Latest news with #CommunicationsEarth&Environment
The Hindu
5 days ago
- Science
- The Hindu
Some cities in northwest, northern Indo-Gangetic Plain shielded from long-range aerosol pollution
A study of 141 cities in India from 2003 to 2020 using satellite-retrieved aerosol data reveals a surprise — aerosol levels were significantly high in 57% of cities compared with the surrounding areas outside the city in south and southeast India, while the converse was true in the case of 43% of cities in northwest and northern Indo-Gangetic Plain (IGP) region where the aerosol levels were relatively lower in the cities compared with the surrounding areas. Researchers at the School of Earth, Ocean and Climate Sciences, IIT Bhubaneswar, refer to the cities in south and southeast India that show higher aerosol levels than the surrounding areas as Urban Aerosol Pollution Islands. And cities that show relatively lower aerosol levels compared with the surrounding areas are referred to as Urban Aerosol Clean Islands. In the case of cities referred to as urban aerosol clean islands, the aerosol levels were not uniformly higher in the surrounding areas compared with the city. Instead, the levels were higher in the areas southwest of the city, which are located upstream of the dust flow, while the northeast side of the city located downstream of the dust flow showed less aerosol levels which almost matched the levels seen in the city. 'Aerosol coming from outside wasn't adding to the pollution already seen in the cities that we refer to as urban aerosol clean islands. Instead, the cities in northwest and in the northern Indo-Gangetic Plain region were stopping or diverting the incoming aerosol and moving it around the city. We observed areas upstream of the aerosol flow had more aerosol load than the city, while the areas northeast of the city that were located downstream of the flow had less aerosol load. It is a trail going actually downwind for some distance,' says Dr. V. Vinoj from IIT Bhubaneswar, and the corresponding author of a paper published on July 16, 2025 in the journal Communications Earth & Environment. 'We didn't expect this.' 'North Indian cities, despite being blamed for poor air quality, are found to have no consistent 'pollution domes'. Instead, we observed urban clean islands —zones with relatively lower aerosol levels than surrounding areas. We hypothesise this unexpected pattern to be linked to a phenomenon known as urban wind stilling effect,' he said. Wind stilling effect Wind stilling effect refers to a weakening of surface winds across highly urbanised cities where the buildings and infrastructure reshape local climates, creating zones of atmospheric stagnation. These zones collectively lead to invisible barriers around the city (in the upwind regions), partially blocking the entry of long-range aerosol pollution, especially mineral dust from the nearby arid regions. Also, cities located in regions with high background pollution tend to slow down the transport of pollutants from outside the city, like the dust from Thar desert or aerosol from biomass burning that are transported from elsewhere. This results in cities having relatively less aerosol loading than the surrounding areas. 'While external sources still contribute to pollution, this barrier alters how pollutants accumulate and disperse, leading to a deceptive pocket of cleaner air within the city and its downwind regions. In contrast, southern Indian cities, with less influence from transported dust and different meteorology, show traditional pollution domes,' Dr. Vinoj explains. Less aerosol load According to Soumya Sethi, a Ph.D. scholar and the first author of the paper, the study makes it clear that the proposed barrier effect seen in cities does not eliminate pollutant transport into the city but only slows down the transport. In the process, the cities in the northwest and northern Indo-Gangetic Plain have relatively less aerosol load while the surrounding areas witness an increase in pollutant build up. The reason why cities in southern India do not have urban aerosol clean islands is because southern cities don't have any large source of pollutants coming from elsewhere to create a large aerosol background, which will allow us to see this rather invisible dome effect. Instead, we see the urban pollution island because cities are still the dominant source of pollutants, says Dr. Vinoj. The urban clean island effect was not studied during monsoon due to non-availability of data due to clouds and rain. The study looked at data for other seasons but found the urban clean islands effect was pronounced and clearly observable only during the pre-monsoon period. During other seasons, a large amount of dust or other sources of aerosols being transported long distances is not seen, making it difficult to see the urban aerosol clean islands effect clearly. 'The pre-monsoon time is when the signature is clear, and the urban clean islands effect becomes clearly visible,' he said. The urban clean island effect normally disappears during the post-monsoon but is again seen during winter because of dry conditions but not to the extent that is seen during the pre-monsoon period. Invisible barrier The study looked at the high dust case and no dust scenario and found the urban clean island effect became pronounced in many cities in northwest and northern Indo-Gangetic Plain in high dust case but not in the no dust scenario. 'Our hypothesis is that, irrespective of the season, whenever less transport of aerosol or pollution is happening, you will see urban pollution islands. But whenever the pollution transport from outside is enhanced, you will see a clean island effect,' Dr. Vinoj said. 'There is an invisible barrier that was not noticed earlier. This barrier is seen only when aerosols from biomass burning or dust are transported from elsewhere.' In fact, a few studies carried out over global megacities such as Shanghai, Atlanta and a few European cities have observed clean islands, but attributed it to emissions in suburban regions. 'These findings, we feel, challenge conventional understanding that long-range transported aerosols will always lead to more pollution over the cities and underscore the need for deeper scientific understanding into how urban growth and evolving micro-climates influence air pollution and its spatial patterns. Therefore, building truly sustainable, climate-resilient cities will depend on our ability to understand and anticipate these complex interactions as cities continue to expand,' he added.
