Climate-change-triggered 2023 mega-landslide caused Earth to vibrate for nine days

A landslide in a remote part of Greenland caused a mega-tsunami that sloshed back and forth across a fjord for nine days, generating vibrations throughout Earth, according to a new study involving UCL researchers.

The study, published in the journal Science, concluded that this movement of water was the cause of a mysterious, global seismic signal that lasted for nine days and puzzled seismologists in September 2023.

The initial event, not observed by human eye, was the collapse of a 1.2km-high mountain peak into the remote Dickson Fjord beneath, causing a backsplash of water 200 metres in the air, with a wave up to 110 metres high. This wave, extending across 10km of fjord, reduced to seven metres within a few minutes, the researchers calculated, and would have fallen to a few centimetres in the days after.

The team used a detailed mathematical model, recreating the angle of the landslide and the uniquely narrow and bendy fjord, to demonstrate how the sloshing of water would have continued for nine days, with little energy able to escape.

The model predicted that the mass of water would have moved back and forth every 90 seconds, matching the recordings of vibrations travelling in the Earth's crust all around the globe.

The landslide, the researchers wrote, was a result of the glacier at the foot of the mountain thinning, becoming unable to hold up the rock-face above it. This was ultimately due to climate change. The landslide and tsunami were the first observed in eastern Greenland.

Co-author Dr Stephen Hicks, of UCL Earth Sciences, said: "When I first saw the seismic signal, I was completely baffled. Even though we know seismometers can record a variety of sources happening on Earth's surface, never before has such a long-lasting, globally travelling seismic wave, containing only a single frequency of oscillation, been recorded. This inspired me to co-lead a large team of scientists to figure out the puzzle.

"Our study of this event amazingly highlights the intricate interconnections between climate change in the atmosphere, destabilisation of glacier ice in the cryosphere, movements of water bodies in the hydrosphere, and Earth's solid crust in the lithosphere.

"This is the first time that water sloshing has been recorded as vibrations through the Earth's crust, travelling the world over and lasting several days."

The mysterious seismic signal -- coming from a vibration through the Earth's crust -- was detected by seismometers all over the globe, from the Arctic to Antarctica. It looked completely different to frequency-rich 'rumbles' and 'pings' from earthquake recordings, as it contained only a single vibration frequency, like a monotonous-sounding hum.

When the study's authors first discovered the signal, they made a note of it as a "USO": unidentified seismic object.

At the same time, news of a large tsunami in a remote northeast Greenland fjord reached authorities and researchers working in the area.

The researchers joined forces in a unique multidisciplinary group involving 68 scientists from 40 institutions in 15 countries, combining seismometer and infrasound data, field measurements, on-the-ground and satellite imagery, and simulations of tsunami waves.

The team also used imagery captured by the Danish military who sailed into the fjord just days after the event to inspect the collapsed mountain-face and glacier front along with the dramatic scars left by the tsunami.

It was this combination of local field data and remote, global-scale observations that allowed the team to solve the puzzle and reconstruct the extraordinary cascading sequence of events.

Lead author Dr Kristian Svennevig, from the Geological Survey of Denmark and Greenland (GEUS), said: "When we set out on this scientific adventure, everybody was puzzled and no one had the faintest idea what caused this signal. All we knew was that it was somehow associated with the landslide. We only managed to solve this enigma through a huge interdisciplinary and international effort."

He added: "As a landslide scientist, an additional interesting aspect of this study is that this is the first-ever landslide and tsunami observed from eastern Greenland, showing how climate change already has major impacts there."

The team estimated that 25 million cubic metres of rock and ice crashed into the fjord (enough to fill 10,000 Olympic-sized swimming pools).

They confirmed the size of the tsunami, one of the largest seen in recent history, using numerical simulations as well as local data and imagery.

Seventy kilometres away from the landslide, four-metre-high tsunami waves damaged a research base at Ella Ø (island) and destroyed cultural and archaeological heritage sites across the fjord system.

The fjord is on a route commonly used by tourist cruise ships visiting the Greenland fjords. Fortunately, no cruise ships were close to Dickson Fjord on the day of the landslide and tsunami, but if they had been, the consequences of a tsunami wave of that magnitude could have been devastating.

Mathematical models recreating the width and depth of the fjord at very high resolution demonstrated how the distinct rhythm of a mass of water moving back and forth matched the seismic signal.

The study concluded that with rapidly accelerating climate change, it will become more important than ever to characterise and monitor regions previously considered stable and provide early warning of these massive landslide and tsunami events.

Co-author Thomas Forbriger, from Karlsruhe Institute of Technology, said: "We wouldn't have discovered or been able to analyse this amazing event without networks of high-fidelity broadband seismic stations around the world, which are the only sensors that can truly capture such a unique signal."

 Read more at Science Daily

How El Nino and mega ocean warming caused the greatest-ever mass extinction

Mega ocean warming El Niño events were key in driving the largest extinction of life on planet Earth some 252 million years ago, according to new research.

The study, published today in Science and co-led by the University of Bristol and China University of Geosciences (Wuhan), has shed new light on why the effects of rapid climate change in the Permian-Triassic warming were so devastating for all forms of life in the sea and on land.

Scientists have long linked this mass extinction to vast volcanic eruptions in what is now Siberia. The resulting carbon dioxide emissions rapidly accelerated climate warming, resulting in widespread stagnation and the collapse of marine and terrestrial ecosystems.

But what caused life on land, including plants and usually resilient insects, to suffer just as badly has remained a source of mystery.

Co-lead author Dr Alexander Farnsworth, Senior Research Associate at the University of Bristol, said: “Climate warming alone cannot drive such devastating extinctions because, as we are seeing today, when the tropics become too hot, species migrate to the cooler, higher latitudes. Our research has revealed that increased greenhouse gases don’t just make the majority of the planet warmer, they also increase weather and climate variability making it even more ‘wild’ and difficult for life to survive.”

The Permian-Triassic catastrophe shows the problem of global warming is not just a matter of it becoming unbearably hot, but also a case of conditions swinging wildly over decades.

“Most life failed to adapt to these conditions, but thankfully a few things survived, without which we wouldn’t be here today. It was nearly, but not quite, the end of the life on Earth,” said co-lead author Professor Yadong Sun at China University of Geosciences, Wuhan.

The scale of Permian-Triassic warming was revealed by studying oxygen isotopes in the fossilised tooth material of tiny extinct swimming organisms called conodonts. By studying the temperature record of conodonts from around the world, the researchers were able to show a remarkable collapse of temperature gradients in the low and mid latitudes.

Dr Farnsworth, who used pioneering climate modelling to evaluate the findings, said: “Essentially, it got too hot everywhere. The changes responsible for the climate patterns identified were profound because there were much more intense and prolonged El Niño events than witnessed today. Species were simply not equipped to adapt or evolve quickly enough.”

