Tropical rivers emit less greenhouse gases than previously thought

Lowland tropical rivers emit large quantities of greenhouse gases, with rates influenced by seasonal flooding.
Photo Credit: Jenny Davis

Tropical inland waters don’t produce as many greenhouse gas emissions as previously estimated, according to the results of an international study, led by Charles Darwin University and involving researchers from Umeå University.

The study, published in Nature Water, aimed to better understand greenhouse gas emissions in tropical rivers, lakes and reservoirs by collating the growing amount of observations from across the world’s tropics – including many systems that were previously less represented in global datasets.

Researchers from Umeå University played a key role in the work, estimating the surface area of rivers and contributing to the data analysis that underpins the study’s findings.

How Hard Is It to Dim the Sun

An illustration of climate geoengineering techniques, including stratospheric aerosol injection (SAI), cirrus cloud thinning (CCT), and marine cloud brightening (MCB), and their proposed delivery systems and potential impacts. Natural stratospheric aerosol release from a volcanic eruption is also shown for context. Surface albedo geoengineering (SAG), which is based on increasing the albedo of various surfaces, is also represented with two examples: installing white roofs on urban buildings and modifying plants and shrubs surface.
Image Credit: Licensed under Creative Commons.

Once considered a fringe idea, the prospect of offsetting global warming by releasing massive quantities of sunlight-reflecting particles into Earth’s atmosphere is now a matter of serious scientific consideration. Hundreds of studies have modeled how this form of solar geoengineering, known as stratospheric aerosol injection (SAI), might work. There is a real possibility that nations or even individuals seeking a stopgap solution to climate change may try SAI—but the proponents dramatically underestimate just how difficult and complicated it will be, say researchers from Columbia University.

“Even when simulations of SAI in climate models are sophisticated, they’re necessarily going to be idealized. Researchers model the perfect particles that are the perfect size. And in the simulation, they put exactly how much of them they want, where they want them. But when you start to consider where we actually are, compared to that idealized situation, it reveals a lot of the uncertainty in those predictions,” says V. Faye McNeill, an atmospheric chemist and aerosol scientist at Columbia’s Climate School and Columbia Engineering.

Retired croplands offer hope for carbon storage

An experiment at Cedar Creek Ecosystem Science Reserve tested the long-term ability of abandoned farmland to store carbon.
Photo Credit: Maowei Liang, College of Biological Sciences

Burning fossil fuels has elevated atmospheric carbon dioxide, causing massive changes in the global climate including extreme temperatures and weather events here in the Midwest. Meanwhile, human activities have increased the amount of nutrients like nitrogen and phosphorus in grasslands and forests. These are the elements in fertilizer that make lawns greener and farmlands more productive.

This overabundance of nutrients can lead to reduced water quality, the spread of invasive species and the loss of native species. However, it can also help plants capture carbon dioxide from the atmosphere and store it in the soil. This creates a paradox for environmental management: will reducing nutrient pollution make climate change worse by causing a release of carbon dioxide from the soil?

What Is: Extinction Level Events

A Chronicle of Earth's Biotic Crises and an Assessment of Future Threats
Image Credit: Scientific Frontline

Defining Biotic Catastrophe

The history of life on Earth is a story of breathtaking diversification and innovation, but it is punctuated by chapters of profound crisis. These are the extinction level events—catastrophes of such magnitude that they fundamentally reset the planet's biological clock. Popular imagination often pictures a single, sudden event, like the asteroid that sealed the fate of the dinosaurs. The geological reality, however, is more complex and, in many ways, more instructive for our current era. Understanding these events requires a rigorous scientific framework that moves beyond simple notions of species loss to appreciate the systemic collapse of entire global ecosystems.