Yahoo
5 days ago
- Science
- Yahoo
Toxic ‘forever chemicals' have infiltrated Antarctic waters: Study
The frigid waters that surround Antarctica may be inhospitable to human inhabitance, but they are churning with the manmade relics of toxic chemical production, a new study has found. Certain types of 'forever chemicals' are present in ocean areas west of the Antarctic Peninsula at levels comparable to those in the North Atlantic, according to the study, published in Communications Earth & Environment. These findings, the study authors stated, underscore the importance of considering persistence when weighing environmental risk, while shedding light 'on the impact of the larger pool of per- and polyfluoroalkyl substances,' also known as PFAS. There are about 15,000 types of these so-called 'forever chemicals,' many of which are linked to cancers and other serious illnesses. Known for their ability to linger in the environment, PFAS are found in certain firefighting foams and in a variety of household products, such as waterproof apparel, nonstick pans and cosmetics. Although previous studies have suggested only a limited presence of PFAS in the Southern Ocean, the authors — from Spain's Institute of Environmental Assessment and Water Research and the University of Barcelona — were able to challenge this assumption. The prevailing notion, they explained, reasoned that the 'circumpolar current' that flows clockwise around the Antarctic prevented the transport of PFAS southwards. Yet at the same time, the researchers recognized that oceans have become 'a major reservoir' of a PFAS subgroup called perfluoroalkyl acids (PFAAs) — and that certain precursors of PFAAs had been identified in the Southern Ocean's atmosphere. 'PFAAs are widely distributed in tropical and subtropical oceans and are extremely persistent in the environment,' the authors stated. Among the two most notorious types of PFAAs around the world are PFOA and PFOS — carcinogens that have largely been phased out of production but that remain in soil and water resources due to their longevity. To determine whether these persistent — and often toxic — types of PFAS had in fact infiltrated the Southern Ocean, the scientists conducted on-site water sampling in the area, accompanied by analytical procedures. In doing so, they identified PFAA concentrations in seawater at Antarctic latitudes of 71 degrees south comparable with those of 37 degrees north — in regions with known PFAS sources across Europe, the Mediterranean, Central Asia and the United States. Given the circumpolar current's likely role as 'a barrier for the north-south transport of PFAAs by oceanic currents,' the researchers focused on a possible mechanism called 'wet deposition,' when aerosolized pollutants fall from the atmosphere with rain or snow. The scientists ultimately determined that PFAA compounds are transported via ocean currents from the southern subtropical Atlantic to the sub-Antarctic — the zone immediately north of the Antarctic region. From there, what likely occurs is a phenomenon known as 'sea-spray mediated grasshopping,' in which PFAA-laden sea spray forms in the atmosphere and then deposits in the Southern Ocean, per the study. The Southern Ocean, the authors explained, is known for its high wind speeds, and the region in general endures 'incursions' of wet air masses from the north. Once the compounds have made it into the Antarctic region and have crossed a maritime barrier called 'the Antarctic divergence,' they are generally there to stay, the study found. This polar PFAS pileup, the authors warned, raises concerns about potential risks posed to the Antarctic ecosystem. They therefore stressed a need for further research into the prevalence of such 'persistent contaminants of emerging concern' across the region. 'This unexpected accumulation evidences the global risk posed by persistent chemicals,' the authors added. Copyright 2025 Nexstar Media, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.