In recent years El Niño events have caused major changes in rainfall patterns and temperature. For example, the weather extremes that caused the June 2024 North American heatwave when temperatures were around 15°C hotter than normal. 2023-2024 was also one of the hottest years on record globally due to a strong El Niño in the Pacific, which was further exacerbated by increased human-induced CO2 driving catastrophic drought and fires around the world.

“Fortunately such events so far have only lasted one to two years at a time. During the Permian-Triassic crisis, El Niño persisted for much longer resulting in a decade of widespread drought, followed by years of flooding. Basically, the climate was all over the place and that makes it very hard for any species to adapt,” co-author Paul Wignall, Professor of Palaeoenvironments at the University of Leeds.

The results of the climate modelling also help explain the abundant charcoal found in rock layers of that age.

“Wildfires become very common if you have a drought-prone climate. Earth got stuck in a crisis state where the land was burning and the oceans stagnating. There was nowhere to hide,” added co-author Professor David Bond, a palaeontologist at the University of Hull.

The researchers observed that throughout Earth’s history there have been many volcanic events similar to those in Siberia, and many caused extinctions, but none led to a crisis of the scale of the Permian-Triassic event.

They found Permian-Triassic extinction was so different because these Mega-El Niños created positive feedback on the climate which led to incredibly warm conditions starting in the tropics and then beyond, resulting in the dieback of vegetation. Plants are essential for removing CO2 from the atmosphere, as well as the foundation of the food web, and if they die so does one of the Earth's mechanisms to stop CO2 building up in the atmosphere as a result of continued volcanism.

This also helps explain the conundrum regarding the Permian-Triassic mass extinction whereby the extinction on land occurred tens of thousands of years before extinction in the oceans.

“Whilst the oceans were initially shielded from the temperature rises, the mega-El Nino’s caused temperatures on land to exceed most species thermal tolerances at rates so rapid that they could not adapt in time,” explained Dr Sun.

“Only species that could migrate quickly could survive, and there weren’t many plants or animals that could do that.”

Mass extinctions, although rare, are the heartbeat of the Earth’s natural system resetting life and evolution along different paths.

Read more at Science Daily

Coastal cities must adapt faster to climate change

Coastal cities play a key role in the global economy and have important functions for society at large. At the same time, they are severely affected by the impact of climate change. That is why their role in global climate adaptation is crucial. To find out how coastal cities are adapting, an international team led by Professor Matthias Garschagen, a geographer at Ludwig-Maximilians-Universität München (LMU), has now analyzed the current state of adaptation.

Based on studies of 199 cities across 54 countries, the researchers investigated whether and how cities take certain risk factors into account in their adaptation efforts. Climate factors like rising sea levels, storms, flooding and heat were among the key parameters considered. Other aspects were also taken into account in the analysis, such as the exposure and vulnerability of the population, the infrastructure and the ecosystems in the respective region.

Climate measures are mostly inadequate

Most of the measures taken to adapt to climate change relate primarily to sea level rise, flooding and, to a lesser extent, storm surges, cyclones and erosion. Technical and institutional measures such as large-scale levees or urban planning innovations are more common in wealthier regions like North America and Europe. In less prosperous regions such as in many parts of Africa and Asia, behavior-related measures are the dominant type, with affected households and companies being largely left to their own devices.

Overall, the LMU researchers found that most adaptation measures are inadequate in their depth, scope and speed -- regardless of the region or its prosperity. The researchers also found little evidence of a sustainable reduction in risk as a result of the measures taken.

"Our findings reveal that there is plenty of work still to be done on all levels," explains Prof. Matthias Garschagen. "There has been little truly far-reaching change involving a fundamental rethink of risk management. Cities often attempt to optimize their disaster management on the basis of past experience without fundamentally questioning whether these approaches are still going to be viable in the future," says Garschagen.

Global research on climate change needs to be done in all regions of the world

The research also found that it is rare for adaptation planning to be based on quantifiable factors. Although cities do take future natural risks such as flooding and heat into account, they rarely consider socioeconomic factors such as future trends in societal vulnerability or spatial growth and exposure. "But those trends those are important," says Garschagen, "because the Lagos or Jakarta of today is not the same as it's going to be in 20 years' time. There are certainly big research aps and we need better scenarios and better modeling methods. Another important question is about when it makes more sense to abandon coastal protection measures and consider resettling the population instead."

Read more at Science Daily

Detecting climate change using aerosols

Researchers analyzed long-term aerosol satellite observation big data focusing on the Pacific Ocean downwind of China. Using a newly developed metric that considered aerosols as tracers, they detected altered atmospheric transport patterns associated with climate change. They observed that the distance of transboundary air pollution moving east from China had shortened. Thus, long-term satellite-based Earth observations are crucial for early climate change detection and accurate evaluation of this trend.

Climate change is one of the most significant environmental challenges of present times, leading to extreme weather events, including droughts, forest fires, and floods. The primary driver for climate change is the release of greenhouse gases into the atmosphere due to human activities, which trap heat and raise Earth's temperature. Aerosols (such as particulate matter, PM2.5) not only affect public health but also influence the Earth's climate by absorbing and scattering sunlight and altering cloud properties. Although future climate change predictions are being reported, it is possible that the impacts of climate change could be more severe than predicted. Therefore, it is necessary to detect climate change accurately and as early as possible.

Building on these insights, a research team from Japan, led by Professor Hitoshi Irie from the Center for Environmental Remote Sensing at Chiba University, utilized long-term observational data to study the effect of climate change on transboundary air pollution in the downwind area of China by using aerosols. They utilized a completely unique perspective on how aerosols impact climate and developed a new metric to detect climate change by considering aerosols as tracers.

"The significance of this study lies in the fact that most of its results are derived from observational data. In natural sciences focused on Earth studies, the ultimate goal is to piece together highly accurate data obtained from observations to quantitatively understand the processes occurring on Earth and to pursue immutable truths. Therefore, the more observational data we have, the better. With the continued Earth observations by Japan's major Earth observation satellites (such as the GCOM series, GOSAT series, Himawari series, and ALOS series), we aim to complement these efforts with numerical simulations and data science methodologies to achieve a safe and secure global environment that mitigates the impacts of the climate crisis." explains Prof. Irie.

The research team included Ms. Ying Cai from the Graduate School of Science and Engineering, Chiba University, Dr. Alessandro Damiani from the Center for Climate Change Adaptation, National Institute for Environmental Studies, Dr. Syuichi Itahashi and Professor Toshihiko Takemura from the Research Institute for Applied Mechanics, Kyushu University, and Dr. Pradeep Khatri from Faculty of Science and Engineering, Soka University. Their study was made available online on May 23, 2024, and published in Science of The Total Environment on August 20, 2024.

