It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
NEW YORK -- Railway exports of liquefied petroleum gases from the Canadian production hub of Edmonton, Alberta, to refining and trading centres in the United States are unusually high this summer due to strong demand from motor fuel blenders, according to storage broker The Tank Tiger.
The out-of-season surge in LPG flows highlights the knock-on effects of the Iran war on energy supply chains around the world, and how some government initiatives to shield consumers from the resulting price shocks have flipped long-standing trading dynamics.
LPG demand in the U.S. typically declines in summer as propane is no longer used for space heating, and as tighter restrictions on gasoline quality - designed to reduce smog-linked emissions - reduce the amount of butane added to motor fuel.
The U.S. government this year eased blending restrictions after its war against Iran sent prices surging at the pumps, allowing fuelmakers to continue adding high amounts of butane into gasoline.
The waivers have helped keep rail exports of LPG from Edmonton to the United States above 2025 and 2024 levels, said Steven Barsamian, chief operating officer at The Tank Tiger
Some 5.2 million barrels of LPG were exported by rail from Edmonton in May, up from about 3.6 million barrels in the same period last year, according to data compiled by The Tank Tiger and rail analytics firm RailState.
Weekly exports peaked in the first week of June at about 1.4 million barrels, about 400,000 barrels higher than last year’s peak during that time, the data showed.
While the data does not show the specific product loaded onto LPG railcars, market participants say the bulk of the arrivals are butane due to higher blending demand this year, Barsamian said. Most of the imports likely headed to Mont Belvieu, Texas, the key U.S. LPG storage hub and pricing benchmark for the Americas, he added.
The U.S. is the world’s largest butane exporter but has imported growing amounts of the blending component from Canada in recent years, mainly for refiners in the Midwest, Northeast and West Coast markets.
Total U.S. butane imports averaged 51,000 barrels per day last year, all of which was supplied by Canada, according to U.S. Energy Information Administration data.
The waivers of summertime fuel specifications have likely generated around 50,000 to 100,000 bpd of additional butane demand in the U.S., said Alex Hodes, director of energy market strategy at brokerage StoneX.
“Blending dynamics have been turned on their head,” Hodes said.
The price spread for butane between Edmonton and Mont Belvieu is near a historical high, with prices at the Texas hub at around US$1 per gallon, a premium of about 30 cents to Edmonton, making it attractive for traders to sell higher volumes to the U.S., Hodes added.
(Reporting by Shariq Khan in New York and Amanda Stephenson in Calgary; Editing by Liz Hampton and Nia Williams)
Friday, June 05, 2026
Wildfire emissions have reversed more than a decade of steady reductions in ozone
Summary author: Abigail Eisenstadt
American Association for the Advancement of Science (AAAS)
After more than a decade of steady decreases, surface ozone (O3) trends in North America reversed in 2015 despite policy mitigation efforts, report Weizhi Deng and colleagues. Their research links this reversal to O3 emissions from wildfires and additionally documents a related rise in premature mortality. “Despite regulated reductions in anthropogenic emissions of O3 precursors, observation stations indicate that policy-relevant surface O3 levels have plateaued,” the authors write, tying this phenomenon to an increase in wildfire emissions. They describe the relationship between wildfires and surface O3 trends more closely by using deep learning models to evaluate existing yet sparse EPA, satellite, and meteorological measurements, generating a dataset of daily surface O3 measurements at a 1-kilometer resolution in North America from 2003 to 2024. Doing so revealed that O3 trends flipped from a decrease of 0.65 parts per billion (ppb) per year before 2015 to an increase of 0.13 ppb per year after 2015. Further analyses determined this post-2015 rate would have stayed in decline (−0.25 ppb per year) if not for wildfire emissions. The authors then examined correlations between O3 trends and premature deaths, attributing emissions to an additional 318 deaths per year since 2013. Essentially, after 2013, the mortality rate attributable to wildfire-sourced O3 rose by 46%. Finally, Deng et al. examined O3 emissions from 2022 to 2024, a period marked by extreme fires and smoke in Canada. Results showed wildfire emissions alone exposed 43 million people to unhealthy levels of air pollution, in excess of the United States’ O3 air quality standard of 70 ppb. The authors suggest that these emissions prevented the United States from tightening its O3 air quality standard by 4 ppb. They elaborate: “If the O3 standard were lowered to 65 ppb, 60% of the population (202 million people) would fall into nonattainment, and under a 60-ppb standard, the fraction would increase to 87% (294 million people). These findings demonstrate the challenge in adopting a more stringent O3 standard as growing wildfires contribute to high O3 episodes.”
