Latest news with #GeorgiaInstituteofTechnology
Miami Herald
14 hours ago
- Science
- Miami Herald
As the ocean warms, a new study found it's also changing color
For thousands of years, writers have come up with increasingly creative ways to describe the 'wine-dark sea.' But a new study suggests that modern poets may be faced with a slightly different palette. A study published Thursday in the journal Science found that the ocean is changing color as it warms. By analyzing satellite data from 2009 to 2022, researchers from Duke University and the Georgia Institute of Technology noticed that waters near the equator were getting greener, while areas near the poles were turning bluer. Lead author Haipeng Zhou calls it 'this greener greens or bluer blues phenomenon.' The culprit, the paper suggests, is the teeny tiny plant-like creatures that form the building blocks of the marine food web — phytoplankton. Phytoplankton are filled with a green pigment called chlorophyll that allows them to absorb energy from sunlight through photosynthesis. As waters near the equator warm, they're less hospitable to the microscopic critters, so the water appears bluer. At the poles, the colder water is far more nutrient-dense, so there's lots more phytoplankton to go around, giving the waters a rich, blue tinge. It's not a new phenomenon. There's a reason the Caribbean is known as the land of dazzling turquoise waters, while Arctic waters are a dark navy contrast to the ivory ice floes around them. But Zhou, who began the research at Duke University and completed it as a postdoctoral researcher at Georgia Tech, found that as the ocean warms, this phenomenon is getting stronger. Their study only looked at the open ocean, not coastal waters. Near the coast, there are plenty of complicating factors that make it hard to clearly point to phytoplankton as the main cause of color changes, like dirt and sand floating in the water, shifting winds, pollution or even seagrass die off. To understand the concentrations of phytoplankton, the research team relied on a National Oceanic and Atmospheric Administration database made up of samples scooped from various research cruises all over the world. This database, plus satellite imagery, helped show the color shift in different regions of the ocean. The changing levels of phytoplankton could be bad news for fish in the tropics, or for communities that rely on those fish. But it could also be a boon for their northern and southern cousins. 'We all know that phytoplankton is the bottom of the food chain. Any impact on phytoplankton will have impacts on its predators,' Zhou said. Phytoplankton need sun and nutrients to flourish, but when the ocean warms, the individual layers that make up the sea grow more stratified, so it's harder for phytoplankton to float up and down the water column to access the same light and nutrients they're used to, he said. So while scientists can clearly say that warmer waters lead to fewer phytoplankton, and they know that climate change is one of the main reasons the oceans are heating up, it's not clear if climate change is the reason for the color shift. 'We need longer records, 30 years, 40 years, to make us more confident whether it is linked to climate change or global variability,' Zhou said. The study only looked at about 20 years of data, which Zhou said is enough to confidently say that something has changed, but not long enough to know what caused that change. Other factors can and do affect water temperature, like the shift in trade winds over the Atlantic that led to a coral-killing marine heat wave in 2023. 'The study period was too short to rule out the influence of recurring climate phenomena such as El Niño,' wrote co-author Susan Lozier, Dean of the College of Sciences at Georgia Tech, in a statement. However, Zhou added, more research may very well find that this color-shifting trend continues into the future as human-caused climate change continues to heat up the oceans. 'The temperature of the water is rising. While there's no evidence showing that this progress will slow down, it's very likely we'll have warmer waters in the future, which means we'll have a continuous impact on the ocean ecosystem.'
