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The Hindu
a day ago
- Science
- The Hindu
New study makes controversial weather-tweaking idea more realistic
The world needs to lower its dependence on fossil fuels. Countries have done so in fits and starts: issues like war, poverty, disease, and inflation have often left climate mitigation on the back burner. Today, greenhouse gas emissions are increasing worldwide. In this situation, some researchers have proposed the use of technologies to directly cool the planet rather than bank on reducing emissions alone. Stratospheric aerosol injection (SAI) is one such technology — and a controversial one. In SAI, aerosols are injected into the earth's stratosphere to reduce the amount of sunlight reaching the surface. A study recently published in the journal Earth's Future offered an innovative approach to this technique that could reduce its costs but also bring it closer to fruition despite the opposition to it. A volcano-inspired tool SAI is a 'proposed method of cooling the planet and reducing the impacts of climate change by adding a layer of tiny reflective particles to the high atmosphere,' Alistair Duffey, a PhD student at the Department of Earth Sciences at the University College London and the study's lead author, said. The method was inspired by volcanic eruptions, which have been known to have a cooling effect on the planet by spewing aerosols into the air. By reflecting more sunlight away from the earth, SAI aims to create a cooling effect that could help combat rising surface temperatures. How well SAI works depends on the type of material injected, the timing of the injection, and the location. Technical challenges are also more pronounced at higher altitudes. Most studies of SAI's efficacy have focused on implementing it at 20 km or more, particularly over areas closer to the equator. Doing so demands specially designed aircraft capable of operating at such elevations. A contrasting approach The study's authors have explored an alternative approach to undertake SAI using existing aircraft. 'We were interested in understanding how the effectiveness of stratospheric aerosol injection varies with the injection altitude,' Duffey said, adding that 'low altitude injection strategies are necessarily' meant for the polar regions. At the equator and regions close to the equator, the stratosphere is higher — 18 km and above — where existing aircraft can't fly. In polar and extratropical regions, the boundary between the troposphere (the lowermost layer of the atmosphere) and stratosphere, called the tropopause, is at a lower altitude than over the equator or subtropics. This means existing jets can reach the stratosphere at these close-to-polar regions. 'Higher altitude injection is generally more effective because the particles stay in the stratosphere for longer,' anywhere between months or years, Duffey said. In contrast, particles released at lower altitudes are more likely to be caught in clouds and washed out by rain. Despite this, researchers are exploring low-altitude SAI because spraying particles at lower heights is technically less challenging and doesn't require specially designed high-altitude aircraft, also making the approach potentially more accessible and cost-effective. Even when using existing aircraft for this mission, various modifications are necessary, according to Duffey. An August 2024 study said aircraft like the Boeing 777F would have to be modified to install insulated double-walled pressurised tanks to ensure the safe transport of aerosols and maintain the desired temperature during flight. Time-, cost-effective The new study's researchers simulated various particle-injection strategies. Using the UK's Earth System Model 1 (UKESM1), a computer model of the climate, they simulated the 'spraying' of sulphur dioxide at different altitudes, latitudes, and seasons. The team found that injecting 12 million tonnes of sulphur dioxide every year at an altitude of 13 km in the local spring and summer seasons of each hemisphere could cool the planet by approximately 0.6° C. The spray quantity is comparable to the amount added to the atmosphere by the Mount Pinatubo volcano in 1991. For cooling by 1° C, their models suggested spraying 21 million tonnes of sulphur dioxide a year. If the particles were injected at an even higher altitude in the subtropics, only 7.6 million tonnes would be required annually to achieve the same effect. An added advantage is that this technique could begin sooner than conventional higher altitude methods because designing and building specialised aircraft meant for flying 20 km and above requires almost a decade and several billion dollars in capital expenses. Modifying existing aircraft can be faster and cheaper. Is it worth the risk? But while there are some benefits to this method, using three times the usual amount of aerosols carries greater risk. 'There are lots of important risks and side-effects related to SAI, including social and geopolitical risks, as well as direct side-effects such as delayed recovery of the ozone hole and acid rain,' Duffey said. The cooling effect will also be more pronounced in polar regions rather than in the tropics, where warming is more severe. Duffey also stressed that the cooling effect wouldn't reverse climate change. The cooling may also have some other ecological effects but it would also introduce new challenges. As The Hindu reported recently, the cooling could mask warming on the ground and make countries complacent about curtailing emissions. SAI is also controversial because its effects are global: if one country injects aerosols into the stratosphere, all countries will be affected and not always in a good way. In 2021, the US National Academies of Sciences, Engineering, and Medicine recommended the US government fund solar geoengineering research with a focus on transparency. But a year later, an international coalition of scholars called for a moratorium on solar geoengineering R&D because the technology is 'ungovernable in a fair, democratic and effective manner'. Duffey also said the team's results were limited by the number of simulations they conducted and that they're working on a better follow-up study. Shreejaya Karantha is a freelance science writer.
