thaw and the resulting climate interactions.

Sullivan's talk was titled "From ecosystems biology to managing microbiomes with viruses," and was presented at the session titled "Microbiome-Targeted Ecosystem Management: Small Players, Big Roles."

Read more at Science Daily

Greenhouse gas repurposed

Cutting-edge University of Auckland research converted waste carbon dioxide into a potential precursor for chemicals and carbon-free fuel.

Dr Ziyun Wang's researchers in the School of Chemical Sciences, in collaboration with researchers at Chinese institutions, have demonstrated a method for turning CO2 into formic acid, reported in the journal Nature.

In benchtop experiments, a catalyst made from waste lead-acid batteries enabled a transformation which hadn't been possible using previous catalysts.

Formic acid -- the same substance produced by ants (formica is the Latin word for ant) -- is a colourless and pungent liquid with potential as a transportation fuel, for storing electrical energy and for enabling the petrochemical industry to cut CO2 emissions.

As emissions of carbon dioxide, the primary greenhouse gas, rise each year, scientists are looking into options for the capture and storage of CO2, for repurposing CO2, and for pursuing a carbon-free economy.

Wang's group is one of the world leaders in research into CO2 electrochemical reduction (CO2RR) using acidic rather than alkaline conditions.

"This innovation opens up exciting possibilities for carbon-neutral technologies," he says.

"In the future, cars and gas stations could be using repurposed carbon dioxide."

In tests, the new method efficiently converted CO2. for more than 5,000 hours, and the researchers' calculations suggest it can be cost-effectively scaled up for industry.

The experiments used a proton exchange membrane electrolyser.

Carbon dioxide flowed into an electrochemical cell and was converted into formic acid, just like charging a battery.

Read more at Science Daily

What turned Earth into a giant snowball 700m years ago? Scientists now have an answer

Australian geologists have used plate tectonic modelling to determine what most likely caused an extreme ice-age climate in Earth's history, more than 700 million years ago.

The study, published in Geology, helps our understanding of the functioning of the Earth's built-in thermostat that prevents the Earth from getting stuck in overheating mode.

It also shows how sensitive global climate is to atmospheric carbon concentration.

"Imagine the Earth almost completely frozen over," said the study's lead author, ARC Future Fellow Dr Adriana Dutkiewicz.

"We now think we have cracked the mystery: historically low volcanic carbon dioxide emissions, aided by weathering of a large pile of volcanic rocks in what is now Canada; a process that absorbs atmospheric carbon dioxide."

The project was inspired by the glacial debris left by the ancient glaciation from this period that can be spectacularly observed in the Flinders Ranges in South Australia.

A recent geological field trip to the Ranges, led by co-author Professor Alan Collins from the University of Adelaide, prompted the team to use the University of Sydney EarthByte computer models to investigate the cause and the exceptionally long duration of this ice age.

The extended ice age, also called the Sturtian glaciation after the 19th century European colonial explorer of central Australia, Charles Sturt, stretched from 717 to 660 million years ago, a period well before the dinosaurs and complex plant life on land existed.

Dr Dutkiewicz said: "Various causes have been proposed for the trigger and the end of this extreme ice age, but the most mysterious aspect is why it lasted for 57 million years -- a time span hard for us humans to imagine."

The team went back to a plate tectonic model that shows the evolution of continents and ocean basins at a time after the breakup of the ancient supercontinent Rodina.

They connected it to a computer model that calculates CO2 degassing of underwater volcanoes along mid-ocean ridges -- the sites where plates diverge and new ocean crust is born.

They soon realised that the start of the Sturtian ice age precisely correlates with an all-time low in volcanic CO2 emissions.

In addition, the CO2 outflux remained relatively low for the entire duration of the ice age.

Dr Dutkiewicz said: "At this time, there were no multicellular animals or land plants on Earth. The greenhouse gas concentration of the atmosphere was almost entirely dictated by CO2 outgassing from volcanoes and by silicate rock weathering processes, which consume CO2."

