Latest news with #Earth'sFuture
Chicago Tribune
2 days ago
- Science
- Chicago Tribune
Conservation practices needed to protect Illinois farmers as topsoil loss increases, experts say
As the deadline approaches for Congress to renew the U.S. Farm Bill, agricultural experts and farmers are calling on legislators to prioritize protecting topsoil in the Midwest and throughout the country, especially as the federal government is withdrawing from conservation initiatives. Topsoil is eroding, on average, at a rate of three-quarters of an inch per year in the Midwest, a rate double what the U.S. Department of Agriculture considers sustainable, according to a 2022 study published in the journal Earth's Future. The study also concluded more than 57 billion metric tons of topsoil have eroded in the Midwest over the last 160 years. 'Not to sound alarmist, but we rely and a lot of the world relies on the Midwest producing a lot of food,' said Evan Thaler, a geological researcher who helped author the study. 'Fertilizing crops can't keep up with the amount of productivity that's lost by erosion.' Topsoil contains living microorganisms and decaying plant roots that are important for productive crop growth. Excessive topsoil erosion can lead to a decrease in soil fertility levels and a decline in potential crop yields. No-till and reduced tillage farming, as well as cover crops, are among the best ways to counter topsoil erosion, experts say, especially as climate change has led to increased rainfall intensity. But under the Trump administration, federal support for these practices could be dramatically reduced. Some experts, including Andrew Margenot, an associate professor of crop sciences at the University of Illinois, have expressed skepticism about the figures in the study, particularly as they relate to erosion rates in Illinois. But Margenot called topsoil erosion a 'silent killer' whose worst effects may not become apparent for decades. Thaler said erosion rates aren't expected to be as severe in areas with flatter landscapes like much of Illinois. 'So it's not the whole landscape that's eroding quickly,' Thaler said of the Midwest. 'It's just portions of the landscape, but those portions of the landscape are eroding quite fast.' Regardless, experts agreed that excessive topsoil loss is an issue that poses long-term risks for the Midwest and requires assistance for farmers looking to implement conservation farming practices. 'It (erosion) is a way that we destroy really what is the best resource we have in this state,' Margenot said. 'We have a lot of wind, a lot of coal, etc., but we also have the best soils in the world.' Tillage clears crop residue from fields after harvesting and helps prepare the soil for seeding. The USDA notes that conventional tillage practices are most intensive on the soil and can increase the likelihood of erosion and nutrient runoff into waterways. In contrast, no-till and reduced tillage farming incorporate practices such as field mulching, crop rotation, as well as less-intensive tillage equipment. 'When they talk about 'conventional agricultural practices,' tillage is our No. 1 offender,' said Emily Hansen, a commercial agricultural educator with University of Illinois Extension. The 2018 Farm Bill — an omnibus bill that includes federal funding for conservation programs — is set to expire in September after having twice been extended by Congress. This reauthorization deadline comes after President Donald Trump immediately took steps to suspend funding under former President Joe Biden's Inflation Reduction Act on his first day back in office. Billions of dollars earmarked under the act for farming conservation practices were frozen. This funding freeze came at a time when the impacts of topsoil erosion are becoming more apparent in Illinois. High winds over recently tilled farm fields likely contributed to a massive dust storm in May, the first to affect the Chicago area in 40 years. In 2023, a dust storm in central Illinois caused 84 vehicles to crash on I-55, killing eight people and injuring at least 36. Such incidents have helped to renew debates on agriculture's role in hazardous weather events and further discussions on the importance of topsoil conservation. Others emphasize that soil conservation is important for the long-term economic outlook of the U.S. Cash crops, hidden costs'For decades, we have rightly focused on protecting our most vulnerable soils,' said Garrett Hawkins, president of the Illinois Corn Growers Association, in a statement. 'However, IL Corn encourages decision makers to think differently, to consider how programs can better protect our most productive soils.' The association is a farmer-led organization that represents the interests of Illinois corn farmers in Washington, D.C., and Springfield. 'Conserving our most productive acres is essential if we want to stay competitive in global markets,' Hawkins said. 'Modernizing our approach to conservation and creating programs that empower farmers to protect their most valuable soils with flexible and scalable solutions is vital. If we fail to deliver effective programs, technical assistance, and meaningful funding to our farmers, soil health and soil erosion will continue to be a challenge.' The association developed the Precision Conservation Management program, which collects data and helps farmers adopt conservation practices. 