Egypt Independent
5 days ago
- Politics
- Egypt Independent
As catastrophe looms, no one remembers Alexandria
In 1996, acclaimed novelist Ibrahim Abdel Meguid published, 'No One Sleeps in Alexandria,' which explored the relationships between local residents and migrants from the Delta and Upper Egypt during World War II. A similar title, 'No One Remembers Alexandria,' came to my mind after the city was hit by an unprecedented storm a few days ago, bringing torrential thunderstorms, snowfall, and strong winds. Over the past years, scientific warnings have consistently indicated that Alexandria is vulnerable to sinking, and the signs have already begun to appear. Yet, life proceeds normally, as if nothing is happening, until a severe storm finally does hit. Only then does everyone rush to speak out and issue warnings. During the COP27 Climate Change Conference, hosted in Sharm El Sheikh in 2022, climate scientists and global politicians, including then-British Prime Minister Boris Johnson, sounded the alarm that global cities, including Alexandria, face submersion if serious and swift action isn't taken. However, the severity of these warnings were downplayed to avoid public panic. A general feeling prevailed that things were under control and that plans were in place to address the issue. Just days ago, the Spanish newspaper 'El País' published a report quoting Egyptian experts who confirmed that despite scientific studies affirming rising sea levels, most Egyptians, especially in Alexandria, remain skeptical. Researchers stated that the changes are too gradual for the average citizen to notice, hence the lack of public engagement. Egyptian studies indicate that the sea level is rising by an average of 1.5 millimeters annually, while the land beneath Alexandria is sinking by a millimeter to a millimeter and a half each year. People don't notice this, and as such, they don't seem concerned. There's a strong focus on the present, with the future often left 'in God's hands.' The Spanish newspaper's report indicates that many Egyptians believe 'someone' will handle the issue when the time comes. I fear that if we continue to act this way, no one, no matter how capable or brilliant, will be able to manage the situation. The problem is no longer limited to severe winter storms and heavy summer heat. A scientific study published in the journal Earth's Future in February revealed a connection between housing collapses in Alexandria and climate change. We used to think collapses were solely due to unlicensed construction, contractor fraud, poor maintenance, and inadequate drainage infrastructure. However, while these issues occur in most Egyptian cities, property doesn't collapse at the same rate as in Alexandria. The study analyzed the reasons for 280 building collapses between 2001 and 2021, concluding that collapses are increasing and are linked to severe coastal erosion and rising sea levels. It also warned that 7,000 buildings in the city are at risk. The danger lies in the 'official and popular consensus' to downplay, or even deny, the impacts of climate change. Another study, involving interviews with 100 residents of the Al-Mex area, which is highly vulnerable to these changes, found that 90 percent have no plans to leave the area if negative developments occur. Only a small minority believe rising sea levels pose a threat. Seriousness is lacking, unfortunately. The majority are asleep regarding climate change in Alexandria. Author's bio Abdel Allah Abdel Salam is the managing editor at Al-Ahram newspaper where he writes a daily column titled 'New Horizon'. He holds a Bachelor's degree in Journalism from the Faculty of Mass Communication, Cairo University (1987). He began his journalistic career at Al-Wafd newspaper, then moved to the Middle East News Agency, before settling at Al-Ahram newspaper in June 1991. He founded the Al-Ahram electronic portal and served as its editor-in-chief from 2010 to 2013. He held the position of executive editor-in-chief of the Al-Masry Al-Youm website in 2013. Salam has also worked as managing editor of the Al Ain (UAE) portal in 2016, and managing editor of the 'Al-Watan' (Egyptian) newspaper's website in 2017.