Co-author Professor Dietmar Müller from the University of Sydney said: "Geology ruled climate at this time. We think the Sturtian ice age kicked in due to a double whammy: a plate tectonic reorganisation brought volcanic degassing to a minimum, while simultaneously a continental volcanic province in Canada started eroding away, consuming atmospheric CO2.

"The result was that atmospheric CO2 fell to a level where glaciation kicks in -- which we estimate to be below 200 parts per million, less than half today's level."

The team's work raises intriguing questions about Earth's long-term future.

A recent theory proposed that over the next 250 million years, Earth would evolve towards Pangea Ultima, a supercontinent so hot that mammals might become extinct.

However, the Earth is also currently on a trajectory of lower volcanic CO2 emissions, as continental collisions increase and the plates slow down.

Read more at Science Daily

Ice age could help predict oceans' response to global warming

A team of scientists led by a Tulane University oceanographer has found that deposits deep under the ocean floor reveal a way to measure the ocean oxygen level and its connections with carbon dioxide in the Earth's atmosphere during the last ice age, which ended more than 11,000 years ago.

The findings, published in Science Advances, help explain the role oceans played in past glacial melting cycles and could improve predictions of how ocean carbon cycles will respond to global warming.

Oceans adjust atmospheric CO2 as ice ages transition to warmer climates by releasing the greenhouse gas from carbon stored within the deep ocean.

The research demonstrates a striking correlation between global ocean oxygen contents and atmospheric CO2 from the last ice age to today -- and how carbon release from the deep sea may rise as the climate warms.

"The research reveals the important role of the Southern Ocean in controlling the global ocean oxygen reservoir and carbon storage," said Yi Wang, lead researcher and an assistant professor of Earth and Environmental Sciences at Tulane University School of Science and Engineering.

Wang specializes in marine biogeochemistry and paleoceanography.

"This will have implications for understanding how the ocean, especially the Southern Ocean, will dynamically affect the atmospheric CO2 in the future," she said.

Wang conducted the study with colleagues from the Woods Hole Oceanographic Institution, the world's leading independent nonprofit organization dedicated to ocean research, exploration and education.

She worked for the institute before joining Tulane in 2023.

The team analyzed seafloor sediments collected from the Arabian Sea to reconstruct average global ocean oxygen levels thousands of years ago.

They precisely measured isotopes of the metal thallium trapped in the sediments, which indicate how much oxygen was dissolved in the global ocean at the time the sediments formed.

"Study of these metal isotopes on glacial-interglacial transitions has never been looked at before, and these measurements allowed us to essentially recreate the past," Wang said.

The thallium isotope ratios showed the global ocean lost oxygen overall during the last ice age compared to the current warmer interglacial period.

Their study revealed thousand-year global ocean deoxygenation during abrupt warming in the Northern Hemisphere, whereas the ocean gained more oxygen when abrupt cooling occurred during the transition from the last ice age to today.

The researchers attributed the observed ocean oxygen changes to Southern Ocean processes.

"This study is the first to present an average picture of how the oxygen content of the global oceans evolved as Earth transitioned from the last glacial period into the warmer climate of the last 10,000 years," said Sune Nielsen, associate scientist at WHOI and co-author of the research.

Read more at Science Daily

Focus on biological processes does not capture the whole picture

The ocean contains about 60 times more carbon than the atmosphere, in part due to a key process in the marine carbon cycle called the biological carbon pump (BCP). In this process, carbon dioxide (CO2) is converted to organic matter through photosynthesis and subsequently sinks as the so-called "export flux" from the surface ocean waters to the deep sea. As it sinks, bacterial decomposition processes break down the organic matter back into inorganic carbon, thus storing CO2 in the interior ocean. The BCP keeps atmospheric CO2 levels significantly lower than they would be in a hypothetical world without the BCP. So far, so good.