A New Study Indicates Forest Regeneration Provides Climate Benefits, but Won’t Offset Fossil Fuels

Forest regrowth after 5 years since agricultural abandonment near Pucallpa, Ucayali, Peru.
Photo Credit: Jorge Vela Alvarado, Universidad Nacional de Ucayali

When farmland is abandoned and allowed to return to nature, forests and grasslands naturally regrow and absorb carbon dioxide from the atmosphere—helping fight climate change. However, a new study in the journal Global Biogeochemical Cycles, led by scientists at Columbia University, reveals an important wrinkle in this story: these regenerating ecosystems also release other greenhouse gases that reduce some of their climate benefits. The good news? Even accounting for these other gases, letting land regenerate naturally still provides important climate benefits compared with keeping it in agriculture.

Lead author Savannah S. Cooley, a research scientist at NASA Ames Research Center and a recent PhD graduate of Columbia’s Ecology, Evolution and Environmental Biology program, and her team of co-authors analyzed data from 115 studies worldwide to understand how forests and grasslands affect the climate through three key greenhouse gases: carbon dioxide, methane and nitrous oxide. While previous research focused mainly on carbon dioxide absorption by growing trees, this study examined a more complete picture.

Hotter does mean wetter

How rising temperatures will affect rainfall in Japan.
Illustration Credit: KyotoU / Takemi lab

Around the world, we are already witnessing the detrimental effects of climate change, which we know will only become more severe. Extreme weather events such as heavy rainfall, tropical cyclones, and heat waves are projected to intensify, and this will negatively impact both human society and natural ecosystems.

Assessing how climate change affects extreme weather is important not only from a scientific point of view, but also from a practical perspective. It is critical that we start adapting to climate change and mitigating the effects of potential disasters.

This situation has motivated a team of researchers at Kyoto University to investigate how climate change -- in particular, rising temperatures -- affects precipitation in Japan. The team has focused on heavy rainfall patterns and what kind of atmospheric conditions influence their characteristics.

Helping farmers, boosting biofuels

Doug Collins and Teal Potter, co-authors on the new paper, stand in a field of triticale. The cover crop was grown to study its viability as a biofuel source.
Photo Credit: Chad Kruger/WSU

New research has found cover crops that are viable in Washington’s normal “off season” don’t hurt the soil and can be sold as a biofuel source.

After harvest, farmland often sits fallow and unused until growers seed in the next crop. Soil can erode, weeds can take root, and farmers don’t make any money during that time. Cover crops can eliminate or reduce some of those issues, but many farmers have concerns about their effects on soil quality, a reduced growing window for their primary crop, and the inability to sell the cover crop.

In a paper recently published in the journal Biomass and Bioenergy, a team led by Washington State University scientists looked at four cover crops grown for multiple years in western and central Washington fields. Two showed promising results.

Locking carbon in trees and soils could ‘stabilize climate for centuries’ – but only if combined with underground storage

Photo Credit: Veronica Lorine

Research on a ‘portfolio approach’ to carbon removal enables firms to mix expensive tech-based solutions that inject carbon deep underground with lower-cost and currently more available nature-based options, such as forests and biochar. 

A team of researchers, led by Cambridge University, has now formulated a method to assess whether carbon removal portfolios can help limit global warming over centuries.

The approach also distinguishes between buying credits to offset risk versus claiming net-negative emissions.

The study paves the way for nature-based carbon removal projects – such as planting new forests or restoring existing ones – to become effective climate change solutions when balanced with a portfolio of other removal techniques, according to researchers.

They say the findings, published in the journal Joule, show how nature-based and technology-based carbon storage solutions can work together through the transition to net zero, challenging the notion that only permanent tech-based “geological storage” can effectively tackle climate change.

Each fossil fuel project linked to additional global warming

Photo Credit: Roman Khripkov

Individual fossil fuel projects can no longer be considered too small to matter according to new Australian research linking each new investment in coal and gas extraction with measurable increases in global temperatures.

Published in the Nature journal Climate Action, climate scientists from six Australian universities, including the University of Melbourne, have revealed findings that debunk claims individual fossil fuel projects have little impact on global warming.

The research led by the ARC Centre of Excellence for the Weather of the 21st Century focused on the Scarborough gas project in Northwest Australia. It found that the project alone is estimated to lead to an increase of approximately 0.00039°C in global temperature from 876 million tons of CO2 emissions.