A new University of Iowa-led study has determined that wildfires since 2015 have led to rises in surface ozone pollution across much of the continental United States, creating unhealthy air and contributing to hundreds additional premature deaths annually. The researchers warn surface ozone pollution could continue to worsen as wildfires become more prevalent.
Ozone pollution has worsened in much of the continental United States over the past decade, fueled by wildfires and the long-distance transport of unhealthy air, according to a new study led by University of Iowa researchers and published in the journal Science.
Exposure to surface ozone pollution stemming from wildfires has contributed to more than 300 additional premature deaths each year in the U.S. since 2013, the researchers conclude, with significant spikes in premature deaths in 2020, 2021, and 2023.
Study authors calculated the concentration of surface ozone, also known as smog, on a kilometer-by-kilometer (0.6 miles) grid for the continental U.S between 2003 and 2024. The researchers report that air quality due to ozone pollutants worsened from 2015 to 2024 across much of the Midwest and large swaths of the Western U.S.
The researchers also found that the increase in wildfire-driven ozone pollution over the past decade has undercut air-quality improvements achieved before 2015, largely through reductions in automobile emissions, which are a main contributor to surface ozone.
The study comes as wildfire activity in the U.S. has reached historic levels this spring, with blazes charring millions of acres from California to Georgia.
Surface ozone is caused by a chemical reaction involving carbon monoxide, an odorless, colorless gas emitted when wildfires don’t fully combust organic matter, such as trees. Surface ozone can form near fires when nitrogen oxide combines with carbon monoxide and sunlight.
But smog also can form far away from wildfires when carbon monoxide rises into Earth’s upper atmosphere and travels long distances before falling to the surface and undergoing chemical reactions involving sunlight and sources such as tailpipe emissions.
“The bottom line is the air is getting worse in these regions, and the reason is pollutants are being transported long distances from wildfires in the western U.S. and Canada,” says Jun Wang, Lichtenberg Family Chair in the Department of Chemical and Biochemical Engineering and the study’s corresponding author. “We show in high spatial resolution how a large part of the continental U.S. has been affected by worsened air quality through surface ozone pollution.”
Surface ozone levels in the U.S. have increased by 0.13 parts per billion (ppb) annually between 2015 and 2024, the researchers calculated. That reverses annual decreases in surface ozone levels since 2003, due in part to tightened federal regulations around tailpipe emissions. The study authors report that surface ozone levels would have continued to decrease during the study period “if fire impacts were removed, suggesting that fires are the major driver of the national trend reversal.”
"While U.S. air quality regulations have reduced surface ozone, a pollutant linked to respiratory and cardiovascular diseases, this progress has reversed since around 2015,” says Weizhi Deng, a graduate research assistant in Wang’s group who led the modeling linking wildfires and surface ozone pollution and is the study’s first author. “Wildfire smoke has become a major driver of increasing ozone pollution, especially in the western and midwestern United States."
The Canadian wildfires in 2023 were especially noteworthy for their effects on surface ozone pollution. During that fire season alone, surface ozone levels exceeded federal air quality standards for 148 million Americans — 44% of the continental U.S. population, the authors write. In the Midwest, surface ozone exceeded safe levels for more than one week, and the pollution extended as far as New York, Texas, and Georgia.
The pollutants had discernible effects on human health: The researchers calculated 7,974 smog-induced premature deaths in the U.S. in 2023.