China is a major contributor to air pollution in East Asia. The downwind area of China analyzed in this study is a unique open ocean area with minimal human interference yet an important zone of transboundary air pollution pathways, making it an ideal location for studying meteorological variations due to climate change.

In their study, the researchers analyzed aerosol optical depth (AOD) datasets derived from satellites, reanalysis datasets, and numerical simulations focused on the Pacific Ocean in the downwind area of China, over 19 years from 2003 to 2021. AOD, a measure of the amount of sunlight blocked by aerosols, is a key factor is analyzing aerosols and their impact on climate change.

The researchers developed a new metric called RAOD which utilized the potential of aerosols as tracers to evaluate the impact of climate change on transboundary air pollution pathways. Using RAOD the researchers were able to quantify significant temporal variations in aerosol transport. They discovered that long-term changes in RAOD due to climate change were outweighed by larger year-to-year variations in the meteorological field. Moreover, seasonal trends showed that aerosols moved west to east during spring and winter, and northward in summer. They concluded that the probability of aerosols from China to be transported far eastward was low, highlighting a shift in transboundary pollution pathways due to global warming. In this study the authors successfully detected climate change using long-term satellite observational data, in contrast to most existing studies that tracked transboundary air pollution using model simulations.

"These results suggest that RAOD is a valuable metric for quantifying the long-term changes in transboundary air pollution pathways due to climate change. These results are particularly significant because most of them are derived from observational data," says Prof. Irie, highlighting the importance of the study. Sharing the future implications of their study he concludes, "The effects of climate change could be more severe than currently predicted. This study will help verify climate change predictions from an unconventional perspective of 'aerosol observation,' enabling a more accurate understanding of climate change progression and implementation of rational countermeasures."

Read more at Science Daily

Antarctic-wide survey of plant life to aid conservation efforts

The first continent-wide mapping study of plant life across Antarctica reveals growth in previously uncharted areas and is set to inform conservation measures across the region.

The satellite survey of mosses, lichens and algae across the continent will form a baseline for monitoring how Antarctica's vegetation responds to climate change.

Scientists used a European Space Agency satellite to sweep the continent, combined with field measurements taken over several summer seasons, and detected almost 45 square kilometers of vegetation -- roughly three times the size of Lake Windermere in the Lake District, UK.

The international team, led by the University of Edinburgh with the Norwegian Institute for Nature Research, British Antarctic Survey and Scottish Association for Marine Science, found that over 80 per cent of the vegetation growth was contained within the Antarctic Peninsula and neighbouring islands.

The team estimates this growth makes up only 0.12 percent of Antarctica's total ice-free area, highlighting the importance of monitoring key areas of vegetation abundance, which is inadequately protected under the existing Antarctic Specially Protected Area (ASPA) system, experts say.

Antarctic vegetation, dominated by mosses and lichens, has adapted to survive the harsh polar conditions and each type plays an important role in carbon and nutrient recycling on a local level, experts say.

Until now, their spatial coverage and abundance across the continent remained unknown.

Previous research has shown that the environmental sensitivity of Antarctica's vegetative species makes them excellent barometers of regional climate change.

Monitoring their presence in Antarctica, a minimally disturbed landscape, could provide clues as to how similar vegetation types may respond to climate in other fragile ecosystems across the globe, such as parts of the Arctic.

Charlotte Walshaw, PhD researcher from the School of GeoSciences, University of Edinburgh, who led the study, said: "Our continent-scale map provides key information on vegetation presence in areas that are rarely visited by people. This will have profound implications for our understanding of where vegetation is located across the continent, and what factors influence this distribution."

Dr Claudia Colesie, researcher at the University of Edinburgh's School of GeoSciences, who took part in the study, said: "Lichens and mosses in Antarctica encounter the harshest living conditions on the planet on a daily basis. Only the most resilient organisms can thrive there. Now that we know where to look for them, we can provide more targeted conservation measures to safeguard their future."

Read more at Science Daily

Scientists and climate change: Extreme concern and high level of engagement

Scientists from across academic disciplines are extremely concerned about climate change. Many of them have already changed their own lifestyles or engaged in advocacy and protest, with even more being willing to do so in future. This is evident from a large-scale survey of scientists from all over the world, conducted by an international research team led by the University of Amsterdam. The researchers not only looked at the views of scientists and the extent to which they are engaged in climate action, but also at how the involvement of scientists with climate change can be increased. The research was published on Monday, 5 August, in the journal Nature Climate Change.

'Climate change is an existential threat to humanity,' says postdoctoral researcher Fabian Dablander of the UvA's Institute for Biodiversity and Ecosystem Dynamics and one of the lead authors of the study. 'To secure a liveable future, each of us needs to ask ourselves: how can I best contribute at this crucial moment in human history? Scientists are well placed to help tackle climate change beyond conducting academic research. However, little is known about their wider engagement with the issue. Hence our study, in which we conducted quantitative and qualitative analyses of a survey of over 9,000 researchers from all scientific disciplines, not just climate science.'

Fundamental and personal

Most respondents (83%) in the survey say they are 'quite a bit' or 'a great deal' worried about climate change. The vast majority (91%) of them believe that fundamental changes in social, political and economic systems are needed to truly tackle climate change. Most respondents (84%) also think that significant changes in personal behaviour and lifestyle are needed. Many of them say they have already made significant changes to their lifestyle, by driving less (69%), flying less (51%) and switching to a more plant-based diet (39%).

Willingness to engage

A majority of scientists in the survey believe that climate activist groups can bring about positive change and that scientists should be more engaged in climate advocacy and even protest. A significant proportion of respondents are already engaged in climate advocacy (29%), have participated in legal protest (23%) and/or have even engaged in civil disobedience (10%), and about half say they would be willing to engage in some of these in the future.

Breaking down barriers

Based on the data, Dablander and colleagues then looked at which factors predict scientists' engagement in advocacy and protest. They propose a two-step model of engagement. First, in order for scientists to be willing to engage, they need to overcome mostly intellectual barriers such as a lack of belief in the effectiveness of the actions, lack of identification with activists, lack of knowledge, fear of losing credibility, and fear of repercussions. Second, to actually engage they need to overcome mostly practical barriers such as a perceived lack of skills, lack of time, lack of opportunities, and not knowing any groups involved in climate action.

Based on their two-step model, the researchers propose ways to increase scientists' engagement, such as facilitating interactions between scientists who are already engaged and those who are not, and making institutional reforms, for example by offering more time and money for climate-related actions or rewarding public engagement.

Wake-up call

'Governments and corporations continue to make empty promises that downplay the level of transformation that is required to prevent climate breakdown,' says Adam Aron, professor of psychology at the University of California, San Diego, and a co-author of the study: 'This study makes clear that scientists from all disciplines are very worried and are calling for this fundamental transformation. I hope it helps wake people up and get engaged -- more and more scientists are.'