NDTV
03-06-2025
- Science
- NDTV
Why Is The Historic Egyptian City Of Alexandria Crumbling? Study Explains
The Egyptian port city of Alexandria is crumbling, with buildings collapsing due to rising sea levels, a study has found. The historic city, known for being the birthplace of Cleopatra and housing the ancient Library of Alexandria, has witnessed 280 buildings collapsing in the past 20 years, owing to coastal erosion. More than 7,000 buildings are currently at risk of collapsing, according to the study published in the journal Earth's Future. Between 2014 and 2020 alone, 86 buildings completely crumbled, and 201 partially collapsed across the 2,300-year-old city, resulting in 85 deaths. "Collapses correlate with areas undergoing chronic and severe shoreline erosion and sea level rise, accelerating seawater intrusion in coastal aquifers," the study highlighted. For the study, scientists collected data through site visits, government reports, news archives and statements from private construction companies. Afterwards, they combined satellite imagery with historical maps from 1887, 1959 and 2001 to track shoreline movement. Additionally, the researchers analysed isotopes in soil samples to examine the effects of seawater intrusion. They measured isotopes like B7, whose higher levels indicate stronger, more stable soil, while lower levels suggest erosion. The crumbling is caused by seawater intruding into the groundwater under the city. As the saltwater moves inland due to rising sea levels, it increases groundwater levels beneath buildings and erodes the soil. "The true cost of this loss extends far beyond bricks and mortar. We are witnessing the gradual disappearance of historic coastal cities, with Alexandria sounding the alarm. What once seemed like distant climate risks are now a present reality," study co-author Essam Heggy, a water scientist at the University of Southern California's Viterbi School of Engineering. The scientists have proposed a nature-based solution to combat coastal erosion and seawater intrusion. They suggest creating sand dunes and vegetation barriers along the coastline to block encroaching seawater and prevent seawater intrusion. This way, the groundwater levels will not be pushed into building foundations.
NDTV
15-05-2025
- Science
- NDTV
Fake News Or Fact: UK's Sun-Dimming Experiment Explained
The UK government's 56.8 million pounds (Rs 578 Crore) investment in geoengineering trials, specifically solar radiation management (SRM) to reflect sunlight and combat climate change, has triggered a surge of misinformation online, according to Euronews. Claims that the UK is secretly "dimming the sun" to control the population are false and linked to the debunked "chemtrails" conspiracy. While the government will be testing sun-reflecting particles in the stratosphere, experts have stated that this can not be done in secret. They also noted that this is not to be confused with cloud seeding. SRM aims for long-term manipulation to create balance, whereas cloud seeding increases precipitation, as per the Euronews. According to BBC, in a study published in Earth's Future, scientists at University College London show that SAI could be achieved using existing aircraft injecting aerosols at an altitude of 8 miles high instead. To inject at this lower altitude, three times more aerosol would be needed to be as effective, and it would strongly increase side effects such as acid rain. Public perception of such techniques is also going to be a challenge, primarily due to the widely known conspiracy theory of 'chemtrails'. What's a Fact: The UK government is funding geoengineering research to explore its potential in slowing global warming. The experiments will study the feasibility of reflecting sunlight using particles in the stratosphere. What's Fake: Claims that the UK has been secretly conducting geoengineering experiments for years to control the population. The "chemtrails" conspiracy theory, which suggests planes are spraying harmful chemicals over the public. Experts emphasise that large-scale weather modification experiments cannot be conducted in secret, and the UK's research aims to provide crucial data on geoengineering's potential.