But one crucial aspect is often overlooked, says Dr Ivy Frenger, a climate researcher at the GEOMAR Helmholtz Centre for Ocean Research Kiel: "You have to consider the ocean circulation, because it determines how much of the biologically produced CO2 can actually accumulate in the interior ocean in the long term, isolated from exchange with the atmosphere." Looking at the effect of the BCP only in terms of the export flux is like trying to explain the balance of a bank account by looking only at the deposits.

"But there are gains and losses."

Changes in the BCP are an important research topic in the context of climate change.

Ivy Frenger notes that when considering the impact of the BCP on atmospheric CO2, it is common to focus on the export flux and neglect the ocean circulation.

She and six international colleagues have therefore published an opinion paper entitled "Misconceptions of the marine biological carbon pump in a changing climate: Thinking outside the 'export' box."

In their paper, the scientists aim to address the misconception that there is a direct link between the global export flux -- equivalent to deposits -- and the biogenic storage of CO2 in the ocean, and hence, atmospheric CO2 -- the equivalent to the bank account balance.

"There is no such simple correlation," says Dr Frenger. The "withdrawal" side also needs to be taken into account.

A much simpler and scientifically more accurate approach, she says, would be to directly estimate the CO2 reservoir resulting from biological processes in the interior ocean.

Such an estimate can be made by measuring the oxygen content of the ocean's interior along with its physical state, such as temperature.

Changes in these variables under climate change would also explain a seemingly paradoxical response of the BCP under anthropogenic climate change: Despite a decreasing export flux, carbon storage due to the biological pump in the interior ocean increases.

This is because changes in ocean circulation delay the return of biologically stored carbon from the ocean interior to the surface.

As in the bank account analogy: while the deposits are lower, if the withdrawals are reduced to an even greater extent there will be a net increase.

Accordingly, for climate change, this feedback results in more CO2 being stored in the ocean's interior than would be the case without the biological carbon pump.

Co-author Angela Landolfi remarks: "It is important to note that this effect is small when compared to the continuing massive anthropogenic CO2 emissions from fossil fuels."

Read more at Science Daily

Arctic cold snap transforms into a blessing

A recent cold spell plunged the nation of Korea into a deep freeze, resulting in the closure of 247 national parks, the cancellation of 14 domestic flights, and the scrapping of 107 cruise ship voyages. While the cold snap brought relief by significantly reducing the prevalence of particulate matter obscuring our surroundings, a recent study indicates that, besides diminishing particulate matter, it is significantly contributing to the heightened uptake of carbon dioxide by the East Sea.

According to research conducted by a team of researchers including Professor Kitack Lee from the Division of Environmental Science & Engineering at Pohang University of Science and Technology (POSTECH), and Professor Tongsup Lee and So-Yun Kim from the Department of Oceanography at Pusan National University, the cold atmosphere in the Arctic is influencing the absorption of carbon dioxide by the East Sea.

The research findings were published in Geophysical Research Letters, an international journal by the American Geophysical Union (AGU).

The research team investigated the correlation between the East Sea's surface-deep circulation and its carbon dioxide absorption capacity, drawing insights from observations in 1992, 1999, 2007, and 2019.

During the initial period (1992-1999), the ocean absorbed 20 million tons of carbon dioxide annually.

In the subsequent period (1999-2007), this amount decreased to under 10 million tons per year.

However, in the final period (2007-2019), the carbon dioxide uptake surged to 30 million tons per year.

The team observed that the internal circulation along the East Coast within the East Sea was influenced by the Arctic cold wave.

Cold air from the Arctic infiltrates the East Sea, causing the surface water, laden with carbon dioxide, to become denser.

This process induces vertical ventilation as the water descends into the middle and deep ocean layers.

Consequently, the intensified descent of cold air from the Arctic strengthens the internal circulation, leading to a heightened uptake of carbon dioxide in the East Sea.

Professor Kitack Lee who led the research remarked, " The oceans represent an immense reservoir of carbon dioxide and offer a secure and sustainable avenue for mitigating atmospheric carbon dioxide levels." He further stated, "It is crucial to anticipate the global ocean's capacity for carbon removal as we navigate future climate changes and identify suitable methods to leverage this potential."