'What they've found over the last five years of data is that the most profitable fields in Illinois are doing no tillage with soybeans and one pass or less with corn,' Hansen said. In most cases, she said, data has shown there isn't an economic or agricultural benefit for corn farmers to do more than one tillage pass over their fields. According to data from the University of Illinois, 46% of soybean fields in Illinois had adopted no-till during the years of 2015 to 2017 but only 13% of cornfields. Illinois is the No. 1 producer of soybeans in the U.S. and the No. 2 producer of corn. 'Corn is a lot more challenging and that's where we see people doing those multiple tillage passes,' Hansen said. 'Corn, it needs good contact with the soil, so you do have to do some amount of tillage with it. But you know more than one pass is probably overdoing it a bit.' Among the first to get involved with PCM was Dirk Rice, a corn and soybean farmer in Champaign County. Rice said the genesis of Precision Conservation Management was the desire to help address farmers' financial concerns when adopting conservation practices. 'If you want a farmer to shift away from a practice that he knows has worked for him for 20, 30 years, there's always a concern of 'How does that affect me, financially?'' Rice said. 'And so the idea was, let's look financially at how farmers are doing this practice compared to this practice, compared to this practice,' he said. 'And I think after a decade or more of data, what we're seeing is the people that are doing less tillage are at least as profitable.' Rice, who said all of his soybean fields are no-till and over 80% of his corn fields are no-till or strip-till (a less intensive form of tillage), noted some difficulty in dealing with potential fungi that can grow in corn residue. He also said grain quality has declined in certain situations where he's no-tilled. Despite such challenges, Rice said soil conservation has been a tradition in his family for generations through practices like crop rotation, and it's a tradition he intends to continue. 'I'm sitting on ground my great-great-grandfather moved (to) in 1881,' Rice said. 'It's real personal to me that I leave that better than it was when I got here. And I think every generation in our family has felt the same way.' Rice added that fertilizer is a huge expense for his farm's operation and keeping soil nutrients in place helps with these costs and reduces runoff. 'Anything I can do to keep all my nutrients in place, that's how much less I got to turn around and buy next year or somewhere down the road. So that's a real no-brainer to me,' Rice said. Along with no-till and reduced tillage, cover crops — plants grown when the main cash crop isn't planted — can help keep topsoil 'anchored in place' and mitigate erosion and nutrient loss, Hansen said. She said cover crops such as cereal rye, which has a similar root structure to native prairie grasses, can help prevent nutrient and fertilizer runoff into streams and rivers that ultimately lead into the Gulf of Mexico. 'Cover crops have multiple benefits. They're tackling that erosion problem, they're tackling the nutrient loss,' Hansen said. 'So I like telling farmers to plant cover crops, but easier said than done.' Margenot noted that most farmland in Illinois is rented and not directly owned by the farmers who cultivate it, which can complicate efforts to plant cover crops. Less than a fourth of Illinois farmland is owned by the farmer who works the land, according to data from the Illinois Farm Business Farm Management, a nonprofit association that helps farmers make management decisions. 'They're not farmed by the owner, and a lot of times the landlord just wants a check,' Margenot said. 'They don't have a patience for cover crops because that digs into the net profit.' Margenot compared cover crops to adding another ball for a juggler and said they 'complicate the operation' for farmers. While great at reducing nitrate losses from fields, Margenot said, cover crops aren't 'that common in the Midwest,' especially in Illinois, because 'they don't really make you money.' 'When it comes to the bottom line, farms are businesses. They have mortgages to pay kids to send to college. Cover crops are not a great proposition,' Margenot said. 'I think they're great ecologically and I think that they, in the long term, probably have a positive ROI (return on investment) for the farm. But in the short term there's good evidence that cover crops aren't a great financial decision for a lot of operations.' Margenot said a comprehensive Farm Bill needs to incentivize farmers and landowners to plant cover crops given the associated costs and complications to farm operations. Thaler, the erosion study author, agreed. 'We need to be able to feed people,' he said. 'And unfortunately, if we don't start farming in a way that conserves our topsoil (and) really take approaches to allow farmers to experiment with conservation techniques, then I think we're going to be in some serious danger.' Among federal programs included in the Farm Bill is the Environmental Quality Incentives Program, which provides technical and financial assistance for farmers implementing conservation efforts. Jonathan Coppess, director of the Gardner Agriculture Policy Program at the University of Illinois, worked on legislation for the 2008 and 2014 Farms Bills. 'What EQIP does is the farmer goes out and takes on a practice that will reduce soil erosion, like a grass waterway for example so you get a washout spot in a field,' Coppess said. 