Scientific American
02-05-2025
- Science
- Scientific American
Solar Geoengineering Is Possible with Existing Aircraft, Study Finds
CLIMATEWIRE | A futuristic geoengineering proposal might be easier to accomplish in the real world than scientists previously thought. New research suggests that a planet-cooling strategy known as solar radiation management is already possible with existing commercial airplanes. Until now, many experts suggested the technology probably would require specialized high-altitude aircraft. And assembling a large enough fleet of these machines could take a decade or more. The new study, published Monday in the scientific journal Earth's Future, makes the case that solar geoengineering — currently a hypothetical strategy — could overcome the vehicle hurdle without a major technological leap. On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. But the concept remains deeply controversial among both scientists and climate activists. And the new study's authors cautioned the strategy needs more study before world leaders move forward. 'We need to know more, we need to do more research,' said lead study author Alistair Duffey, a Ph.D. student at University College London, in an interview with POLITICO's E&E News. 'There are huge risks and huge uncertainties that require a concerted effort from the research community to tackle before it would make sense to have any kind of opinion about doing this in the real world.' Most climate experts agree that solar geoengineering is not a substitute for reducing emissions, he added. Phasing out fossil fuels and curbing greenhouse gases remain the primary strategies for tackling climate change. Even so, solar geoengineering is gaining global attention — from both advocates and critics — as Earth's temperatures continue to rise. World leaders so far have failed to curb greenhouse gases at the speed necessary to align with the Paris Agreement's international climate goals. Some advocates argue that geoengineering eventually could become a necessary strategy to cool the planet, and that researchers must keep studying its potential. But other experts warn that too much focus on geoengineering could distract world leaders from their progress on reducing emissions. And some worry that it could increase the risk of a country or company going rogue and attempting a large-scale geoengineering project without global cooperation. The new study doesn't make any arguments for or against geoengineering as a climate intervention. Instead, it explores scientific questions related to the technology the project would require — if it ever got to that stage. The most commonly discussed form of geoengineering hinges on a strategy known as solar aerosol injection — spraying reflecting particles into the atmosphere to beam sunlight away from the planet. Previous studies have suggested this strategy would work best at very high altitudes, where the particles have the longest lifetime in the atmosphere. At lower altitudes, they're less effective and fall out of the air faster. Research suggests the most effective height for particle spraying is around 12.5 miles above the surface of the Earth. But most existing aircraft can't safely fly at that altitude. That means any future large-scale geoengineering operation would require a fleet of specially designed planes, which could take years to develop. But the new study suggests effective geoengineering still could be possible at lower altitudes. Using a computer model designed to simulate the Earth system, Duffey and his colleagues ran a series of experiments comparing the effects of aerosol injections at different altitudes, latitudes and times of the year. They found that conditions for low-altitude particle spraying were most favorable closer to the Earth's poles, where the shape and thickness of the Earth's atmosphere is slightly different than it is closer to the equator. They also found that spring and summer were the best seasons, when there's more sunlight for the particles to reflect. These experiments were still far less efficient than high-altitude injections, the study noted. In fact, they're only about 35 percent as effective as similar projects conducted at the recommended 12.5 miles high in the subtropics. But they still could make a meaningful dent in the Earth's temperatures at just 8 miles above the surface of the Earth — a height that's safe for many commercial aircraft. The simulations found that spraying 12 million metric tons of reflective sulfur dioxide into the atmosphere at 8 miles altitude and 60 degrees latitude in the spring and summer would result in about 0.6 degree Celsius, or 1.08 degrees Fahrenheit, of global cooling. The concept still needs more research, though, the study authors cautioned. Particles in the atmosphere tend to diffuse more quickly from east to west than they do from north to south, meaning the immediate effects of solar geoengineering deployed at high latitudes might be stronger at the poles than at the equator. In theory, that could be useful for purposes like refreezing sea ice or slowing the melting of the world's ice sheets. But many of the countries most vulnerable to the impacts of climate change are located in the tropics, the authors noted. If world leaders one day consider geoengineering for the good of the planet, a polar injection strategy might mean that regions closer to the equator wouldn't benefit as strongly. At the same time, a low-altitude injection strategy, with particles sprayed closer to the surface of the Earth, could carry the risk of stronger, unintended side effects. Some studies have suggested that solar geoengineering could have unwanted impacts on the Earth's ozone layer or precipitation patterns, and those potential consequences still need more research. The team hopes to address some of these questions in future studies, Duffey suggested. For now, the new research adds another data point to help answer scientific questions about the potential risks and benefits of geoengineering. 'It doesn't avoid the need for climate action,' Duffey cautioned, noting that reducing carbon emissions is still the most important strategy for addressing climate change. 'It would be very, very scary, very risky, to be living in a world that just offsets more and more of the greenhouse-gas-forced warming with more and more reflecting of sunlight,' he said. 'That's not a world we want to live in.'