In a related development, the team's earlier research uncovered the mechanism through which the ocean absorbs carbon dioxide.

Approximately half of the carbon dioxide generated by human activities remains in the atmosphere with the other half entering marine and terrestrial ecosystems.

With a carbon content 400,000 times greater than that of the atmosphere, the oceans present vast and promising potential for storing carbon dioxide.

Read more at Science Daily

Three proposals from researchers to meet EU climate goals

The EU countries have decided that the EU is to be climate neutral by 2050. By 2030, greenhouse gas emissions must have been reduced by at least 55% compared to 1990. To meet this target, continued vigorous efforts are needed to reduce emissions, but that alone will not be enough. This is the conclusion of seven researchers from Sweden and Germany in an article in the journal Communications Earth & Environment. One of them is Mathias Fridahl, associate professor at the Department of Thematic Studies -- Environmental Change at Linköping University, Sweden.

"We have painted humanity into a corner. It's no longer possible to solve the climate crisis simply by reducing emissions. We also need to clean the atmosphere of carbon dioxide," says Mathias Fridahl.

The problem is that there are currently no incentives for companies and countries to invest in new technologies to remove carbon dioxide.

That is why a change in the EU's climate policy is needed. "There are many technologies that are quite well developed, but which aren't economically viable," says Mathias Fridahl.

He and his colleagues have three proposals that they believe could soon make a difference.

Anyone contributing to the removal of carbon dioxide should be able to get paid for it under the EU emissions trading scheme.

This should only apply to methods that have a long life span, that is, capture linked to the storage of carbon dioxide for thousands of years.

To get the trading scheme up and running, the researchers propose that the EU set up a central bank for carbon dioxide.

The bank would give investors a good price for the carbon dioxide removed from the atmosphere.

In order to maintain the drive to continue reducing emissions at the same time, the proposal is that the bank strongly regulates how removal may be used to compensate for continued emissions.

The bank's financial muscle could come from revenues from carbon tariffs on goods from outside the Union.

To stimulate other measures with a shorter life span, the researchers propose an extension of the EU's land use regulation.

This sets out the measures to remove carbon dioxide that member states are allowed to be credited with when reporting their climate emissions.

Today, there is a limited amount of removal methods in forestry and agriculture.

The researchers contend that if the regulation were extended to more measures, it would encourage countries to invest resources in carbon removal.

The researchers also want the EU to identify which emissions will be very difficult or impossible to do anything about.

Greater clarity would reduce the risk of companies and member states postponing measures in the hope that their emissions will belong to the group that is difficult to tackle.

This would stimulate innovation and efforts to reduce emissions in parallel with initiatives to remove carbon dioxide.

Read more at Science Daily

Geoscientists map changes in atmospheric CO2 over past 66 million years

Today atmospheric carbon dioxide is at its highest level in at least several million years thanks to widespread combustion of fossil fuels by humans over the past couple centuries.

But where does 419 parts per million (ppm) -- the current concentration of the greenhouse gas in the atmosphere -- fit in Earth's history?

That's a question an international community of scientists, featuring key contributions by University of Utah geologists, is sorting out by examining a plethora of markers in the geologic record that offer clues about the contents of ancient atmospheres. Their initial study was published this week in the journal Science, reconstructing CO2 concentrations going back through the Cenozoic, the era that began with the demise dinosaurs and rise of mammals 66 million years ago.

Glaciers contain air bubbles, providing scientists direct evidence of CO2 levels going back 800,000 years, according to U geology professor Gabe Bowen, one of the study's corresponding authors. But this record does not extend very deep into the geological past.

"Once you lose the ice cores, you lose direct evidence. You no longer have samples of atmospheric gas that you can analyze," Bowen said. "So you have to rely on indirect evidence, what we call proxies. And those proxies are tough to work with because they are indirect."