'So the farmer will go out and get that done, and then about 75% of the expected cost of that would be reimbursed, if you will, by USDA through this EQIP program.' 'There's a lot of uncertainty around' the upcoming Farm Bill, Coppess said. 'There was a significant amount of funding provided by Congress in the Inflation Reduction Act, about $18 billion over multiple years for programs like EQIP, and the (Trump) administration froze a lot of that.' In April, a federal judge ordered the Trump administration to take immediate steps to reinstate this funding, citing a lack of authority on the part of the Departments of Energy, Housing and Urban Development, Interior and Agriculture, as well as the Environmental Protection Agency. Coppess described the short-term impacts of this funding freeze as 'potentially catastrophic' for farmers who spent money on conservation initiatives and who had expected reimbursement funding, especially if they had taken out a loan. 'If the administration eliminated whatever's remaining of that (Inflation Reduction Act) money, which may be as much as $12 billion, then over the long term that is a reduction in the investment in conservation,' Coppess said. 'We're investing in practices that will keep soil in the field, and get it out of the waterways, not have dust storms on the roads, those sort of things.' Coppess said 'every dollar that goes out the door' should have the priority focus of: 'Are we helping farmers deal with risk issues in farming that matter to the food supply?' Coppess said such an approach would require recalibrating crop insurance, repurposing subsidy funds for conservation and refocusing conservation funds on risk-based priorities; something he said wouldn't be easy and is 'a little idealistic for what we've seen in Congress recently.' Legislators need to focus more on how to address the long-term challenges faced by farmers, he said. 'Problem is that's not the conversation we're having,' Coppess said.
Yahoo
7 days ago
- Science
- Yahoo
New study targets past flooding as key to helping property owners assess climate threats
The number of structures at risk of flooding in the United States could be higher than previously thought, according to a study published Monday. The study, published Monday in the journal Earth's Future, found that 43% of flooded buildings in North Carolina between 1996 and 2020 were located outside the Federal Emergency Management Agency's Special Flood Hazard Area — areas that FEMA projects have a 1% risk of flooding in a given year. The findings could help more communities get a better handle on their flood risk and flood insurance needs, experts and authors of the study said. Flood insurance has become increasingly hard to get as some companies increase the price of policies or step back from insuring homes in certain markets due to more frequent and severe weather. That has left property owners more vulnerable. Experts told NBC News that with access to the right data sources, databases like the one described in the study could be developed nationwide. FEMA's maps are the main source nationally to identify flood-prone areas and what structures need to be insured. But experts say the system is outdated and has low resolution. The 100-year flood plain projection doesn't paint a complete picture of what areas are likely to flood. And climate change has rendered previously authoritative weather and climate projections less reliable, the authors noted. The study's use of address-level data allowed the researchers to pinpoint specific buildings that had flooded more than once. That information could help property owners know whether they should be purchasing flood insurance even outside of FEMA's flood hazard zones, experts said. In the U.S., 99% of counties have flooded at least once but only 4% of homeowners have flood insurance, according to FEMA. 'More information about where it has flooded in the past could help people make different decisions,' said Helena Margaret Garcia, the lead author of the study and a doctoral student at the University of North Carolina-Chapel Hill. FEMA and the National Flood Insurance Program did not return requests for comment. FEMA is currently in the process of redeveloping its flood mapping system, through an initiative called the Future of Flood Risk Data, that it says will provide a more comprehensive look at flood hazards and risks in the country using more efficient, accurate and consistent technology. As the planet warms, heavier rainfall is becoming more common because hotter air can hold more moisture, which later falls as rain. Climate change is also leading to a rise in global sea levels, which has made coastal and even some inland areas more vulnerable to flooding. Hurricane Helene, the third-deadliest hurricane of the modern era, caused severe flooding in mountainous areas in the middle of North Carolina. Damage totaled more than $78 billion, according to the National Oceanic and Atmospheric Administration. Severe rainfall has caused flash floods to rip through towns across the U.S. in the last two weeks, most recently on Monday in New Jersey and New York City. Extreme floods resulted in at least six deaths in North Carolina and more than 100 deaths in Texas. Flash floods are the top storm-related killer in the U.S. resulting in an average of 125 deaths per year in the last few decades, according to the National Weather Service A North Carolina climatologist said warmer ocean waters, which also feed storms, could have been a factor in