University of Melbourne Associate Professor Andrew King from the School of Geography, Earth and Atmospheric Sciences explained that while 0.00039°C of additional warming may seem relatively small, its impacts on society and the environment are actually large.

“This degree of warming could expose over half a million people to unprecedented extreme heat,” Associate Professor King said.

Study links wind-blown dust from receding Salton Sea to reduced lung function in area children

Researchers with the UC Irvine-led study sample dust at the southern edge of the Salton Sea. Joe C. Wen School of Population & Public Health
Photo Credit: Courtesy of University of California, Irvine

Children living near the Salton Sea, in Southern California’s desert region of Imperial County, are experiencing poorer lung function than children exposed to less wind-blown dust, according to a new study led by researchers at the University of California, Irvine’s Joe C. Wen School of Population & Public Health.

They found that higher dust exposure – measured in hours per year – was linked to lower lung function, with the negative effects most pronounced among children living closest to the lake. The work, published in the American Journal of Respiratory and Critical Care Medicine, marks one of the first investigations to directly link dust events from a drying saline lake to measurable declines in children’s respiratory health.

A federal grant from the National Institute of Environmental Health Sciences and the Southern California Environmental Health Sciences Center funded the research in partnership with the Imperial Valley community-based organization Comite Civico del Valle.

“Cocktails” of common pharmaceuticals in our waterways may promote antibiotic resistance

Photo Credit: Nana K.

New research has shown, for the first time, how mixtures of commonly used medications which end up in our waterways and natural environments might increase the development of antibiotic-resistant bacteria.

When humans or animals take medications, as much as 90 percent can pass through the body and into natural environments, via waste-water, or run-off from fields, ending up in the ocean. 

In the environment, this build-up of antibiotic medicines can accumulate to a strength sufficient to kill the bacteria that live there; this can result in bacteria evolving defenses that help them to survive these concentrations, which can mean they are also resistant to antibiotics used to treat them if they later infect humans. However, less is known about how build-up of other medicines also affects bacteria, and until now, scientists have largely investigated the effect of these medications on triggering this antibiotic resistance one-at-a-time. 

What Is: El Niño, La Niña, and a Climate in Flux

Image Credit: Scientific Frontline / NOAA

The Planet's Most Powerful Climate Cycle

In 1997, a climatic event of unprecedented scale began to unfold in the tropical Pacific Ocean. Dubbed the "El Niño of the century," it triggered a cascade of extreme weather that reshaped global patterns for over a year. It unleashed devastating floods and droughts, sparked massive forest fires, decimated marine ecosystems, and crippled national economies. By the time it subsided in 1998, the event was estimated to have caused more than 22,000 deaths and inflicted over $36 billion in damages worldwide. Nearly two decades later, the powerful 2015-16 El Niño, supercharged by a background of long-term global warming, helped propel 2016 to become the hottest year on record and directly impacted the lives and livelihoods of over 60 million people.

These catastrophic events are not random acts of nature but manifestations of the planet's most powerful and influential climate cycle: the El Niño-Southern Oscillation (ENSO). This naturally occurring phenomenon is a periodic, irregular fluctuation of sea surface temperatures and atmospheric pressure across the vast expanse of the equatorial Pacific Ocean. At its heart are two opposing phases: El Niño ("The Little Boy" in Spanish), a significant warming of the ocean surface, and La Niña ("The Little Girl"), a countervailing cooling. Together with a neutral "in-between" state, they form a planetary-scale pendulum that swings irregularly every two to seven years, dictating patterns of drought and flood, storm and calm, across the globe.

Climate change may increase the spread of neurotoxin in the oceans

The researchers’ findings raise concerns about how climate change may affect the levels of methylmercury in fish and shellfish.
Photo Credit: Johnér Bildbyrå AB

Climate-driven oxygen loss in the Black Sea thousands of years ago triggered the expansion of microorganisms capable of producing the potent neurotoxin methylmercury. That is shown in a new study published in Nature Water, led by Eric Capo at Umeå University, which suggests that similar processes could occur in today’s warming oceans.