"Proxies" in the geologic record

These proxies include isotopes in minerals, the morphology of fossilized leaves and other lines of geological evidence that reflect atmospheric chemistry. One of the proxies stems from the foundational discoveries of U geologist Thure Cerling, himself a co-author on the new study, whose past research determined carbon isotopes in ancient soils are indicative of past CO2 levels.

But the strength of these proxies vary and most cover narrow slices of the past. The research team, called the Cenozoic CO2 Proxy Integration Project, or CenCO2PIP, and organized by Columbia University climate scientist Bärbel Hönisch, set out to evaluate, categorize and integrate available proxies to create a high-fidelity record of atmospheric CO2.

"This represents some of the most inclusive and statistically refined approaches to interpreting CO2 over the last 66 million years," said co-author Dustin Harper, a U postdoctoral researcher in Bowen's lab. "Some of the new takeaways are we're able to combine multiple proxies from different archives of sediment, whether that's in the ocean or on land, and that really hasn't been done at this scale."

The new research is a community effort involving some 90 scientists from 16 countries. Funded by dozens of grants from multiple agencies, the group hopes to eventually reconstruct the CO2 record back 540 million years to the dawn of complex life.

At the start of the Industrial Revolution -- when humans began burning to coal, then oil and gas to fuel their economies -- atmospheric CO2 was around 280 ppm. The heat-trapping gas is released into the air when these fossil fuels burn.

Looking forward, concentrations are expected to climb up to 600 to 1,000 ppm by the year 2100, depending on the rate of future emissions. It is not clear exactly how these future levels will influence the climate.

But having a reliable map of past CO2 levels could help scientists more accurately predict what future climates may look like, according to U biology professor William Anderegg, director the U's Wilkes Center for Climate & Policy.

"This is an incredibly important synthesis and has implications for future climate change as well, particularly the key processes and components of the Earth system that we need to understand to project the speed and magnitude of climate change," Anderegg said.

Today's 419 ppm is the highest CO2 in 14 million years

At times in the past when Earth was a far warmer place, levels of CO2 were much higher than now. Still, the 419 ppm recorded today represents a steep and perhaps dangerous spike and is unprecedented in recent geologic history.

"By 8 million years before present, there's maybe a 5% chance that CO2 levels were higher than today," Bowen said, "but really we have to go back 14 million years before we see levels we think were like today."

In other words, human activity has significantly altered the atmosphere within the span of a few generations. As a result, climate systems around the globe are showing alarming signs of disruption, such as powerful storms, prolonged drought, deadly heat waves and ocean acidification.

A solid understanding of atmospheric CO2 variation through geological time is also essential to deciphering and learning from various features of Earth's history. Changes in atmospheric CO2 and climate likely contributed to mass extinctions, as well as evolutionary innovations.

Read more at Science Daily

Window to avoid 1.5°C of warming will close before 2030 if emissions are not reduced

Without rapid carbon dioxide emission reductions, the world has a 50% chance of locking in 1.5°C of warming before 2030, according to a study led by Imperial College London researchers.

The study, published today in Nature Climate Change, is the most up-to-date and comprehensive analysis of the global carbon budget. The carbon budget is an estimate of the amount of carbon dioxide emissions that can be emitted while keeping global warming below certain temperature limits.

The Paris Agreement aims to limit global temperature increase to well below 2°C above preindustrial levels and pursue efforts to limit it to 1.5°C. The remaining carbon budget is commonly used to assess global progress against these targets.

The new study estimates that for a 50% chance of limiting warming to 1.5°C, there are less than 250 gigatonnes of carbon dioxide left in the global carbon budget.

The researchers warn that if carbon dioxide emissions remain at 2022 levels of about 40 gigatonnes per year, the carbon budget will be exhausted by around 2029, committing the world to warming of 1.5°C above preindustrial levels.