Read more at Science Daily

Local food production saves costs and carbon

Emphasizing local food production over imported substitutes can lead to significant cost and carbon savings, according to data from the Inuvialuit Settlement Region in the Canadian Arctic. The research, conducted by the Max Planck Institute for Evolutionary Anthropology and the Inuvialuit Regional Corporation, shows potential annual savings of more than 3.1 million Canadian dollars and roughly half the carbon emissions when locally harvested food is used instead of imported food. The study underscores the importance of climate change policies that take local food systems into account. Weakening of these local systems could lead to increased emissions and jeopardize the health and food security of remote communities.

Local foods are critical to the food security and health of Indigenous peoples around the world, but local "informal" economies are often invisible in official economic statistics. Consequently, these economies may be overlooked in the policies designed to combat climate change. For instance, Indigenous communities in the North American Arctic are characterized by mixed economies featuring hunting, fishing, gathering and trapping activities, alongside the formal wage economy. The region is also undergoing a rapid transformation due to social, economic and climatic changes. In Canada, the introduction of carbon taxation has implications for the cost of fuel utilized in local food harvesting.

As a first step in understanding the sensitivity of Arctic food systems to carbon tax policy, researchers from the Max Planck Institute for Evolutionary Anthropology, in collaboration with the Innovation, Inuvialuit Science, and Climate Change Division of the Inuvialuit Regional Corporation, attempted to estimate the economic and environmental importance of local food production in the Inuvialuit Settlement Region in the western Canadian Arctic. To do this, the authors utilized data from a regional study of harvesting conducted in 2018, aiming to calculate the total edible weight of food produced by Inuit harvesters within a one-year timeframe.

Reducing CO2 emissions requires locally-adapted policy

The authors then calculated what it would cost to replace these foods with market substitutes, like beef, pork, chicken or farmed fish. They then gathered data from agriculture and transport science to estimate the carbon emissions associated with producing and shipping market substitutes to Arctic communities. Finally, using data from a community-based study of Inuit harvesting in one community in the Inuvialuit Settlement Region (Ulukhaktok), the research team was able to estimate the amount of gasoline used per kilogram of food harvested, and used this information to infer the total amount of gasoline used in local food production in the region.

The resulting estimates suggest that, under plausible scenarios, replacing locally-harvested foods in the Inuvialuit Settlement Region with imported market substitutes would cost over 3.1 million Canadian dollars per year and emit over 1,000 tonnes of CO2-equivalent emissions per year. In contrast, gasoline inputs to local harvesting cost approximately 295,000 Canadian dollars and result in 317 to 496 tonnes of emissions, less than half of what would be emitted by market substitutes. "Our findings illustrate how local food harvesting, even when reliant on fossil fuels -- as is the case in Canadian Arctic communities -- are more economically-efficient and less carbon intensive than industrial food production," says first author Elspeth Ready, a researcher at the Max Planck Institute for Evolutionary Anthropology. "Local food harvesting also reduces reliance on supply chains that are vulnerable to climate change."

Read more at Science Daily

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.

Read more at Science Daily

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

Agriculture: Less productive yet more stable pastures

Climate change will have a considerable influence on the biodiversity and productivity of meadows and pastures. However, according to the results of the large-scale climate and land use experiment, GCEF, which has been conducted at the Helmholtz Centre for Environmental Research (UFZ) for 10 years, the extent of these changes depends on the land use. Grassland optimised for high yield responds much more sensitively to periods of drought than less intensively used meadows and pastures. According to an article recently published in Global Change Biology, this can certainly have economic consequences for the farmers affected.

Grassland is one of the most important and most widespread ecosystems on earth. Such open landscapes with grasses and herbs not only cover more than one quarter of the entire land surface but also store at least one third of the terrestrial carbon, are crucial for food production, and can be extremely species-rich in a relatively small area. But what is the future of these habitats? The study provides new insights into this question.

It has long been clear that two environmental changes are threatening the world's grasslands. Particularly in Europe, grasslands are now fertilised much more heavily, mowed more frequently, and grazed more intensively. In addition, farmers often sow only a handful of grass varieties that promise a particularly high yield. This intensification of land use is fundamentally changing the species composition and functionality of meadows and pastures. The same applies to climate change. For Germany, climate change will result in a shift in the seasonal distribution of precipitation as well as an increase in hydrological extremes (e.g. heavy rainfall and droughts), among other things. It is considered the second largest threat for these ecosystems.

When both changes come together, they can reinforce each other. However, nobody yet knows exactly what will happen. Most experiments on this topic have so far focussed on either the climate or land use. "What makes our study unique is that we investigated the interaction of both factors," explains Dr Lotte Korell, biologist at the UFZ and first author of the publication.

This was made possible by the large-scale and long-term experiment of the UFZ in Bad Lauchstädt near Halle, the Global Change Experimental Facility (GCEF). It consists of 50 plots, each measuring 16 × 24 m; these are used with varying degrees of land use intensity. Temperatures and precipitation levels can also be manipulated with the help of mobile roof systems. For example, some plots receive 10% more precipitation in spring and autumn and 20% less in summer than the untreated control plots. This roughly corresponds to the conditions that climate models project for central Germany.

An eight-year data series from this experiment has now been compiled for the new study. The researchers analysed the biodiversity and productivity of the plants on the differently used plots between 2015 and 2022. "This period includes three of the driest years this region has experienced since beginning of records," recalls Korell. These droughts apparently had a much stronger effect on the plants than the experimentally simulated climate change.

However, in both cases, the trend pointed in the same direction: species-rich grassland that is only rarely mown or sparsely grazed withstood the heat and drought much better than the intensively used high-performance meadows. "Among other factors, this is probably related to the diversity of species," says Korell. This varied greatly depending on the land use of the grasslands.

A diverse mixture of more than 50 native grasses and herbs grew on the less intensively used meadows and pastures of the GCEF. However, on the intensively used grassland, the UFZ team had sown only the five grass varieties recommended to farmers by the Saxony-Anhalt State Institute for Agriculture and Horticulture for drier sites at the start of the experiment. These included varieties of meadow grass (Dactylis glomerata) and perennial ryegrass (Lolium perenne).

Because such grasses are bred for maximum yield and were also heavily fertilised -- as is common in agricultural practice -- the intensive meadows were initially much more productive than the more diverse grasslands. However, they were able to make use of this advantage only in favourable climatic conditions and were not able to withstand the drought as well as the plants in the low-intensity meadows and pastures. In times of drought, the grasses in the intensively used meadows increasingly died back and were replaced by other species such as chickweed (Stellaria media), shepherd's purse (Capsella bursa-pastoris), dandelion (Taraxacum officinale), and small-flowered cranesbill (Geranium pusillum). "These are mostly short-lived species that survive as seeds," explains Dr Harald Auge, also a biologist at the UFZ and senior author of the study. When the more competitive plants succumb to drought, these species take the opportunity to invade their habitats: they either migrate from the low-intensity grassland or germinate from the seed stock in the soil.