San Francisco Chronicle
14 hours ago
- Science
- San Francisco Chronicle
How changing ocean colors could impact California
Earth's oceans have been getting greener at the poles and becoming bluer closer to the equator, according to a study published Thursday in Science. The shift reflects changes in marine ecosystems, which experts say could affect fish populations and create problems for fisheries, including in California. 'It has lots of potential implications for the way we use the ocean,' said Raphael Kudela, a professor of ocean sciences at UC Santa Cruz, who wasn't part of the new study. The scientists analyzed satellite data from 2003 to 2022 to track ocean concentrations of chlorophyll, a green pigment that phytoplankton use to absorb sunlight and produce sugars. While phytoplankton are often associated with harmful algal blooms, they are also the base of the marine food web, serving as food for fish and other sea creatures. Ocean regions with the highest concentrations of chlorophyll, or the greenest areas, were at higher latitudes, toward the poles. Mid-latitudes had relatively low levels of chlorophyll, or were more blue. The authors tracked global shifts in chlorophyll concentrations, a proxy for phytoplankton populations, over recent decades. The authors associated the poleward 'greening' with increasing sea-surface temperatures. 'This uneven distribution of chlorophyll (has been) intensifying over the past 20 years,' said lead author Haipeng Zhao, a postdoctoral researcher at the Georgia Institute of Technology. Zhao performed the research while at Duke University. The scientists quantified the trend using the Gini index, a measure typically used for studying wealth disparities. Kudela, of UC Santa Cruz, described the approach as 'a very elegant way' to address the question of whether ocean waters have been getting greener toward the poles. The new study analyzed open ocean waters; researchers didn't directly address coastal regions, like the Pacific Ocean waters offshore of California. Sediment in shallow coastal waters complicates satellite data: 'We don't think there's an effective algorithm that can accurately gather the phytoplankton concentrations in those coastal regions,' Zhao said. Coastal waters and the open ocean also experience distinct physical processes, Zhao explained. Kudela expects that the poleward shift in chlorophyll and phytoplankton described by the authors extends to the California coast, though the data could be noisier. Much of California lines up with latitudes associated with ocean waters that have gotten bluer over recent decades. Latitudes north of roughly Humboldt Bay have gotten greener. Scientists have already observed changes in marine environments: 'We're seeing organisms in California and Oregon and Washington moving northward because they're basically trying to follow their preferred temperature,' said Kudela, who authored a perspective accompanying the new study. Kudela noted in the perspective that the new results contrast with those of a 2023 study, which reported that oceans have become greener at low latitudes in recent decades and that the trend wasn't associated with sea-surface temperatures. That analysis, however, used a different type of satellite observation. El Niño conditions, associated with warmer-than-average sea surface temperatures, have provided short glimpses into what California waters could be like if global oceans warm, Kudela said. 'We oftentimes see the peak anchovy abundance shifts from Central California (and) Monterey up into Northern California,' Kudela said. Yellowfin tuna and dorado, normally found off Mexico, are more common off Southern California during El Niño years. The authors write that additional decades of satellite data are needed to determine whether poleward greening is a product of natural variability or driven by climate change.
France 24
15 hours ago
- Politics
- France 24
Trump 'Golden Dome' plan tricky and expensive: experts
Trump announced plans for the space-based system last month, saying it would eventually cost around $175 billion and would be operational by the end of his term in 2029. The planned defence shield's name is a nod to Israel's Iron Dome that has intercepted thousands of short-range rockets since 2011. But the US defence system would intercept much bigger intercontinental threats. The plan comes after a 2022 Department of defence study pointed to advances by China and Russia. Beijing is closing the gap with Washington when it comes to ballistic and hypersonic missile technology, while Moscow is modernising its intercontinental-range missile systems and developing advanced precision strike missiles, it said. Trump has claimed the "Golden Dome" will be "capable of intercepting missiles even if they are launched from other sides of the world". But analysts are sceptical. "I'm not holding my breath," said Thomas Withington, an associate fellow at the RUSI defence think tank. "The challenges are so significant at this stage that they may simply be unrealistic to surround in the timeframes that the Trump administration envisages." 