“These results underscore the escalating public health burden of wildfire-driven ozone pollution,” the study authors write.
While the Environmental Protection Agency sets the national standard for surface ozone, it falls largely to states and cities to address unhealthy air in their communities. The problem with that, Wang notes, is those entities have little control over foul air that originates from wildfires far away.
“When air quality is poor — even when the pollution is from elsewhere — the responsibility is on the local or state authority to collect the evidence and then file an ‘exceptional event claim’ to the EPA,” says Wang, who is associate director of the Iowa Technology Institute. “That could be fine, but those exceptional events are not becoming exceptional anymore.”
The researchers derived surface ozone concentrations and premature deaths estimates from satellite data and approximately 1,000 ground-based stations that monitor air quality. The data from surface stations can be extensive, but it does not provide complete spatial coverage and can be lacking in rural areas. So, the researchers employed “deep learning,” which enables computer systems to cluster data and produce accurate predictions, to calculate the surface ozone concentrations. They calculated premature deaths through a formula that incorporated average lifespan, ozone exposure, and population density.
The results in part mirror a 2023 study, led by Wang and published in the journal The Lancet Planetary Health, that tabulated wildfires’ effect on air quality and human health in the continental U.S. through the rise in black carbon, a fine-particle air pollutant that has been linked to respiratory and heart disease.
“While there are regional differences, in general the impact of surface ozone is always bigger than black carbon,” Wang says.
The study, “Fires reverse progress toward ozone air quality standards in the USA,” was published online June 4.
The Port of Long Beach wants to have methanol bunkering available to support the next generation of dual-fuel ships, and it has selected a novel way of going about it. The port's commission has signed off on an incentive award - a prize - that will be awarded to the first ship to carry out a full-scale methanol bunkering evolution at Long Beach.
The port's "Clean Fuel Bunkering Challenge Incentive Award" is a $1 million prize, payable to a vessel operator rather than a fuel supplier. Details on eligibility will be forthcoming, the port said.
There are about 400 dual-fuel methanol ships in operation today, but most still run on bunker fuel, since practical supplies of green methanol are scarce. Gray methanol - derived from natural gas - has a higher carbon footprint than HFO due to the energy-intensive process of manufacturing it, and is not viewed as a long-term climate-friendly solution; carbon capture during the production process can reduce this concern, resulting in low-emissions blue methanol.
"We know the shipping industry is considering moving toward adopting methanol marine fuel for some great reasons – they want to reduce greenhouse gas emissions and improve air quality. Today, we’re giving them 1 million more reasons to embrace clean fuels," said Port of Long Beach CEO Dr. Noel Hacegaba. "We’re also seeing how rising fuel costs are strengthening the case for energy diversification and greater energy independence."
Beyond climate benefits, methanol is advantageous for its clean-burning emissions profile. It releases 95 percent less particulate matter, 99 percent less sulfur oxides and 60 percent fewer nitrogen oxides - a major improvement for those who live in smog-affected areas near the port. (This has been studied at Long Beach before: a Maersk-led project examined methanol as a fuel for cargo-handling equipment back at least as far as 1992.)
"Frontline communities in Los Angeles and Long Beach suffer from some of the worst pollution in the nation," said Cristhian Tapia-Delgado, Climate Campaigner for Southern California, Pacific Environment. "We applaud the Port of Long Beach for approving $1 million to move ocean shipping lines to clean bunkering, but we urge the Port to do everything possible to ensure the cleanest, safest and most sustainable alternative fuels are the ones that achieve long-term success at the Port."
In 2024, the dual fuel methanol boxship Alette Maersk called at neighboring Port of Los Angeles; she made the Pacific crossing on a combination of green methanol and biofuels, but it is understood that she did not take on green fuels during her visit to San Pedro Bay.
Tuesday, May 26, 2026
Residents of Polluted Areas Say Trump’s Regulatory Rollbacks Are “Getting Really Scary”
Many communities are also frustrated with state-level inaction but still see some opportunities for pushback.