This shift in species composition is not particularly welcomed by farmers, especially because most of the new arrivals have a lower fodder quality than the grasses originally sown. The common ragwort (Senecio vulgaris), which was frequently represented among the immigrating species in the experiment, is in fact poisonous. All of this reduces the productivity of the land.

Farmers have long been aware of this kind of degradation of high-performance grassland by immigrating species. They therefore expect to have to plough up and reseed their land every few years. "However, climate change may accelerate this need and lead to additional costs," says Korell. Perhaps everything will go well for a few years and it will rain enough. However, it is also possible that several dry summers will follow one another. Climate change is making conditions even more unpredictable.

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Nature-based solutions to disaster risk from climate change are cost effective

A new global assessment of scientific literature led by researchers at the University of Massachusetts Amherst finds that nature-based solutions (NbS) are an economically effective method to mitigate risks from a range of disasters -- from floods and hurricanes to heatwaves and landslides -- which are only expected to intensify as Earth continues to warm.

NbS are interventions where an ecosystem is either preserved, sustainably managed or restored to provide benefits to society and to nature. For instance, they can mitigate risk from a natural disaster, or facilitate climate mitigation and adaptation. NbS have emerged in combination with or as an alternative to engineering-based solutions. A classic example is restoring wetlands to address coastal flooding rather than constructing a seawall.

"Nature-based solutions are now recognized by major national policies and international global framework agreements to combat climate change, including those drafted by the U.N. and the White House. However, there has been limited scientific knowledge about the cost-effectiveness and equity outcomes of NbS," says Marta Vicarelli, assistant professor of economics and public policy at UMass Amherst and the study's lead author. "Our results indicate that not only are NbS economically effective in mitigating hazards, but that their benefits are still underestimated."

NbS were proven to be a consistently cost-effective approach to mitigating hazards in 71% of the more than 20,000 English-language peer-reviewed studies that researchers examined for the article, which is published in Science of the Total Environment. Another 24% of the studies found NbS to be cost effective under certain conditions. The ecosystem-based interventions most frequently found effective in mitigating hazards are associated with mangroves (80%), forests (77%) and coastal ecosystems (73%).

Of the studies that compared NbS with engineering-based solutions, 65% found the former always to be more effective at mitigating hazards and 24% partially more effective. No study found NbS consistently less effective than engineering solutions.

While every study reviewed for the article examined the hazard-mitigation benefits of NbS, many did not consider added environmental and socioeconomic benefits, such as maintaining biodiversity, climate mitigation and supporting underserved communities.

"The other benefits of NbS are vastly underestimated because they are difficult to quantify," Vicarelli explains. "How should we value improvements in air quality or in soil quality? How should we value the protection of an endangered species or the overall increase in biodiversity after the implementation of an NbS? And how about estimating the cultural or even spiritual value of an environmental asset? These assessments require complex and potentially expensive valuation techniques. For this reason, the additional benefits of NbS are often understudied and underestimated."

Another key finding of the research is that NbS have been financed mainly by the public sector, even when the interventions involve private property. For these solutions to have a truly global impact, additional funding is required, and a significant share must come from the private sector, Vicarelli says.

"A transformative upscaling of Nature-based Solutions requires both public and private financing," she adds. "The next step is developing innovative nature-based insurance and investment solutions."

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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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How can forests be reforested in a climate-friendly way?

Europe's forests have already been severely affected by climate change. Thousands of hectares of trees have already died due to drought and bark beetles. Scientists from the University of Vienna and the Technical University of Munich TUM have now investigated which trees can be used for reforestation. Their findings: only a few tree species are fit for the future, such as English oak in the UK. However, mixed forests are important for the survival of forests, otherwise the forest ecosystem as a whole could be weakened. The results of the study were recently published in the renowned journal Nature Ecology and Evolution.

Although European forests are naturally home to a mix of trees, the number of tree species is lower than in climatically comparable areas of North America or East Asia. In the future, even fewer species will be available to the forestry industry, as scientists led by Johannes Wessely and Stefan Dullinger from the University of Vienna have shown in their new study. Depending on the region, between a third and a half of the tree species found there today will no longer be able to cope with future conditions. "This is an enormous decline," says lead author Johannes Wessely, "especially when you consider that only some of the species are of interest for forestry."

The scientists examined the 69 more common of the just over 100 European tree species with regard to the 21st century in Europe. On average, only nine of these 69 species per location are fit for the future in Europe, compared to four in the UK. "Trees that are planted now for reforestation must survive under both current and future conditions. This is difficult because they have to withstand the cold and frost of the next few years as well as a much warmer climate at the end of the 21st century. There is only a very small overlap," says Wessely. In the UK, these climate-fit species include, for example, the English oak. Which tree species will suit which region of Europe in the future varies greatly overall.

Forest ecosystem at risk due to restriction of species

However, even with the selected set of future-proof trees, a major problem remains: the average of nine species is not enough for a species-rich mixed forest. "Mixed forests consisting of many tree species are an important measure to make forests more robust against disturbances such as bark beetles. In some places in Europe, however, we could run out of tree species to establish such colorful mixed forests," explains last author Rupert Seidl from the Technical University of Munich TUM.

Not all trees offer important properties

Trees store carbon, provide a habitat or food source for animals or can be processed into timber -- these are all important properties of forests. But not all trees fulfill these functions equally; only an average of three of the nine climate-fit tree species can do this.

"Our work clearly shows how severely the vitality of forests is affected by climate change. We cannot rely solely on a new mix of tree species; rapid measures to mitigate climate change are essential for the sustainable protection of our forests," says Wessely.

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Herring arrives earlier in the Wadden Sea due to climate change

Due to the changing climate, young herring arrive in the Wadden Sea earlier and earlier in spring. That is shown in a new publication by NIOZ ecologists Mark Rademaker, Myron Peck and Anieke van Leeuwen, in this month's journal Global Change Biology. "The fact that we were able to demonstrate this, was only due to very consistently, for more than 60 years, and continuously sampling the fish every spring and every fall with exactly the same fyke every time," Rademaker says. "Recognizing this kind of change requires extreme precision and endurance!"