The Hill
6 days ago
- Science
- The Hill
Toxic ‘forever chemicals' have infiltrated Antarctic waters: Study
The frigid waters that surround Antarctica may be inhospitable to human inhabitance, but they are churning with the manmade relics of toxic chemical production, a new study has found. Certain types of 'forever chemicals' are present in ocean areas west of the Antarctic Peninsula at levels comparable to those in the North Atlantic, according to the study, published in Communications Earth & Environment. These findings, the study authors stated, underscore the importance of considering persistence when weighing environmental risk, while shedding light 'on the impact of the larger pool of per- and polyfluoroalkyl substances,' also known as PFAS. There are about 15,000 types of these so-called 'forever chemicals,' many of which are linked to cancers and other serious illnesses. Known for their ability to linger in the environment, PFAS are found in certain firefighting foams and in a variety of household products, such as waterproof apparel, nonstick pans and cosmetics. Although previous studies have suggested only a limited presence of PFAS in the Southern Ocean, the authors — from Spain's Institute of Environmental Assessment and Water Research and the University of Barcelona — were able to challenge this assumption. The prevailing notion, they explained, reasoned that the 'circumpolar current' that flows clockwise around Antarctic prevented the transport of PFAS southwards. Yet at the same time, the researchers recognized that oceans have become 'a major reservoir' of a PFAS subgroup called perfluoroalkyl acids (PFAAs) — and that certain precursors of PFAAs had been identified in the Southern Ocean's atmosphere. 'PFAAs are widely distributed in tropical and subtropical oceans and are extremely persistent in the environment,' the authors stated. Among the two most notorious types of PFAAs around the world are PFOA and PFOS — carcinogens that have largely been phased out of production but that remain in soil and water resources due to their longevity. To determine whether these persistent — and often toxic — types of PFAS had in fact infiltrated the Southern Ocean, the scientists conducted on-site water sampling in the area, accompanied by analytical procedures. In doing so, they identified PFAA concentrations in seawater at Antarctic latitudes of 71 degrees south comparable with those of 37 degrees north — in regions with known PFAS sources across Europe, the Mediterranean, Central Asia and the United States. Given the circumpolar current's likely role as 'a barrier for the north-south transport of PFAAs by oceanic currents,' the researchers focused on a possible mechanism called 'wet deposition,' when aerosolized pollutants fall from the atmosphere with rain or snow. The scientists ultimately determined that PFAA compounds are transported via ocean currents from the southern subtropical Atlantic to the sub-Antarctic — the zone immediately north of the Antarctic region. From there, what likely occurs is a phenomenon known as 'sea-spray mediated grasshopping,' in which PFAA-laden sea spray forms in the atmosphere and then deposits in the Southern Ocean, per the study. The Southern Ocean, the authors explained, is known for its high wind speeds, and the region in general endures 'incursions' of wet air masses from the north. Once the compounds have made it into the Antarctic region and have crossed a maritime barrier called 'the Antarctic divergence,' they are generally there to stay, the study found. This polar PFAS pileup, the authors warned, raises concerns about potential risks posed to the Antarctic ecosystem. They therefore stressed a need for further research into the prevalence of such 'persistent contaminants of emerging concern' across the region. 'This unexpected accumulation evidences the global risk posed by persistent chemicals,' the authors added.
The Hill
7 days ago
- Health
- The Hill
China's success in cleaning up air pollution may have accelerated global warming: Study
Efforts to clean up air pollution in China and across East Asia may have inadvertently contributed to a spike in global warming, a new study has found. The decline in aerosol emissions — which can cool the planet by absorbing sunlight — have added about 0.05 degrees Celsius in warming per decade since 2010, according to the study, published on Monday in Communications Earth & Environment. At that time, China began implementing aggressive air quality policies and was ultimately able to achieve a 75 percent reduction in emissions rate of toxic sulfur dioxide, the authors noted. Sulfur dioxide gas, harmful pollutants that result from fossil fuel combustion and volcanoes, are precursors of sulfate aerosols, which are the dominant aerosol species that cool the Earth today. Despite posing health threats to plants, humans and other animals, these particles are among the many types of aerosols that also cool the planet. When clouds form around aerosols, such particles can absorb solar energy from the atmosphere and thereby reduce sunlight at ground level. And if clouds are not present, aerosols can reflect sunlight back into outer space. Before China's air quality improvement policies took effect, pollution was a leading cause of premature death in the country, the study authors noted. However, with fewer cooling aerosols now present in the atmosphere, areas of East Asia and around the world have endured intensified warming — and are expected to face even more extreme heat, shifting monsoon patterns and potential disruptions to agriculture, according to the study. The plunge in sulfate levels 'partially unmasks greenhouse-gas driven warming and influences the spatial pattern of surface temperature change,' the researchers observed. 'Reducing air pollution has clear health benefits, but without also cutting CO₂, you're removing a layer of protection against climate change,' co-author Robert Allen, a climatology professor at the University of California, Riverside, said in statement. 