President Donald Trump talks with Ford River Rouge Plant Manager Corey Williams (second from left), and Executive chair of Ford Motor Company Bill Ford Jr. (right) as they tour the Ford River Rouge Complex, on January 13, 2026 in Dearborn, Michigan.
Anna Moneymaker / Getty Images
Rita Robles’s life is ruled by allergies, the worst effects from which can last for months at a time. She uses rescue inhalers, a nebulizer, and a maintenance inhaler — on top of a slew of other medications. Even then, it’s often not enough.
“There are times when I’m outside just walking to the driveway and it’ll feel like something catches in my throat, and it causes me to go into a choking fit,” Robles told Truthout. “It’s miserable.”
Robles lives in a Houston, Texas, neighborhood suffocated by heavy industry — Denver Harbor, the largest petrochemical hub of the U.S. Robles, 56, calls the neighborhood a “disaster.”
She’s just one of millions of Americans, however, living in communities where people’s quality of life is secondary to the hum of big business — communities at the front line of the government’s regulatory rollbacks and budget cuts.
Since Donald Trump came back into office in January 2025, the federal government has either succeeded in, or is attempting to, weaken and roll back many of the country’s key environmental regulations and other broader programs. Things could get worse if the proposed Environmental Protection Agency (EPA) budget is approved, with its 52 percent cut in funding under the latest agency head, former New York Rep. Lee Zeldin.
Truthout spoke with three residents and community organizers living in Houston, Detroit, and California’s Central Valley. They shared their fears of the long-term ramifications from the federal government’s business-friendly purge of environmental protections, their frustration with state-level inaction, and what they see as openings for community pushback that can, with patience, lead to actionable change.
For people like Robles, the fight against regional polluters is done with one eye on the future.
In the vicinity of her home are concrete batch plants, gas stations, and truck-lined major thoroughfares, while in the near distance are the city’s towering petrochemical plants, phenomenal regional polluters. In 2019, the state classified Denver Harbor a cancer cluster due to the high occurrence of cancer cases in the area. A primary culprit is an old Southern Pacific Railroad site where creosote, a toxic wood preservative, was used liberally for decades. A lot of it leaked into the groundwater, causing a huge toxic plume.
While Denver Harbor’s residents have been let down by state and federal regulators, the current administration’s war on the regulatory state has Robles fearing that life there will be made even harder for younger generations.
“The way things are going, it’s getting really scary,” Robles said. Thinking of her two grandchildren — one 11 months old, the other 5 years old — she said she’s particularly worried about the administration’s attack on climate regulations, exemplified by Trump’s recent revocation of the 2009 endangerment finding.
The landmark Obama-era finding underpins virtually all the climate regulations under the Clean Air Act. Its reversal eliminates greenhouse gas emissions standards for cars and trucks. It could also lead to the rollback of climate-related rules governing other sources like power plants and oil and gas facilities, experts have warned.
“There is no way to reconcile EPA’s decision with the law, the science, and the reality of disasters that are hitting us harder every year,” wrote Earthjustice president Abigail Dillen in a statement immediately after the endangerment finding was revoked. “This is a slap in the face for all of the millions of Americans who are experiencing the devastating costs of extreme heat, wildfires, flooding, and storms.”
“A lot of these companies, they’re repeat offenders. But it’s cheaper for them to pay the fines then to make any changes to their business,” said Robles. “This Earth is a gift and we should take care of it. Instead, we’re destroying the climate.” Kettleman City, California
Marking the one-year anniversary of Trump’s second term, several reports illustrated how enforcement actions against the worst of the nation’s polluters have dropped off.
Civil lawsuits against polluters fell to a historic low in the first year of Trump’s second term with the DOJ filing only 16 complaints within that 12-month period, according to the Environmental Integrity Project.