NIOZ fyke

Since 1960, NIOZ, Royal Netherlands Institute for Sea Research, has been measuring the number and species of fish that swim in the Marsdiep, between Den Helder and Texel, day in and day out using a standard fyke, in spring and fall. These measurements show that the peak of the number of young herring swimming into the Wadden Sea since 1982 comes at least two weeks earlier now. "Such a calculation is difficult with a species of fish that swims in large schools," Rademaker says. "One day there may be only ten herring, while the next there are suddenly ten thousand fish swimming by. So, if you were to accidentally take a measurement just one day or the other, you would get a completely different picture."

Extremely consistent measurement

According to Rademaker, the solution to that problem lies in extremely consistent measurement, almost to the square meter. "Only by carrying out measurements in the same place over and over again, and almost continuously, year after year, can you reliably reveal changes in the long term."

Unique set of data

The research with the 'NIOZ fyke' is unique in the world. Most other monitoring programs measure only once or a few times per month or even per quarter, and then often not even at exactly the same spot. Rademaker: "When I projected that frequency from other research programs onto the data from the NIOZ fyke, picking out a few random measurement days, the changes in the timing of the herring did not show up."

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Climate change could become the main driver of biodiversity decline by mid-century

Global biodiversity has declined between 2% and 11% during the 20th century due to land-use change alone, according to a large multi-model study published in Science. Projections show climate change could become the main driver of biodiversity decline by the mid-21st century.

The analysis was led by the German Centre for Integrative Biodiversity Research (iDiv) and the Martin Luther University Halle-Wittenberg (MLU) and is the largest modelling study of its kind to date. The researchers compared thirteen models for assessing the impact of land-use change and climate change on four distinct biodiversity metrics, as well as on nine ecosystem services.

GLOBAL BIODIVERSITY MAY HAVE DECLINED BY 2% TO 11% DUE TO LAND-USE CHANGE ALONE

Land-use change is considered the largest driver of biodiversity change, according to the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES). However, scientists are divided over how much biodiversity has changed in past decades. To better answer this question, the researchers modelled the impacts of land-use change on biodiversity over the 20th century. They found global biodiversity may have declined by 2% to 11% due to land-use change alone. This span covers a range of four biodiversity metrics1 calculated by seven different models.

"By including all world regions in our model, we were able to fill many blind spots and address criticism of other approaches working with fragmented and potentially biased data," says first author Prof Henrique Pereira, research group head at iDiv and MLU. "Every approach has its ups and downsides. We believe our modelling approach provides the most comprehensive estimate of biodiversity trends worldwide."

MIXED TRENDS FOR ECOSYSTEM SERVICES

Using another set of five models, the researchers also calculated the simultaneous impact of land-use change on so-called ecosystem services, i.e., the benefits nature provides to humans. In the past century, they found a massive increase in provisioning ecosystem services, like food and timber production. By contrast, regulating ecosystem services, like pollination, nitrogen retention, or carbon sequestration, moderately declined.

CLIMATE AND LAND-USE CHANGE COMBINED MIGHT LEAD TO BIODIVERSITY LOSS IN ALL WORLD REGIONS

The researchers also examined how biodiversity and ecosystem services might evolve in the future. For these projections, they added climate change as a growing driver of biodiversity change to their calculations.

Climate change stands to put additional strain on biodiversity and ecosystem services, according to the findings. While land-use change remains relevant, climate change could become the most important driver of biodiversity loss by mid-century. The researchers assessed three widely-used scenarios -- from a sustainable development to a high emissions scenario. For all scenarios, the impacts of land-use change and climate change combined result in biodiversity loss in all world regions.

While the overall downward trend is consistent, there are considerable variations across world regions, models, and scenarios.

PROJECTIONS ARE NOT PREDICTIONS

"The purpose of long-term scenarios is not to predict what will happen," says co-author Dr Inês Martins from the University of York. "Rather, it is to understand alternatives, and therefore avoid these trajectories, which might be least desirable, and select those that have positive outcomes. Trajectories depend on the policies we choose, and these decisions are made day by day." Martins co-led the model analyses and is an alumna of iDiv and MLU.

The authors also note that even the most sustainable scenario assessed does not deploy all the policies that could be put in place to protect biodiversity in the coming decades. For instance, bioenergy deployment, one key component of the sustainability scenario, can contribute to mitigating climate change, but can simultaneously reduce species habitats. In contrast, measures to increase the effectiveness and coverage of protected areas or large-scale rewilding were not explored in any of the scenarios

MODELS HELP IDENTIFY EFFECTIVE POLICIES

Assessing the impacts of concrete policies on biodiversity helps identify those policies most effective for safeguarding and promoting biodiversity and ecosystem services, according to the researchers. "There are modelling uncertainties, for sure," Pereira adds. "Still, our findings clearly show that current policies are insufficient to meet international biodiversity goals. We need renewed efforts to make progress against one of the world's largest problems, which is human-caused biodiversity change."

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How light can vaporize water without the need for heat

It's the most fundamental of processes -- the evaporation of water from the surfaces of oceans and lakes, the burning off of fog in the morning sun, and the drying of briny ponds that leaves solid salt behind. Evaporation is all around us, and humans have been observing it and making use of it for as long as we have existed.

And yet, it turns out, we've been missing a major part of the picture all along.

In a series of painstakingly precise experiments, a team of researchers at MIT has demonstrated that heat isn't alone in causing water to evaporate. Light, striking the water's surface where air and water meet, can break water molecules away and float them into the air, causing evaporation in the absence of any source of heat.

The astonishing new discovery could have a wide range of significant implications. It could help explain mysterious measurements over the years of how sunlight affects clouds, and therefore affect calculations of the effects of climate change on cloud cover and precipitation. It could also lead to new ways of designing industrial processes such as solar-powered desalination or drying of materials.

The findings, and the many different lines of evidence that demonstrate the reality of the phenomenon and the details of how it works, are described in the journal PNAS, in a paper by Carl Richard Soderberg Professor of Power Engineering Gang Chen, postdocs Guangxin Lv and Yaodong Tu, and graduate student James Zhang.

The authors say their study suggests that the effect should happen widely in nature -- everywhere from clouds to fogs to the surfaces of oceans, soils, and plants -- and that it could also lead to new practical applications, including in energy and clean water production. "I think this has a lot of applications," Chen says. "We're exploring all these different directions. And of course, it also affects the basic science, like the effects of clouds on climate, because clouds are the most uncertain aspect of climate models."

A newfound phenomenon

The new work builds on research reported last year, which described this new "photomolecular effect" but only under very specialized conditions: on the surface of specially prepared hydrogels soaked with water. In the new study, the researchers demonstrate that the hydrogel is not necessary for the process; it occurs at any water surface exposed to light, whether it's a flat surface like a body of water or a curved surface like a droplet of cloud vapor.

Because the effect was so unexpected, the team worked to prove its existence with as many different lines of evidence as possible. In this study, they report 14 different kinds of tests and measurements they carried out to establish that water was indeed evaporating -- that is, molecules of water were being knocked loose from the water's surface and wafted into the air -- due to the light alone, not by heat, which was long assumed to be the only mechanism involved.

