Latest news with #DominikSchmitt
Yahoo
04-04-2025
- Science
- Yahoo
Something Truly Scary Discovered at The Bottom of Belize's Great Blue Hole
An expedition to the bottom of the Great Blue Hole off the coast of Belize in Central America has returned with a cargo of worrying information. After studying a 30-meter (98-foot) sediment core extracted from the floor of the sinkhole, scientists discovered that tropical cyclones have increased in frequency over the last 5,700 years. This trend is not only going to continue – it's going to reach a fever pitch driven by a changing climate. "A total of 694 event layers were identified. They display a distinct regional trend of increasing storminess in the southwestern Caribbean, which follows an orbitally driven shift in the Intertropical Convergence Zone," writes a team led by geoscientist Dominik Schmitt of Goethe University Frankfurt in Germany. "A 21st-century extrapolation suggests an unprecedented increase in tropical cyclone frequency, attributable to the Industrial Age warming." The Great Blue Hole at Belize is a popular destination for scuba divers, popularized by oceanographer Jacques Cousteau more than 50 years ago. At a depth of 124 meters, it plunges into the surrounding seafloor, its upper reaches a haven for marine life seeking protection from the wild vagaries of ocean weather. There's another facet to this relative coziness; any sediment dumped within is likely to stay put. Layers of mineral deposited in sequence on the sinkhole floor serve as an excellent record of times past, recording major events like cyclones that churn up and dump new material into the Great Blue Hole. "Due to the unique environmental conditions – including oxygen-free bottom water and several stratified water layers – fine marine sediments could settle largely undisturbed in the Great Blue Hole," Schmitt explains. "Inside the sediment core, they look a bit like tree rings, with the annual layers alternating in color between gray-green and light green depending on organic content." The extraction of a core sample is a delicate procedure that involves drilling into the seafloor and carefully removing a long, vertical, cylindrical section. An analysis of that sediment involves identifying which layers were deposited by which processes. Violent events such as cyclones deposit layers with larger sediment grains than non-storm ocean processes, so it's a matter of carefully combing over the core and identifying those large-grained, differently-hued cyclone deposits. "The tempestites stand out from the fair-weather gray-green sediments in terms of grain size, composition, and color, which ranges from beige to white," Schmitt says. The Great Blue Hole of Belize started its life as a limestone cave underground, an origin alluded to by the huge stalactites that can still be found in its depths. It became a sinkhole during the last glacial period, when its roof collapsed, subsequently flooding the cavity with water and transforming it into the thriving marine ecosystem it is today. The team's work involved carefully studying a core that covered the most recent 5,700 years of that history. In that timespan, the researchers identified 694 "event layers" that they attributed to tropical cyclones. With this data in hand, they were then able to piece together how cyclone frequency has changed over time The core revealed a steady trend of increasing cyclone activity over the 5,700 years. "A key factor has been the southward shift of the equatorial low-pressure zone," Schmitt says. "Known as the Intertropical Convergence Zone, this zone influences the location of major storm formation areas in the Atlantic and determines how tropical storms and hurricanes move and where they make landfall in the Caribbean." But there were smaller-term fluctuations in cyclone frequency that, the researchers found, could be linked to warmer and cooler periods in Earth's climate timeline, with greater frequency occurring during warm periods. Based on these trends, we could be facing an unprecedented spike in tropical cyclone activity. There were nine cyclone events in the last 20 years alone; a frequency that is inconsistent with normal, natural climate fluctuations. "Our results suggest that some 45 tropical storms and hurricanes could pass over this region in our century alone," says biosedimentologist Eberhard Gischler of Goethe University Frankfurt. "This would far exceed the natural variability of the past millennia." The team's research has been published in Science Advances. 'Largest' Rare Earth Metals Deposit Discovered in Kazakhstan Oxygen Metabolism Emerged on Earth Before The Great Oxidation Event, Study Reveals Earth's Crust Is Dripping Under Midwest US, Scientists Discover
Yahoo
02-04-2025
- Science
- Yahoo
Scientists drilled into Belize's Great Blue Hole and discovered a worrying trend