Methylmercury is a highly toxic compound that accumulates in fish and seafood, posing severe health risks to humans. It is formed when certain microbes convert inorganic mercury under low-oxygen conditions.

Today, climate change is causing such oxygen-depleted areas to expand in coastal marine environments, including parts of the Baltic Sea. Warmer and more stagnant waters mix less efficiently, and increased algal blooms contribute to oxygen loss in deeper layers, creating ideal conditions for these microbes.

Air Pollution Can Contribute to Obesity and Diabetes

The most significant sources of fine air pollutants include exhaust fumes from cars, industrial plants and heating systems, as well as emissions from construction sites and forest fires.
Photo Credit: Uvi D

Long-term exposure to fine air pollution can impair metabolic health by disrupting the normal function of brown fat in mice. A study co-led by the University of Zurich shows that this occurs through complex changes in gene regulation driven by epigenetic mechanisms. The results demonstrate how environmental pollutants contribute to the development of insulin resistance and metabolic diseases.

There is growing evidence that air pollution is not just harmful to our lungs and heart, but also plays a significant role in the development of metabolic disorders like insulin resistance and type 2 diabetes. A new study co-led by Francesco Paneni, professor at the Center for Translational and Experimental Cardiology of the University of Zurich (UZH) and the University Hospital Zurich (USZ), and Sanjay Rajagopalan, professor at the Case Western Reserve University, Cleveland, now sheds light on the topic.

Green Energy and Innovation Can Increase Greenhouse Gas Emissions

The introduction of renewable energy sources in developing Asian countries may lead to a short-term increase in greenhouse gas emissions.
Photo Credit: Nicholas Doherty

Scientists at Ural Federal University have found that the introduction of renewable energy sources (RES) and technological innovations in developing Asian countries can lead to a short-term increase in greenhouse gas emissions. The reason is the effect of rebound and insufficient effectiveness of regulatory systems. This calls into question the effectiveness of current measures to achieve the goals of the Paris Agreement, the researchers believe. They wrote on this topic in an article in the journal Energy Economics.

"In Asia, more efficient coal-fired power plants or cheaper solar energy can lower electricity prices, leading to increased energy consumption by industry and households in general. Although innovations reduce CO₂ emissions in the short term, they actually increase emissions in the medium and long term, as efficiency gains drive growth in industrial activity and energy demand. This is a classic rebound effect: efficiency stimulates economies of scale, negating the initial environmental benefits," explained Kazi Sohag, co-author of the paper and head of the UrFU Laboratory of Economic Policy and Natural Resources.

SwRI produces, evaluates sustainable aviation fuel made from e-fuel

A multidisciplinary team at Southwest Research Institute (SwRI) produced, characterized and tested standard jet fuel along with two sustainable aviation fuels (SAF), including one developed at SwRI, through an internally funded project. A custom jet engine test stand was used to gather emissions and particulate data.
Photo Credit: Southwest Research Institute

Southwest Research Institute produced a batch of blended sustainable aviation fuel (SAF) through a refinery process that started with electrofuels or e-fuels made from carbon dioxide and green hydrogen. Using internal research funding, a multidisciplinary team produced and characterized the SAF, along with two other commercially available fuels, before collecting emissions and particulate data to support the aviation industry’s emissions goals.

“Aviation is difficult to decarbonize due to the fuel density and power required for flight,” said Francesco Di Sabatino, a group leader in SwRI’s Mechanical Engineering Division. “With this project we’re gathering important data for conventional fuel and two different SAFs.”

Conventional jet fuel is made from petroleum that burns inside a jet engine. Fueling jets with SAF could help reduce carbon emissions. Worldwide air travel accounts for 2% of all carbon emissions, and 12% of all carbon emissions from transportation. The team tackled three focus areas — production, characterization and testing.