The finding means the budget is less than previously calculated and has approximately halved since 2020 due to the continued increase of global greenhouse gas emissions, caused primarily from the burning of fossil fuels as well as an improved estimate of the cooling effect of aerosols, which are decreasing globally due to measures to improve air quality and reduce emissions.

Dr Robin Lamboll, research fellow at the Centre for Environmental Policy at Imperial College London, and the lead author of the study, said: "Our finding confirms what we already know -- we're not doing nearly enough to keep warming below 1.5°C.

"The remaining budget is now so small that minor changes in our understanding of the world can result in large proportional changes to the budget. However, estimates point to less than a decade of emissions at current levels.

"The lack of progress on emissions reduction means that we can be ever more certain that the window for keeping warming to safe levels is rapidly closing."

Dr Joeri Rogelj, Director of Research at the Grantham Institute and Professor of Climate Science & Policy at the Centre for Environmental Policy at Imperial College London, said: "This carbon budget update is both expected and fully consistent with the latest UN Climate Report.

"That report from 2021 already highlighted that there was a one in three chance that the remaining carbon budget for 1.5°C could be as small as our study now reports.

"This shows the importance of not simply looking at central estimates, but also considering the uncertainty surrounding them."

The study also found that the carbon budget for a 50% chance of limiting warming to 2°C is approximately 1,200 gigatonnes, meaning that if carbon dioxide emissions continue at current levels, the central 2°C budget will be exhausted by 2046.

There has been much uncertainty in calculating the remaining carbon budget, due to the influence of other factors, including warming from gasses other than carbon dioxide and the ongoing effects of emissions that are not accounted for in models.

The new researchused an updated dataset and improved climate modelling compared to other recent estimates, published in June, characterising these uncertainties and increasing confidence around the remaining carbon budget estimates.

The strengthened methodology also gave new insights into the importance of the potential responses of the climate system to achieving net zero.

'Net zero' refers to achieving an overall balance between global emissions produced and emissions removed from the atmosphere.

According to the modelling results in the study, there are still large uncertainties in the way various parts of the climate system will respond in the years just before net zero is achieved.

It is possible that the climate will continue warming due to effects such as melting ice, the release of methane, and changes in ocean circulation.

However, carbon sinks such as increased vegetation growth could also absorb large amounts of carbon dioxide leading to a cooling of global temperatures before net zero is achieved.

Dr Lamboll says these uncertainties further highlight the urgent need to rapidly cut emissions. "At this stage, our best guess is that the opposing warming and cooling will approximately cancel each other out after we reach net zero.

"However, it's only when we only when we cut emissions and get closer to net zero that we will be able to see what the longer-term heating and cooling adjustments will look like.

Read more at Science Daily

Engineers develop an efficient process to make fuel from carbon dioxide

The search is on worldwide to find ways to extract carbon dioxide from the air or from power plant exhaust and then make it into something useful. One of the more promising ideas is to make it into a stable fuel that can replace fossil fuels in some applications. But most such conversion processes have had problems with low carbon efficiency, or they produce fuels that can be hard to handle, toxic, or flammable.

Now, researchers at MIT and Harvard University have developed an efficient process that can convert carbon dioxide into formate, a liquid or solid material that can be used like hydrogen or methanol to power a fuel cell and generate electricity. Potassium or sodium formate, already produced at industrial scales and commonly used as a de-icer for roads and sidewalks, is nontoxic, nonflammable, easy to store and transport, and can remain stable in ordinary steel tanks to be used months, or even years, after its production.

The new process, developed by MIT doctoral students Zhen Zhang, Zhichu Ren, and Alexander H. Quinn, Harvard University doctoral student Dawei Xi, and MIT Professor Ju Li, is described this week in the journal Cell Press Physical Sciences. The whole process -- including capture and electrochemical conversion of the gas to a solid formate powder, which is then used in a fuel cell to produce electricity -- was demonstrated at a small, laboratory scale. However, the researchers expect it to be scalable so that it could provide emissions-free heat and power to individual homes and even be used in industrial or grid-scale applications.