In another report from earlier this year, Public Employees for Environmental Responsibility similarly found that the DOJ has slammed the breaks on enforcing Clean Air Act violations among the oil, gas, petrochemical, coal, and motor vehicle sectors. They found that the DOJ had lodged only one consent decree since Trump’s inauguration, compared to 26 in the first year of Trump’s first term, and 22 after Joe Biden’s first year in office.
Key bulwarks against the erosion of federal environmental protections are individual state governments. Most notably, California Gov. Gavin Newsom has positioned himself on the global stage as an antidote to the Trump administration by touting his environmental bona fides. This includes his record in helping to transition the state’s energy grid away from fossil fuels to renewables.
But in many of California’s toxic communities, residents voice deep frustration over a raft of state regulatory actions and bills they see as being overly permissive of industry’s wants, and too unprotective of disadvantaged communities in a way that mirrors the federal government’s current trajectory.
“The state has abandoned us,” said Veronica Aguirre, 55, who lives in Avenal, in the Central Valley. The small city — known for being halfway between the Bay and Los Angeles — is less than 10 miles from the Kettleman Hills Hazardous Waste Facility, which sits in the shadow of Kettleman City proper, where Aguirre’s aunt, cousin and other family members live.
Kettleman City is in one of the most pollution-burdened regions in the entire state, thanks to a confluence of air pollution, groundwater and drinking water threats, and its proximity to hazardous wastes. The nearby Kettleman Hills Hazardous Waste Landfill — one of two such designated landfills in the state — is a contributing factor to the area’s environmental woes thanks to a long, troubled history of enforcement violations (though the landfill management downplays their impact on Kettleman City). State regulators have allowed the landfill to continue operating on a permit that expired in 2013 while a new permit is being negotiated.
According to Aguirre, her family in Kettleman City all suffer serious health issues. Her cousin, she said, lost a kidney from a rare form of cancer. Babies are statistically more likely to be born there with serious congenital disabilities. “It’s a bitter pill to swallow,” said Aguirre of knowing about the risks to her family. Aguirre is a community organizer for the nonprofit organization Greenaction for Health and Environmental Justice, which advocates for frontline communities at contaminated sites up and down the state,
A recent raft of regulatory and legislative actions could weaken current state standards around the management, storage, and disposal of hazardous wastes, experts warn.
In December, for example, the Department of Toxic Substances Control’s (DTSC) oversight board approved the agency’s new hazardous waste management plan, needed, industry interests said, to streamline overly burdensome regulations. But environmental justice groups argue the plan is a deregulatory effort that could open the door to the DTSC ceding some of its important oversight authority.
As Aguirre sees it, unincorporated Kettleman City has been let down by all forms of government, from the feds all the way down to the county level. “They’re partnering with state agencies in supporting these toxic waste companies, and it leaves the communities even more vulnerable than they already are,” she said.
At the same time, some disadvantaged communities see tentative signs for hope. River Rouge, Detroit
Vicki Dobbins has lived all her life in and around the River Rouge district of Michigan, which sprung up more than a century ago when neighboring Detroit first laid down its roots as the birthplace of the nation’s automotive industry.
Perched on the banks of the Detroit River, a major industrial transportation corridor, River Rouge remains in the thrall of big business, with steel manufacturing plants and oil refineries dominating a concrete metropolis of a skyline. As researchers out of the University of Michigan noted during a 2023 toxic tour of the area, “no matter if you are in a community park, school backyard, or just walking down the street, evidence of heavy industry is impossible to ignore.”
With this industrial backdrop comes pollution — lots of it. Indeed, River Rouge is in one of the most environmentally burdened zip codes in the whole of Michigan, the area surrounded by 42 facilities that routinely emit a hazardous cocktail of pollutants.
“You become paranoid — it becomes a natural, normal thing for you to worry about,” said Dobbins about living in a region that has some of the worst air quality in the state and routinely exceeds federal air quality standards. A constant foul smell pervades Dobbins’s home. “When you get in your car, you roll your windows all the way up. You turn the air on,” she said. “It becomes like a habit.”