When you buy through links on our articles, Future and its syndication partners may earn a commission. Tropical cyclones in the Caribbean are getting more frequent — and could increase significantly in the coming decades, evidence found buried deep within the Great Blue Hole suggests. Researchers took a sediment core from the Great Blue Hole sinkhole, situated about 50 miles (80 kilometers) off the coast of Belize, which revealed that tropical cyclones have increased in frequency over the past 5,700 years. The scientists described their findings in a study published March 14 in the journal Geology. "A key finding of our study is that the regional storm frequency has increased continuously since 5,700 years B.P. (before present)," study lead author Dominik Schmitt, a researcher at Goethe University Frankfurt's Biosedimentology Research Group, told Live Science. "Remarkably, the frequency of storm landfalls in the study area has been much higher in the last two decades than in the last six millennia — a clear indication of the influence of Modern Global Warming." Tropical cyclones are intense, rotating, low-pressure systems that form over warm ocean waters. They transfer heat from the ocean into the upper atmosphere. Tropical cyclones can be extremely destructive, producing strong winds, heavy rainfall and storm surges. To learn more about these storms over a long period of time, the researchers extracted the sediment core from the bottom of the 410-foot-deep (125 meters) Great Blue Hole — a massive underwater sinkhole that formed as sea levels rose during the last ice age, around 10,000 years ago. This sediment core, measuring 98 feet (30 m) long, is the longest continuous record of tropical storms in the area. By analyzing the layers of sediment in the core, the scientists could determine the number of tropical cyclones that had occurred over the past 5,700 years. Two layers of fair-weather sediment are usually laid down every year, enabling the researchers to count back the years like the rings of a tree and compare when storm-event sediment layers were deposited. The researchers found that tropical cyclones have been getting more frequent over the past 5,700 years, with a particular increase in frequency since we started burning fossil fuels during the Industrial Revolution. "Over the past six millennia, between four and sixteen tropical storms and hurricanes have passed over the Great Blue Hole every century," Schmitt said. In the past 20 years alone, however, the researchers found evidence of nine tropical storms passing over the same region. There appear to be two factors driving the rise in tropical cyclones, the researchers noted. Much of the frequency increases over the past few thousand years may be due to a southward migration of the Intertropical Convergence Zone (ITCZ). The ITCZ is a region near the equator where the trade winds of the Northern and Southern hemispheres come together, resulting in low atmospheric pressure, high humidity and frequent thunderstorms. Along the northern edge of the ITCZ is the Hurricane Main Development Region (MDR), where most tropical cyclones in the Atlantic form. The ITCZ usually moves northward in the summer and southward in the winter as a result of changing sea surface temperatures, but it has also been steadily moving southward over the past few thousand years. This southward migration of the ITCZ "has probably led to a southward displacement of the major Atlantic storm genesis region, and a shift of the main storm trajectories from formerly higher to now lower latitudes," Schmitt explained. Increases in global sea surface temperatures as a result of human-caused climate change are likely responsible for the recent spike in tropical storms, and will likely result in even more frequent tropical cyclones in the coming decades, according to the study. "The nine modern storm layers from the last 20 years indicate that extreme weather events in this region will become much more frequent in the 21st century," Schmitt said. The researchers predict that as many as 45 tropical storms and hurricanes could hit the Caribbean before the end of 2100. RELATED STORIES —Deepest blue hole in the world discovered, with hidden caves and tunnels believed to be inside —'More people are in harm's way': Tornadoes are shifting east of Tornado Alley, forecasters warn —Giant, near-perfect cloud ring appears in the middle of the Pacific Ocean — Earth from space "This high number is far in excess of what has been the case in the past 5,700 years," Schmitt said. "An explanation for this high storm frequency is not the natural variations in climate or solar radiation, but the progressive global warming during the Industrial Age, accompanied by fast rising sea-surface temperatures and stronger global La Niña events, which create optimal conditions for the development and rapid intensification of storms."