Other approaches to converting carbon dioxide into fuel, Li explains, usually involve a two-stage process: First the gas is chemically captured and turned into a solid form as calcium carbonate, then later that material is heated to drive off the carbon dioxide and convert it to a fuel feedstock such as carbon monoxide. That second step has very low efficiency, typically converting less than 20 percent of the gaseous carbon dioxide into the desired product, Li says.

By contrast, the new process achieves a conversion of well over 90 percent and eliminates the need for the inefficient heating step by first converting the carbon dioxide into an intermediate form, liquid metal bicarbonate. That liquid is then electrochemically converted into liquid potassium or sodium formate in an electrolyzer that uses low-carbon electricity, e.g. nuclear, wind, or solar power. The highly concentrated liquid potassium or sodium formate solution produced can then be dried, for example by solar evaporation, to produce a solid powder that is highly stable and can be stored in ordinary steel tanks for up to years or even decades, Li says.

Several steps of optimization developed by the team made all the difference in changing an inefficient chemical-conversion process into a practical solution, says Li, who holds joint appointments in the departments of Nuclear Science and Engineering and of Materials Science and Engineering.

The process of carbon capture and conversion involves first an alkaline solution based capture that concentrates carbon dioxide, either from concentrated streams such as from power plant emissions or from very low-concentration sources, even open air, into the form of a liquid metal-bicarbonate solution. Then, through the use of a cation-exchange membrane electrolyzer, this bicarbonate is electrochemically converted into solid formate crystals with a carbon efficiency of greater than 96 percent, as confirmed in the team's lab-scale experiments.

These crystals have an indefinite shelf life, remaining so stable that they could be stored for years, or even decades, with little or no loss. By comparison, even the best available practical hydrogen storage tanks allow the gas to leak out at a rate of about 1 percent per day, precluding any uses that would require year-long storage, Li says. Methanol, another widely explored alternative for converting carbon dioxide into a fuel usable in fuel cells, is a toxic substance that cannot easily be adapted to use in situations where leakage could pose a health hazard. Formate, on the other hand, is widely used and considered benign, according to national safety standards.

Several improvements account for the greatly improved efficiency of this process. First, a careful design of the membrane materials and their configuration overcomes a problem that previous attempts at such a system have encountered, where a buildup of certain chemical byproducts changes the pH, causing the system to steadily lose efficiency over time. "Traditionally, it is difficult to achieve long-term, stable, continuous conversion of the feedstocks," Zhang says. "The key to our system is to achieve a pH balance for steady-state conversion."

To achieve that, the researchers carried out thermodynamic modeling to design the new process so that it is chemically balanced and the pH remains at a steady state with no shift in acidity over time. It can therefore can continue operating efficiently over long periods. In their tests, the system ran for over 200 hours with no significant decrease in output. The whole process can be done at ambient temperatures and relatively low pressures (about five times atmospheric pressure).

Another issue was that unwanted side reactions produced other chemical products that were not useful, but the team figured out a way to prevent these side reactions by the introduction of an extra "buffer" layer of bicarbonate-enriched fiberglass wool that blocked these reactions.

The team also built a fuel cell specifically optimized for the use of this formate fuel to produce electricity. The stored formate particles are simply dissolved in water and pumped into the fuel cell as needed. Although the solid fuel is much heavier than pure hydrogen, when the weight and volume of the high-pressure gas tanks needed to store hydrogen is considered, the end result is an electricity output near parity for a given storage volume, Li says.

The formate fuel can potentially be adapted for anything from home-sized units to large scale industrial uses or grid-scale storage systems, the researchers say. Initial household applications might involve an electrolyzer unit about the size of a refrigerator to capture and convert the carbon dioxide into formate, which could be stored in an underground or rooftop tank. Then, when needed, the powdered solid would be mixed with water and fed into a fuel cell to provide power and heat. "This is for community or household demonstrations," Zhang says, "but we believe that also in the future it may be good for factories or the grid."

Read more at Science Daily