fueling last week's Tropical Storm Chantal, which broke rainfall and river-crest records in the state. With the changing climate, having access to up-to-date maps is crucial, experts say. For the study, researchers mapped 78 flood events between 1996 and 2020 using data from the National Flood Insurance Program — the FEMA program through which property owners can purchase insurance for potential flood-related losses. They also used emergency service requests and 'volunteered geographic information,' which they acquired through social media posts, to create what they describe as a 'first of its kind' database. Data on past floods is often difficult for the general public to access, which can make it challenging for homeowners to know whether their property has previously flooded, experts said. Garcia said researchers can use the same methods from the study to create similar historical maps for regions across the nation to help officials identify areas in their state they may not have previously thought of as a flood risk. While the study found that only 20,000 of the 90,000 buildings flooded more than once — more than double the number of buildings that filed NFIP claims — authors of the study are working on research to quantify its human impact. Some are looking at health outcomes, including how a flood might interrupt people's health care, and others looking into the quantity of displacement due to the repetitive flooding, Garcia said. Antonia Sebastian, an assistant professor in the department of geological sciences at UNC-Chapel Hill, said the study aims to create a 'comprehensive record of past flooding' by gathering data on flood events that don't make the biggest headlines but still have an impact on homeowners. 'Places that have flooded before will flood again. It's just a matter of time,' Sebastian said. 'And those are all risky places.' Chad Berginnis, the executive director of the Association of Flood Plain Managers who wasn't involved in the study, said FEMA's maps are designed to implement the NFIP by determining what areas have to purchase flood insurance, using the 100-year flood plain as a guide. He said the study's analysis of historical flooding highlights that officials may need to require flood insurance in areas outside of FEMA's flood hazard zone. 'FEMA flood maps are a starting point and not an end point,' Berginnis said. 'They will show you one kind of flood risk, but if you want a total perception of flood risk, one of the things you got to do is find historical flood information.' He said replicating similar database models as the one described in the study in other local areas could help flood plain managers increase awareness among their communities about who is at risk of flooding by pinpointing where it has occurred previously. 'Just given the flood history of [the Guadalupe River], and having a daughter of the age that's going to camps too, I mean, this is really hitting home to me. You know, how is it that we, that societally, we're not comprehending that these same locations can also be very risky areas and not either demanding or finding out a little bit more about it. So, I think clearly we don't have enough awareness of flood risks.' June Choi, a doctoral student in earth system science at Stanford University who was not part of the study, said the finding that many flooded buildings were located outside of at-risk areas designated by FEMA's flood maps is likely the case across all states. The new database may be limited because it doesn't factor in how building density changes over time. But its use of historical records and address-specific data still make it a valuable resource for assessing future flood risk, she said. This article was originally published on
NBC News
15-07-2025
- Science
- NBC News
New study targets past flooding as key to helping property owners assess climate threats
The number of structures at risk of flooding in the United States could be higher than previously thought, according to a study published Monday. The study, published Monday in the journal Earth's Future, found that 43% of flooded buildings in North Carolina between 1996 and 2020 were located outside the Federal Emergency Management Agency's Special Flood Hazard Area — areas that FEMA projects have a 1% risk of flooding in a given year. The findings could help more communities get a better handle on their flood risk and flood insurance needs, experts and authors of the study said. Flood insurance has become increasingly hard to get as some companies increase the price of policies or step back from insuring homes in certain markets due to more frequent and severe weather. That has left property owners more vulnerable. Experts told NBC News that with access to the right data sources, databases like the one described in the study could be developed nationwide. FEMA's maps are the main source nationally to identify flood-prone areas and what structures need to be insured. But experts say the system is outdated and has low resolution. The 100-year flood plain projection doesn't paint a complete picture of what areas are likely to flood. And climate change has rendered previously authoritative weather and climate projections less reliable, the authors noted. The study's use of address-level data allowed the researchers to pinpoint specific buildings that had flooded more than once. That information could help property owners know whether they should be purchasing flood insurance even outside of FEMA's flood hazard zones, experts said. In the U.S., 99% of counties have flooded at least once but only 4% of homeowners have flood insurance, according to FEMA. 