One key indicator, which showed up consistently in four different kinds of experiments under different conditions, was that as the water began to evaporate from a test container under visible light, the air temperature measured above the water's surface cooled down and then leveled off, showing that thermal energy was not the driving force behind the effect.

Other key indicators that showed up included the way the evaporation effect varied depending on the angle of the light, the exact color of the light, and its polarization. None of these varying characteristics should happen because at these wavelengths, water hardly absorbs light at all -- and yet the researchers observed them.

The effect is strongest when light hits the water surface at an angle of 45 degrees. It is also strongest with a certain type of polarization, called transverse magnetic polarization. And it peaks in green light -- which, oddly, is the color for which water is most transparent and thus interacts the least.

Chen and his co-researchers have proposed a physical mechanism that can explain the angle and polarization dependence of the effect, showing that the photons of light can impart a net force on water molecules at the water surface that is sufficient to knock them loose from the body of water. But they cannot yet account for the color dependence, which they say will require further study.

They have named this the photomolecular effect, by analogy with the photoelectric effect that was discovered by Heinrich Hertz in 1887 and finally explained by Albert Einstein in 1905. That effect was one of the first demonstrations that light also has particle characteristics, which had major implications in physics and led to a wide variety of applications, including LEDs. Just as the photoelectric effect liberates electrons from atoms in a material in response to being hit by a photon of light, the photomolecular effect shows that photons can liberate entire molecules from a liquid surface, the researchers say.

"The finding of evaporation caused by light instead of heat provides new disruptive knowledge of light-water interaction," says Xiulin Ruan, professor of mechanical engineering at Purdue University, who was not involved in the study. "It could help us gain new understanding of how sunlight interacts with cloud, fog, oceans, and other natural water bodies to affect weather and climate. It has significant potential practical applications such as high-performance water desalination driven by solar energy. This research is among the rare group of truly revolutionary discoveries which are not widely accepted by the community right away but take time, sometimes a long time, to be confirmed."

Solving a cloud conundrum

The finding may solve an 80-year-old mystery in climate science. Measurements of how clouds absorb sunlight have often shown that they are absorbing more sunlight than conventional physics dictates possible. The additional evaporation caused by this effect could account for the longstanding discrepancy, which has been a subject of dispute since such measurements are difficult to make.

"Those experiments are based on satellite data and flight data," Chen explains. "They fly an airplane on top of and below the clouds, and there are also data based on the ocean temperature and radiation balance. And they all conclude that there is more absorption by clouds than theory could calculate. However, due to the complexity of clouds and the difficulties of making such measurements, researchers have been debating whether such discrepancies are real or not. And what we discovered suggests that hey, there's another mechanism for cloud absorption, which was not accounted for, and this mechanism might explain the discrepancies."

Chen says he recently spoke about the phenomenon at an American Physical Society conference, and one physicist there who studies clouds and climate said they had never thought about this possibility, which could affect calculations of the complex effects of clouds on climate. The team conducted experiments using LEDs shining on an artificial cloud chamber, and they observed heating of the fog, which was not supposed to happen since water does not absorb in the visible spectrum. "Such heating can be explained based on the photomolecular effect more easily," he says.

Lv says that of the many lines of evidence, "the flat region in the air-side temperature distribution above hot water will be the easiest for people to reproduce." That temperature profile "is a signature" that demonstrates the effect clearly, he says.

Zhang adds: "It is quite hard to explain how this kind of flat temperature profile comes about without invoking some other mechanism" beyond the accepted theories of thermal evaporation. "It ties together what a whole lot of people are reporting in their solar desalination devices," which again show evaporation rates that cannot be explained by the thermal input.

The effect can be substantial. Under the optimum conditions of color, angle, and polarization, Lv says, "the evaporation rate is four times the thermal limit."

Already, since publication of the first paper, the team has been approached by companies that hope to harness the effect, Chen says, including for evaporating syrup and drying paper in a paper mill. The likeliest first applications will come in the areas of solar desalinization systems or other industrial drying processes, he says. "Drying consumes 20 percent of all industrial energy usage," he points out.

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World's oases threatened by desertification, even as humans expand them

Oases are important habitats and water sources for dryland regions, sustaining 10% of the world's population despite taking up about 1.5% of land area. But in many places, climate change and anthropogenic activities threaten oases' fragile existence. New research shows how the world's oases have grown and shrunk over the past 25 years as water availability patterns changed and desertification encroaches on these wet refuges.

"Although the scientific community has always emphasized the importance of oases, there has not been a clear map of the global distribution of oases," said Dongwei Gui, a geoscientist at the Chinese Academy of Science who led the study. "Oasis research has both theoretical and practical significance for achieving United Nations Sustainable Development Goals and promoting sustainable development in arid regions."

The study found that oases around the world grew by more than 220,149 square kilometers (85,000 square miles) from 1995 to 2020, mostly due to intentional oasis expansion projects in Asia. But desertification drove the loss of 134,300 square kilometers (51,854 square miles) of oasis over the same period, also mostly in Asia, leading to a net growth of 86,500 square kilometers (about 33,400 square miles) over the study period.

The findings highlight the risk climate change and anthropogenic stressors pose to these wet sanctuaries and can inform water resource management and sustainable development in arid regions. The study was published in the AGU journal Earth's Future, which publishes interdisciplinary research on the past, present and future of our planet and its inhabitants.

The birth and death of an oasis

Oases are important sources of water for humans, plants and animals in the world's drylands, supporting a majority of productivity and life in deserts. They form when groundwater flows and settles into low-lying areas, or when surface meltwater flows downslope from adjacent mountain ranges and pools. The existence of an oasis depends primarily on having a reliable source of water that is not rainfall. Today, oases are found in 37 countries; 77% of oases are located in Asia, and 13% are found in Australia.

Gui and his co-investigators wanted to understand the global distribution and dynamic changes of oases and see how they respond to a changing environment, such as variations in climate, water resources and human activities. Using data from the European Space Agency's Climate Change Initiative Land Cover Product, the team categorized the land surface into seven categories: forest, grassland, shrub, cropland, water, urban and desert.

The researchers used satellite data to look for green, vegetated areas within dryland areas, indicating an oasis, and tracked changes over 25 years. Changes in the greenness of vegetation indicated changes in land use and oasis health, the latter of which can be influenced by both human activity and climate change. They also looked at changes in land surface type to find conversions of land use.