'It highlights the need for parallel efforts to improve air quality and reduce greenhouse gas emissions,' he said. Allen and his colleagues drew their conclusions based on simulations from major climate models for the years 2015 to 2049, using data from the Regional Aerosol Model Intercomparison Project, which includes contributions from the U.S., Europe and Asia. They projected a global, annual mean warming of about 0.07 degrees Celsius due to aerosol emissions reductions, with 0.05 degrees Celsius of warming per decade already occurring since 2010. Emissions reductions applied to their simulations corresponded closely with those realized over the 2010 to 2023 period in East Asia, the authors noted, adding that emissions from the region are expected to continue to decline — albeit at a slower rate. Although their work focused on sulfate aerosols, the researchers stressed that carbon dioxide and methane emissions remain the biggest drivers of long-term climate change. 'Our study focused on the recent, dramatic speedup in global warming, which is very concerning but still small compared to the overall, long-term amount of warming from increased CO2 and methane,' lead author Bjørn Samset, a senior researcher at the Center for International Climate and Environmental Research in Norway, said in a statement. Allen, meanwhile, also emphasized that because aerosols are short-lived in the atmosphere, the spike in global temperatures could subside in the near future. 'Sulfur dioxide and sulfate aerosols have lifetimes of about a week,' he said. 'Once they're removed, we'll eventually settle back into a warming rate that's more consistent with the long-term trend.' As other regions across the world, including South Asia, Africa and North America, begin to phase out aerosol emissions, the scientists said they plan to analyze how potential shifts could shape forthcoming climate trends. 'Air quality improvements are a no-brainer for public health,' Allen said. 'But if we want to prevent the worst impacts of climate change, we have to cut CO₂ and methane too. The two must go hand in hand.'
The Irish Sun
14-07-2025
- Science
- The Irish Sun
Map of Earth's underworld shows hidden ‘blobs' blamed for wiping out almost all life & killing the dinosaurs
MYSTERIOUS 'BLOBS' lurking beneath the Earth's surface could be responsible for the cataclysmic volcanic eruptions that helped kill off the dinosaurs. While an asteroid impact was the main force behind the demise of the dinosaurs, a chain of violent volcanic eruptions that followed the impact is also thought to have played a role. Advertisement 4 These so-called 'BLOBS' - which stands for big lower-mantle basal structures - lie thousands of kilometers below Earth's surface Credit: Cucchiaro et al., Communications Earth & Environment, 2025 4 While an asteroid impact was the main force behind the demise of the dinosaurs, a chain of violent volcanic eruptions that followed the impact is also thought to have played a role Credit: Getty 4 There are two giant 'BLOBS' that are both the size of continents hiding under the African and Pacific hemispheres, according to researchers Credit: Cucchiaro et al., Communications Earth & Environment, 2025 Volcanic eruptions can wipe out entire cities - just look at Pompeii - and even wipe out life on Earth. The source of these Earth-shattering eruptions can be traced back to specific features deep within Earth's underworld, called 'BLOBS', according to a new study. These so-called 'BLOBS' - which stands for big lower-mantle basal structures - lie thousands of kilometers below Earth's surface. And they move just like the tectonic plates above them. Advertisement READ MORE ON EARTH SCIENCE There are two giant 'BLOBS' that are both the size of continents hiding under the African and Pacific hemispheres, researchers said. Volcanologist Annalise Cucchiaro from the University of Wollongong in Australia, discovered these 'BLOBS' with her colleagues. They say these deep Earth structures have a direct influence on volcanic activity above ground. Giant volcanic eruptions occur when deep mantle plumes - scorching columns of rock - rise from nearly 3,000 kilometers below the surface. Advertisement Most read in Science Analysing three different datasets on large volcanic eruptions that occurred around 300 million years ago, the researchers concluded that the 'BLOBS' are the source of these plumes. "This work highlights the importance of mantle plumes in acting as 'magma highways' to the surface, creating these giant eruptions," Cucchiaro World's smallest volcano found by locals after bursting from ground in Peru "It also shows that these plumes move along with their source, the BLOBS." Although some mysteries remain - like whether the BLOBS are fixed in place or if they travel across the underworld. Advertisement "This research cracks open one of the questions that has long plagued scientists – are the BLOBS stationary or mobile and how do they relate to giant volcanic explosions – so it is a thrill to finally [be able] to unravel these mysteries," added geoscientist Nicholas Flament. What the new research suggests is that they are part of a dynamic system that has direct repercussions for all living things above ground. "We used statistics to show that the locations of past giant volcanic eruptions are significantly related to the mantle plumes predicted by our models," Cucchiaro and Flament wrote in "This is encouraging, as it suggests that the simulations predict mantle plumes in places and at times generally consistent with the geologic record." Advertisement With all the devastation volcanic eruptions can cause, it is important to know what causes them to blow. 4 Some mysteries remain - like whether the BLOBS are fixed in place or if they travel across the underworld Credit: Getty