'More information about where it has flooded in the past could help people make different decisions,' said Helena Margaret Garcia, the lead author of the study and a doctoral student at the University of North Carolina-Chapel Hill. FEMA and the National Flood Insurance Program did not return requests for comment. FEMA is currently in the process of redeveloping its flood mapping system, through an initiative called the Future of Flood Risk Data, that it says will provide a more comprehensive look at flood hazards and risks in the country using more efficient, accurate and consistent technology. As the planet warms, heavier rainfall is becoming more common because hotter air can hold more moisture, which later falls as rain. Climate change is also leading to a rise in global sea levels, which has made coastal and even some inland areas more vulnerable to flooding. Hurricane Helene, the third-deadliest hurricane of the modern era, caused severe flooding in mountainous areas in the middle of North Carolina. Damage totaled more than $78 billion, according to the National Oceanic and Atmospheric Administration. Severe rainfall has caused flash floods to rip through towns across the U.S. in the last two weeks, most recently on Monday in New Jersey and New York City. Extreme floods resulted in at least six deaths in North Carolina and more than 100 deaths in Texas. Flash floods are the top storm-related killer in the U.S. resulting in an average of 125 deaths per year in the last few decades, according to the National Weather Service A North Carolina climatologist said warmer ocean waters, which also feed storms, could have been a factor in fueling last week's Tropical Storm Chantal, which broke rainfall and river-crest records in the state. With the changing climate, having access to up-to-date maps is crucial, experts say. For the study, researchers mapped 78 flood events between 1996 and 2020 using data from the National Flood Insurance Program — the FEMA program through which property owners can purchase insurance for potential flood-related losses. They also used emergency service requests and 'volunteered geographic information,' which they acquired through social media posts, to create what they describe as a 'first of its kind' database. Data on past floods is often difficult for the general public to access, which can make it challenging for homeowners to know whether their property has previously flooded, experts said. Garcia said researchers can use the same methods from the study to create similar historical maps for regions across the nation to help officials identify areas in their state they may not have previously thought of as a flood risk. While the study found that only 20,000 of the 90,000 buildings flooded more than once — more than double the number of buildings that filed NFIP claims — authors of the study are working on research to quantify its human impact. Some are looking at health outcomes, including how a flood might interrupt people's health care, and others looking into the quantity of displacement due to the repetitive flooding, Garcia said. Antonia Sebastian, an assistant professor in the department of geological sciences at UNC-Chapel Hill, said the study aims to create a 'comprehensive record of past flooding' by gathering data on flood events that don't make the biggest headlines but still have an impact on homeowners. 'Places that have flooded before will flood again. It's just a matter of time,' Sebastian said. 'And those are all risky places.' Chad Berginnis, the executive director of the Association of Flood Plain Managers who wasn't involved in the study, said FEMA's maps are designed to implement the NFIP by determining what areas have to purchase flood insurance, using the 100-year flood plain as a guide. He said the study's analysis of historical flooding highlights that officials may need to require flood insurance in areas outside of FEMA's flood hazard zone. 'FEMA flood maps are a starting point and not an end point,' Berginnis said. 'They will show you one kind of flood risk, but if you want a total perception of flood risk, one of the things you got to do is find historical flood information.' He said replicating similar database models as the one described in the study in other local areas could help flood plain managers increase awareness among their communities about who is at risk of flooding by pinpointing where it has occurred previously. 'Just given the flood history of [the Guadalupe River], and having a daughter of the age that's going to camps too, I mean, this is really hitting home to me. You know, how is it that we, that societally, we're not comprehending that these same locations can also be very risky areas and not either demanding or finding out a little bit more about it. So, I think clearly we don't have enough awareness of flood risks.' June Choi, a doctoral student in earth system science at Stanford University who was not part of the study, said the finding that many flooded buildings were located outside of at-risk areas designated by FEMA's flood maps is likely the case across all states. The new database may be limited because it doesn't factor in how building density changes over time. But its use of historical records and address-specific data still make it a valuable resource for assessing future flood risk, she said.