The researchers found that global oasis area increased by 220,800 square kilometers (85,251 square miles) over the 25-year timeframe. Most of that increase was from humans intentionally converting desert land into oases using runoff water and groundwater pumping, creating grasslands and croplands. The increase was concentrated in China, where management efforts have contributed more than 60% of the growth, Gui said. For example, more than 95% of the population in China's Xinjiang Uygur Autonomous Region lives within an oasis, motivating conservation and a 16,700 square kilometer (6,448 square mile) expansion of the oasis, Gui said.

Countering human efforts to expand oases, desertification contributed to oasis loss. Worldwide, the researchers found there was a loss of more than 134,000 square kilometers (51,738 square miles) of oasis land over the past 25 years. The researchers estimate that changes to oases have directly affected about 34 million people around the world.

Overall, between gains and losses, oases had a net growth of 86,500 square kilometers (33,397 square miles) from 1995 to 2020 -- but most gains were from the artificial expansion of oases, which may not be sustainable in the future.

Long-term oasis sustainability

The study highlighted ways to sustain healthy oases, including suggestions for improving water resource management, promoting sustainable land use and management and encouraging water conservation and efficient use. These efforts are especially important as the climate continues to change, Gui said.

Humans' overexploitation of dwindling groundwater can limit oasis sustainability, as well as long-term glacier loss. While higher temperatures increase glacier melt, temporarily boosting oases' water supplies, "as glaciers gradually disappear, the yield of meltwater will eventually decrease, leading to the shrinkage of oases once again," Gui said.

International cooperation plays a crucial role in oasis sustainability, Gui said.

"Due to the unique mechanism of oasis formation, a river basin often nurtures multiple oases across several countries, making transboundary cooperation key to addressing water scarcity and promoting sustainable development," he said.

Read more at Science Daily

38 trillion dollars in damages each year: World economy already committed to income reduction of 19 % due to climate change

Even if CO2 emissions were to be drastically cut down starting today, the world economy is already committed to an income reduction of 19 % until 2050 due to climate change, a new study published in Nature finds. These damages are six times larger than the mitigation costs needed to limit global warming to two degrees. Based on empirical data from more than 1,600 regions worldwide over the past 40 years, scientists at the Potsdam Institute for Climate Impact Research (PIK) assessed future impacts of changing climatic conditions on economic growth and their persistence.

"Strong income reductions are projected for the majority of regions, including North America and Europe, with South Asia and Africa being most strongly affected. These are caused by the impact of climate change on various aspects that are relevant for economic growth such as agricultural yields, labour productivity or infrastructure," says PIK scientist and first author of the study Maximilian Kotz. Overall, global annual damages are estimated to be at 38 trillion dollars, with a likely range of 19-59 trillion dollars in 2050. These damages mainly result from rising temperatures but also from changes in rainfall and temperature variability. Accounting for other weather extremes such as storms or wildfires could further raise them.

Huge economic costs also for the United States and European Union

"Our analysis shows that climate change will cause massive economic damages within the next 25 years in almost all countries around the world, also in highly-developed ones such as Germany, France and the United States," says PIK scientist Leonie Wenz who led the study. "These near-term damages are a result of our past emissions. We will need more adaptation efforts if we want to avoid at least some of them. And we have to cut down our emissions drastically and immediately -- if not, economic losses will become even bigger in the second half of the century, amounting to up to 60% on global average by 2100. This clearly shows that protecting our climate is much cheaper than not doing so, and that is without even considering non-economic impacts such as loss of life or biodiversity."

To date, global projections of economic damages caused by climate change typically focus on national impacts from average annual temperatures over long-time horizons. By including the latest empirical findings from climate impacts on economic growth in more than 1,600 subnational regions worldwide over the past 40 years and by focusing on the next 26 years, the researchers were able to project sub-national damages from temperature and rainfall changes in great detail across time and space all the while reducing the large uncertainties associated with long-term projections. The scientists combined empirical models with state-of-the-art climate simulations (CMIP-6). Importantly, they also assessed how persistently climate impacts have affected the economy in the past and took this into account as well.

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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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Climate change threatens Antarctic meteorites

Using artificial intelligence, satellite observations, and climate model projections, a team of researchers from Switzerland and Belgium calculate that for every tenth of a degree of increase in global air temperature, an average of nearly 9,000 meteorites disappear from the surface of the ice sheet. This loss has major implications, as meteorites are unique samples of extraterrestrial bodies that provide insights into the origin of life on Earth and the formation of the Moon.

Disappearing at an alarming rate

By 2050, about a quarter of the estimated of 300,000 -- 800,000 meteorites in Antarctica will be lost due to glacial melt.

By end of the century, researchers anticipate that number could rise approaching a loss of meteorites closer to three-quarters of the meteorites on the continent under a high-warming scenario.

Published in the journal Nature Climate Change, Harry Zekollari co-led the study while working under Professor Daniel Farinotti in the Laboratory of Hydraulics, Hydrology and Glaciology at the Department of Civil, Environmental and Geomatic Engineering at ETH Zurich.

Zekollari and co-lead Veronica Tollenaar, Université Libre de Bruxelles, reveal in the study that ongoing warming results in the loss of about 5,000 meteorites a year, outpacing the collection efforts of Antarctic meteorites by a factor five.

Meteorites -- time capsules of the universe

Zekollari, now an Associate Professor of Glaciology at Vrije Universiteit Brussel, calls for a major international effort to preserve the scientific value of meteorites, "We need to accelerate and intensify efforts to recover Antarctic meteorites. The loss of Antarctic meteorites is much like the loss of data that scientists glean from ice cores collected from vanishing glaciers -- once they disappear, so do some of the secrets of the universe."

Meteorites are fragments from space that provide unique information about our solar system.

Antarctica is the most prolific place to find meteorites, and to date, about 60 percent of all meteorites ever found on Earth have been collected from the surface of the Antarctic ice sheet.

The flow of the ice sheet concentrates meteorites in so-called "meteorite stranding zones," where their dark crust allows them to be easily detected.

In addition to intensifying recovery operations, there is potential to increase the efficiency of meteorite recovery missions in the short term.

This potential relies mainly on data-driven analysis to identify unexplored meteorite stranding zones and mapping areas exposing blue ice where meteorites are often found.

Extraterrestrial heritage slipping away

Due to their dark colour, meteorites preferentially heat up with respect to the surrounding ice.

As this heat transfers from the meteorites to the ice, it can warm up the ice, and eventually cause the ice to locally melt, leading to a sinking of meteorites underneath the surface of the ice sheet.

Once the meteorites enter the ice sheet, even at shallow depths, they cannot be detected anymore, and they are thus lost for science.

As atmospheric temperatures increase, so does the surface temperature of the ice, intensifying the loss.

"Even when temperatures of the ice are well below zero, the dark meteorites warm-up so much in the sun that they can melt the ice directly beneath the meteorite. Through this process, the warm meteorite creates a local depression in the ice and over time fully disappears under the surface," says Tollenaar.

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