Long-term exposures to common air pollutants in the area, like benzene and sulfur dioxide, bring serious health implications. Residents live in an area with higher-than-average cancer risks and cancer rates. Breathing problems are rife, said Dobbins. “I keep my inhaler with me at all times,” she said.
“A young man died about three weeks ago from an asthma attack,” Dobbins added. “How in the world are young people dying in 2026 from an asthma attack? I thought we had all the answers.”
After decades of pushing back against the omnipotent presence of heavy industry, local residents got a major boost earlier this year when the U.S. District Court for the Eastern District of Michigan ordered DTE Energy Company and three of its subsidiaries to pay a $100 million penalty for non-compliance with the federal Clean Air Act at a local coke battery. The lawsuit was initiated by the EPA under the Biden administration.
Their emissions, the court found, were responsible for causing a host of health problems including asthma and heart attacks, strokes, and increased blood pressure, and they increased the likelihood of local residents getting cancer and Alzheimer’s disease, and suffering early deaths.
As part of the court’s determination, the defendants are required to spend $20 million over the course of seven years (with $5 million in the first three years) on local projects to help repair the damage they’ve caused. The air quality improvement projects could include installing HEPA air purifiers in nearby homes and air filtration systems in schools.
Dobbins, a member of the Sierra Club, sees the decision as a vindication for all the work she and others in the local environmental justice movement have put into fighting for a cleaner, healthier community. Their work has involved protests, marches, educational tours, and meetings with regulators and regional polluters.
“I feel really good because someone is finally paying attention,” said Dobbins. “The work we have been doing has not been in vain. As long as we continue to bring awareness to the judges, to the community, to the politicians, one day we will finally win this fight.”
That lawsuit, however, was initiated in 2022 under the previous administration. Experts who watch the current DOJ’s enforcement approach to federal environmental violations, and who are similarly keeping track of the administration’s broader deregulatory sweep, fear the long-term ramifications from these actions won’t be felt fully for a few years.
Dobbins is one of those braced for the long game.
“It takes a long time,” Dobbins said, of the work of community organizing. “I’ve been doing this for 20 years already. We’ve just got this. It’s going to take another 20 years before we get to the next step. I hope not. But it’s a slow process. And we’re fighting huge, huge, huge industry. Huge industry looks at little people and says, ‘we don’t care about you.’”
This article is licensed under Creative Commons (CC BY-NC-ND 4.0), and you are free to share and republish under the terms of the license.
Dan Ross Dan Ross is a journalist whose work has appeared in Truthout, The Guardian, FairWarning, Newsweek, YES! Magazine, Salon, AlterNet, Vice and a number of other publications. He is based in Los Angeles. Follow him on Twitter: @1danross.
Thursday, May 21, 2026
Aerosols and clouds in polluted regions grow faster
Researchers have found a possible explanation for the slower rate of global warming in Asia and Africa.
Leibniz Institute for Tropospheric Research (TROPOS)
Based on satellite measurements from space, the Indian subcontinent is regarded as a ‘hole in global warming’, as India is warming at only about half the rate of the global average. A possible explanation for this phenomenon is now provided by a new study on regional differences in the hygroscopic growth of particles. It highlights the importance of in-situ measurements, such as those carried out during the “BIOCAT-IIOE-2” measurement campaign on the FS SONNE 2024’s SO305 expedition in the Bay of Bengal.
Leipzig. Aerosols and clouds play a key role in the Earth’s climate budget. However, the extent to which they reflect solar energy depends heavily on how much water the particles can absorb. This so-called hygroscopicity has so far been represented in a simplified manner in climate models. An international research team led by the Leibniz Institute for Tropospheric Research (TROPOS) has now demonstrated through a global study that the models are not precise enough, particularly in urban regions. In chemically complex and polluted regions such as Delhi or Cairo, there is likely to be greater hygroscopic growth and higher water uptake, which could partly explain the observed regional cooling trends or the slower warming on the Asian and African continents, the researchers write in the journal Communications Earth & Environment, published by the Nature Publishing Group.