'Poster child for waste' Thomas Roberts, of the Georgia Institute of Technology, said the "Golden Dome" plan was based on being able to detect when a long-range missile was fired. A missile's so-called "boost phase" -- which produces a heat blast that lasts one to two minutes and can be observed from space -- is the best time to deploy defences, he said. "If you had an enormous constellation of interceptors in orbit at all times, they could be readily de-orbited -- or systematically removed from orbit -- to strike an intercontinental ballistic missile," he said. But Todd Harrison, from the American Enterprise Institute, said this would require a massive number of satellites. "It takes about 950 interceptors spread out in orbit around the Earth to ensure that at least one is always in range to intercept a missile during its boost phase," he said. But that means that if an adversary launches a salvo of ten missiles, some 9,500 interceptors would be needed to ensure at least ten are within range. "Given that China has about 350 intercontinental ballistic missiles and Russia has 306 -- not including their sub-launched ballistic missiles -- scaling a space-based interceptor system to meet the threat quickly becomes impractical." The non-partisan US Congressional Budget Office estimates that, just to stop "one or two intercontinental ballistic missiles", the United States would need a constellation of satellites costing between $161 billion to $542 billion. The US military could spend billions of dollars on research only for the next administration to nix the project, Harrison warned. "Golden Dome could become the poster child for waste and inefficiency in defence," he said. The plan also calls for developing satellites able to fire lasers at missiles to avoid too much debris on impact. But a European defence contractor said on condition of anonymity that such lasers are "still beyond what even the Americans are capable of doing". "It's just an excellent way to give the US (defence) industry substantial funding so they can increase their technological lead without necessarily aiming for actual operational deployment," the contractor said. 'Global arms race'? Trump's plan is reminiscent of President Ronald Reagan ambition for a Strategic Defense Initiative in the 1980s, which also sought to place interceptor satellites in space. China and Russia, which both have nuclear weapons, have slammed the latest plan as "deeply destabilising". Nuclear-armed North Korea has called the plan a "very dangerous" threat. Julia Cournoyer, research associate at Chatham House, said the plan was risky as adversaries would likely see it "as an attempt to undermine the logic of nuclear deterrence". "If Washington is perceived to be developing a shield that could one day neutralise a retaliatory nuclear strike, it risks triggering a dangerous global arms race," which would exacerbate rather than reduce risk. Withington said Trump might be hoping to use the plan as leverage for talks with China and Russia. "It may be that the Trump administration is hoping that this would bring both countries to some kind of negotiating table to talk about a reduction of nuclear warhead sizes or to revitalise the arms control agenda," he said.
Int'l Business Times
15 hours ago
- Business
- Int'l Business Times
Trump 'Golden Dome' Plan Tricky And Expensive: Experts
President Donald Trump's proposed "Golden Dome" defence system is a plan that will face mammoth technical and financial hurdles, and could increase global insecurity, experts say. Trump announced plans for the space-based system last month, saying it would eventually cost around $175 billion and would be operational by the end of his term in 2029. The planned defence shield's name is a nod to Israel's Iron Dome that has intercepted thousands of short-range rockets since 2011. But the US defence system would intercept much bigger intercontinental threats. The plan comes after a 2022 Department of defence study pointed to advances by China and Russia. Beijing is closing the gap with Washington when it comes to ballistic and hypersonic missile technology, while Moscow is modernising its intercontinental-range missile systems and developing advanced precision strike missiles, it said. Trump has claimed the "Golden Dome" will be "capable of intercepting missiles even if they are launched from other sides of the world". But analysts are sceptical. "I'm not holding my breath," said Thomas Withington, an associate fellow at the RUSI defence think tank. "The challenges are so significant at this stage that they may simply be unrealistic to surround in the timeframes that the Trump administration envisages." Thomas Roberts, of the Georgia Institute of Technology, said the "Golden Dome" plan was based on being able to detect when a long-range missile was fired. A missile's so-called "boost phase" -- which produces a heat blast that lasts one to two minutes and can be observed from space -- is the best time to deploy defences, he said. "If you had an enormous constellation of interceptors in orbit at all times, they could be readily de-orbited -- or systematically removed from orbit -- to strike an intercontinental ballistic missile," he said. But Todd Harrison, from the American Enterprise Institute, said this would require a massive number of satellites. "It takes about 950 interceptors spread out in orbit around the Earth to ensure that at least one is always in range to intercept a missile during its boost phase," he said. But that means that if an adversary launches a salvo of ten missiles, some 9,500 interceptors would be needed to ensure at least ten are within range. "Given that China has about 350 intercontinental ballistic missiles and Russia has 306 -- not including their sub-launched ballistic missiles -- scaling a space-based interceptor system to meet the threat quickly becomes impractical." The non-partisan US Congressional Budget Office estimates that, just to stop "one or two intercontinental ballistic