This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A new study led by the Woods Hole Oceanographic Institution (WHOI) provides the most comprehensive observational analysis yet of the towering ice cliffs that fringe Earth's ice sheets, giving scientists new evidence to evaluate a long-debated process that could influence future sea level rise. Improving these projections is increasingly important as rising seas threaten coastal communities and infrastructure worldwide.
Marine ice-cliff instability (MICI) is a theory that proposes extremely tall ice cliffs, taller than about 100 meters (328 feet) above the waterline, can become structurally unstable and trigger a cycle of rapid, self-sustaining ice loss. Because that process has never been directly observed, scientists have debated whether it should be included in projections of future sea level rise. To test the theory against real-world observations, researchers analyzed the characteristics of ice cliffs using 15,330 individual satellite observations collected around the margins of Earth's ice sheets.
The study, published in Science, utilized satellite laser altimetry, a technique that measures surface elevation by timing how long it takes laser pulses to travel from a satellite to Earth's surface and back. Those measurements allowed the researchers to calculate cliff heights and compare them with ice thickness, water depth, crevassing and calving rates across thousands of locations around the ice sheets. "Our findings suggest ice-sheet models may underestimate how quickly tall ice cliffs can break apart.
At the same time, the observations show that glaciers often thin and retreat into regions where the conditions become less favorable for continued rapid retreat," said Caroline Needell, an MIT-WHOI Joint Program doctoral student and lead author of the study. "These findings show that some of the processes described by marine ice-cliff instability occur in nature, but they also show that other factors can limit rapid retreat." Global sea level has already risen by more than 8 inches (20 centimeters) since 1880, and scientists project it will continue to rise throughout this century as ice sheets lose mass. By identifying the conditions that drive and limit rapid ice-cliff retreat, the study helps scientists improve models of how ice sheets contribute to future sea level rise.
More accurate projections are increasingly important for coastal communities, where rising sea levels can worsen flooding, accelerate erosion, damage infrastructure and intensify storm-surge impacts. "Understanding how ice sheets lose mass is key to improving projections of future sea level rise," said Catherine Walker, a glaciologist at WHOI and author of the study. "To make better predictions, we need observations that show how glaciers behave where they meet the ocean and help us improve the models we use to understand future change." Unlike previous studies that focused on individual glaciers or computer simulations, this work examines thousands of ice cliffs across Earth's ice sheets using a consistent set of satellite observations.
The data set gives scientists a way to test ice-sheet models against real-world measurements, helping improve predictions of how glaciers may respond as the climate changes. Discover the latest in science, tech, and space with over 100,000 subscribers who rely on Phys.org for daily insights. d research that matter—daily or weekly. "When ice sheets start to calve, they can do so very rapidly," said Jeremy Bassis, a geophysicist at the University of Michigan and author of the study.
Extract — continue reading at the source.