Particles in the atmosphere have a significant impact on the Earth’s radiation balance: on the one hand, these aerosols directly reflect sunlight and thermal radiation. On the other hand, they also act as cloud condensation nuclei. The amount of water vapour that adheres to the particles has a major effect on cloud formation. The hygroscopicity of aerosols (κ) is one of the key parameters in calculations of radiative forcing and influences the uncertainties in climate projections. Although cloud condensation nuclei have been studied for a long time, the hygroscopic growth of aerosols at sub-saturated conditions remain poorly characterised, particularly in remote and pristine regions.
To address these gaps in knowledge, the researchers developed a method using explainable machine learning (ML) to estimate the size-dependent κ in various atmospheric environments, incorporating observations from ten sites and across several particle sizes ranging from 50 to 300 nanometres. By integrating chemical composition, particle number size distribution and meteorology, the complexity of aerosol mixing states could be captured whilst simultaneously enabling the imputation of data gaps. “Unlike previous regional ML studies, our approach was extended and evaluated using geographically diverse and regionally resolved datasets, thereby improving predictive accuracy and interpretability,” explains Shravan Deshmukh from TROPOS. Machine learning allowed more data to be analysed than usual, and a wide range was covered through a diverse array of measurements. Hygroscopicity measurements using Hygroscopicity Tandem Differential Mobility Analysers (HTDMA) at ground stations span several continents and over a decade: Beijing (China, 2016/17), Cairo (Egypt, 2019/20), Delhi (India, 2020), Goldlauter (Germany, 2010), Henties Bay (Namibia, 2017), Houston (USA, 2021/22), Mahabaleshwar (India, 2020), Melpitz (Germany, 2015), Paris (France, 2022) and the Atlantic (R/V Polarstern, 2011/12).
A significant influence of externally mixed particles on κ was observed, particularly in urban and populated areas where new emissions interact with aged aerosols. “In heavily polluted regions such as megacities in Egypt or India, the particles are likely to grow faster and absorb more water. This could explain why these regions warm up less quickly. Increased hygroscopic growth in such regions also has potential implications for public health due to smog, as we were able to demonstrate through drone measurements in Delhi,” explains Dr Ajit Ahlawat, Assistant Professor at TU Delft. In such areas, conventional models exhibit the greatest errors, as they assume ideal internal mixing and disregard size and source variabilities. This underscores the importance of the chemical composition of the particles. As early as 2023, the team was able to show that, on a global average, hygroscopicity is essentially determined by the proportion of organic and inorganic substances in the aerosol composition.
Building on previous work, our regional estimates provide an improved, data-driven representation of aerosol hygroscopicity. This approach leads to more accurate estimates of negative radiative forcing and offers an alternative to conventional uniform parameterisations,” emphasises Prof. Mira Pöhlker of TROPOS and the University of Leipzig. “Our results highlight the importance of region-specific aerosol parameterisations as a crucial step towards reducing uncertainties in the estimation of direct radiative forcing in next-generation climate models. The use of estimates such as ours can typically alter regional direct radiative forcing by up to ±0.1 watts per square metre, which would be significant on a global scale.” The researchers, therefore, now hope that their new algorithm will be integrated into global models, which could potentially alter both the magnitude and the sign of aerosol-radiation interactions. This could make future climate models more accurate. Tilo Arnhold
Smog over Kathmandu, Nepal. The metropolis of millions, situated in a valley basin in the Himalayas, is considered one of the cities with the highest levels of air pollution worldwide
Credit
Ajit Ahlawat, TU Delft
The burning of fields is one of the causes of the severe air pollution over India.
Credit
PC Garima Shukla, TROPOS
Artistic representation of regional influences at a global scale. The figure shows a machine learning framework for estimating the hygroscopicity of aerosols using data from multiple locations, taking into account region-specific influences on radiative forcing worldwide.
Credit
Shravan Deshmukh, TROPOS (using Adobe Express and AI)