Heatwaves at Sea May Force the Ocean to Release More CO2

Marine heatwaves are disrupting the ocean’s ability to store carbon
Image Credit: Scientific Frontline / AI generated

Heatwaves not only occur on land – they also occur in the oceans, causing ocean temperatures to stay warmer than normal for longer periods. Marine heatwaves can cover huge areas of the sea and have major effects on marine life, from plankton to reefs and whales.

Now, a new study shows that marine heatwaves may also affect how carbon is stored in the ocean.

The ocean is one of Earths biggest carbon sinks. It soaks up vast amounts of CO2 from the atmosphere, and in the surface water, algae and other photosynthetic microorganisms capture it and convert it to organic carbon. When these organisms die and sink to the bottom, the carbon sinks with them. In the deep ocean, the removed carbon can be locked away for hundreds, even thousands of years.

Engineers Develop Solid Lubricant to Replace Toxic Materials in Farming

Photo Credit: Courtesy of North Carolina State University

Researchers have developed a new class of nontoxic, biodegradable solid lubricants that can be used to facilitate seed dispersal using modern farming equipment, with the goal of replacing existing lubricants that pose human and environmental toxicity concerns. The researchers have also developed an analytical model that can be used to evaluate candidate materials for future lubricant technologies.

Modern farming makes use of various machines to accurately and efficiently plant seeds in the ground. However, it can be difficult to prevent the seeds from jamming in these machines. To keep the seeds flowing smoothly, farmers use solid lubricants that prevent the seeds from clumping up or sticking together. Unfortunately, commercially available lubricants make use of talc or microplastics, and can pose threats to farmers, farmland and pollinators.

“Lubricants are essential to modern farming, but existing approaches are contributing to toxicity in our farmlands that affect farmer health, soil health and pollinators that are essential to our food supply,” says Dhanush Udayashankara Jamadgni, co-lead author of a paper on the work and a Ph.D. student at North Carolina State University. “We’ve developed a new class of safe solid lubricants that are effective and nontoxic.”

Lake Tahoe Algae Experiment Suggests Seasonal Shifts Ahead

UC Davis researchers conduct periphyton research at Lake Tahoe.
Photo Credit: Brandon Berry, UC Davis Tahoe Environmental Research Center

As the climate warms and nutrient inputs shift, algal communities in cool, clear mountain lakes like Lake Tahoe will likely experience seasonal changes, according to a study from the University of California, Davis. 

Periphyton, that fuzzy layer of attached algae covering the rocks as you step into the water, is a healthy and critical part of a lake’s food web. Periphyton blooms, however, signal changes that can degrade both water quality and a shoreline’s natural beauty.

Climate change is projected to increase global water temperatures by 1.8 to 7 degrees Fahrenheit by 2100. It’s also expected to increase nutrients to lake waters through increased runoff from higher intensity storms and more precipitation falling as rain rather than snow.

“A majority of lakes globally are warming as a result of climate change,” said lead author Nick Framsted, a master’s student in the UC Davis Environmental Science and Policy department and Tahoe Environmental Research Center when the study was conducted. “With their clear, cold waters, mountain lakes are exceptionally sensitive to changes in temperature and nutrients.”

Clam shells sound warning of Atlantic ‘tipping point’

Ocean quahog shells.
Photo Credit Paul Butler

A study of clam shells suggests Atlantic Ocean currents may be approaching a “tipping point”.

Scientists studied records of quahog clams (which can live for over 500 years) and dog cockles – because shell layers provide an annual record of ocean conditions.

They studied these natural archives to understand long-term patterns in Atlantic Ocean currents such as the Atlantic Meridional Overturning Circulation (AMOC) and the subpolar gyre (SPG).

Recent studies have debated possible AMOC and SPG tipping points – transitions that would transform climate patterns. For example, AMOC collapse would have far-reaching global effects, from harsher winters in north-west Europe to shifts in global rainfall patterns, while a weakening of the SPG would be less catastrophic but still bring substantial impacts, including more frequent extreme weather in the North Atlantic region.