missiles", the United States would need a constellation of satellites costing between $161 billion to $542 billion. The US military could spend billions of dollars on research only for the next administration to nix the project, Harrison warned. "Golden Dome could become the poster child for waste and inefficiency in defence," he said. The plan also calls for developing satellites able to fire lasers at missiles to avoid too much debris on impact. But a European defence contractor said on condition of anonymity that such lasers are "still beyond what even the Americans are capable of doing". "It's just an excellent way to give the US (defence) industry substantial funding so they can increase their technological lead without necessarily aiming for actual operational deployment," the contractor said. Trump's plan is reminiscent of President Ronald Reagan ambition for a Strategic Defense Initiative in the 1980s, which also sought to place interceptor satellites in space. China and Russia, which both have nuclear weapons, have slammed the latest plan as "deeply destabilising". Nuclear-armed North Korea has called the plan a "very dangerous" threat. Julia Cournoyer, research associate at Chatham House, said the plan was risky as adversaries would likely see it "as an attempt to undermine the logic of nuclear deterrence". "If Washington is perceived to be developing a shield that could one day neutralise a retaliatory nuclear strike, it risks triggering a dangerous global arms race," which would exacerbate rather than reduce risk. Withington said Trump might be hoping to use the plan as leverage for talks with China and Russia. "It may be that the Trump administration is hoping that this would bring both countries to some kind of negotiating table to talk about a reduction of nuclear warhead sizes or to revitalise the arms control agenda," he said.
Los Angeles Times
a day ago
- Science
- Los Angeles Times
Efforts to reduce dust from dry Owens Lake bed are helping, report finds
The dry bed of Owens Lake has long been a major source of dust in the Owens Valley, but mitigation efforts have reduced those emissions to a point that other dust sources in the surrounding desert now cause most of the poor air quality days in the area, according to a new report. Owens Lake was left desiccated after Los Angeles began tapping the eastern Sierra watershed for its own needs more than a century ago. But the amount of dust coming from the lake bed has been declining in recent years as the L.A. Department of Water and Power has taken mitigation measures such as spreading water on parts of the lake bed. 'This is a success story in process,' said Ted Russell, a professor of civil and environmental engineering at Georgia Institute of Technology and chair of the Owens Lake Scientific Advisory Panel. 'You want to be able to understand where these sources are, such that you can better control them.' The panel, which was established in 2018 by the National Academies of Sciences, Engineering, and Medicine, released its report this week detailing research and data on off-lake sources of dust — also known as PM10, particulate matter that measure 10 microns or smaller, and that penetrate into the lungs and can cause health problems. The team said in the report that significant dust sources in areas around the lake include land where floods have left deposits of sand and debris, the Keeler Dunes, the Olancha Dunes, alluvial fans and areas where soil has been disturbed for road infrastructure. The scientists said some of these areas are naturally sources of dust, while others are emitting more of it because of diversions of water or alterations of the landscape by people. Russell said research shows that the DWP's dust control efforts have been successful in reducing PM10 emissions from the lake bed, as well as the frequency of exceedances of air quality standards. The DWP has invested about $2.5 billion in dust mitigation projects on the dry lake bed, using methods including the shallow flooding of the lake bottom, placement of gravel, tillage that roughens the soil and the planting of vegetation that serves as a windbreak. The days with air quality exceedances caused by sources other than the lake have gone up and down in recent years, without a clear trend, Russell said. 'Off-lake sources in this arid environment are significant and are driving a large number of the PM10 exceedances at this time,' Russell said. He said that means bringing the area into attainment with national air quality standards will require additional effects to control the dust sources other than the lakebed. The report was sponsored by the DWP and the Great Basin Unified Air Pollution Control District, which regulates air pollution in an area of about 32,000 people. The DWP had no immediate comment on the panel's findings. The scientists noted that on the northeastern side of Owens Lake, the Keeler Dunes transitioned during the last century from a 'largely vegetated dune system' to one that releases more dust. They wrote that 'increased sand transport following the diversion of water from Owens Lake destabilized the Keeler Dunes.' The scientists said ongoing efforts to stabilize the Keeler Dunes have been effective in mitigating dust. The work there has included arranging bales of straw on the sand, which has enabled native shrubs to take root and begin to keep down the blowing dust. The panel said these and other efforts to establish native vegetation hold promise to control dust in other areas and further improve air quality in the Owens Valley.