The Hindu
24-06-2025
- Science
- The Hindu
Rising evaporative demand spotlights India's data and research gap
M. S. Kukal, M. Hobbins,'Thirstwaves: prolonged periods of agricultural exposure to extreme atmospheric evaporative demand for water', Earth's Future, March 20, 2025. The air itself has become more thirsty due to global warming. Quenching this thirst has meant more water is coming off the land, including from plants and trees, leaving them drier. Evaporative demand is a measure of how thirsty the atmosphere is. Meetpal Kukal of the University of Idaho and Mike Hobbins of the University of Colorado and the U.S. National Oceanic and Atmospheric Administration coined the term 'thirstwave' to denote three or more contiguous days of intense evaporative demand — which they recently found to be increasing over the U.S. Their research was published in Earth's Future, where they wrote: 'Not only have thirstwaves increased in severity, but the likelihood of no thirstwaves occurring during the growing season has significantly decreased.' More water leaving While heat waves are caused by particular temperature and wind patterns, a thirstwave is the product of temperature, humidity, solar radiation, and wind speed. When temperatures rise, the consequences include more heat as well as the mechanics of water exchange between land and atmosphere, which in turn alters humidity, wind, and solar radiation. 'If you are a farmer growing rice or wheat, and your crop is irrigated sufficiently, its water use on any given day will be dictated by what the atmospheric evaporative demand is on that day,' said Mr. Kukal, assistant professor of hydrologic science and water management at the University of Idaho. Evaporative demand determines the near-maximum of how much water will evaporate from a given piece of land if sufficient water is available. In a warming world, the researchers found that thirstwaves have grown more intense, are more frequent, and are lasting longer, especially in seasons when crops are grown. While previous studies examined the mean or total evaporative demand, the new one focused on extremes. A simplified measure Mr. Kukal said evaporative demand is measured using standardised short-crop evapotranspiration — defined as the amount of water a grass surface 12 cm high and which has continuous access to sufficient water and is free of any stress will use (evapotranspiration itself refers to the two processes by which water moves from land to the atmosphere: evaporation from surfaces and transpiration from plant leaves.) Mr. Kukal called standardised short-crop evapotranspiration 'a core concept that is recommended to be used in deciding how much and when to irrigate a crop', adding that it is 'a simplification of [an] otherwise very complicated process, where we are assuming the vegetation properties to be constant, so water use is only a function of weather.' An increasing standardised short-crop evapotranspiration means the ambient temperature is increasing, the humidity dropping, wind speeds picking up, and the amount of solar radiation picking up as well. Effect of humidity In a paper published in Agricultural and Forest Meteorology in 1997, Nabansu Chattopadhyay and M. Hulme had suggested that both evaporation and potential evapotranspiration — the maximum amount of water that can be evaporated from any surface — decreased in India during the 30 years before the publication of their paper. However, they added, future warming was likely to lead to more potential evapotranspiration over the country, with regional and seasonal disparities. Chattopadhyay, who worked in the agricultural meteorology division of the India Meteorological Department (IMD), Pune, before his retirement, said that he and his co0author had analysed 30 years' worth of data from the IMD's network of evaporation stations and estimated potential evapotranspiration. But while warming over India should have increased evaporation, he added, their analysis found the opposite. When they rechecked the data, he said humidity had nullified the effect of rise in temperature. Using global circulation models, they also found that future temperature increases would supersede the effect of humidity and increasing evaporative demand. 'Great direction' In 2022, researchers from IIT-Roorkee, the National Institute of Hydrology (Roorkee) and institutes in France and The Netherlands, reported recent changes in evaporative demand across 100 river sub-basins in India. Their paper, published in the Journal of Cleaner Production, stated that 'the largest increase in actual evapotranspiration is found in Northern India, Western Himalayas, and several areas in Eastern Himalayas, which could be a sign of either increased vegetation or agricultural expansion.' This said, according to experts, there is essentially no data about extreme thirstwaves over India. 'The sensitivity of different crops, ecosystems, and regions to evaporative demand will likely be different, but this has not been investigated much yet. This is a great direction for future research,' Mr. Kukal said. A familiar pattern While Mr. Kukal's and Mr. Hobbins's study was the first to characterise thirstwaves in the U.S., Mr. Kukal said there is considerable scope to investigate this phenomenon in the Global South, where societies are generally more vulnerable to the consequences of climate change. As a step in this direction, Mr. Kukal is currently hosting Shailza Sharma, a PhD scholar from the National Institute of Technology, Jalandhar, to investigate thirstwave behaviour over South Asia with financial help from the Water Advanced Research and Innovation Program. They hope to publish their findings about thirstwaves in climate-vulnerable countries — with important implications for global food and water security — soon. One particularly intriguing aspect of their research is that they found that 'the worst thirstwaves happened in places that do not experience the highest [evaporative] demand.' This means there may be a need to reevaluate how governments prioritise different regions of their countries for climate change preparedness and climate mitigation, using the lens of thirstwaves. As the world warms further, tracking, measuring and reporting and sensitising farmers and water managers is of paramount importance, experts added. G.B.S.N.P. Varma is a freelance science journalist.
The Hindu
09-06-2025
- 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.
