The rate of glacier ice flow is more sensitive to stress than previously computed, according to a new study by MIT scientists that overthrows a years old formula used to explain ice circulation. Thick glacier ice streams “really likewise to honey,” explains Joanna Millstein, a PhD student in the Glacier Dynamics and Remote Sensing Group and lead author of the research study. Thick glacier ice flows “really likewise to honey,” describes Millstein. Other parts of the flow law formula represent distinctions in temperature level, ice grain size and orientation, and impurities and water consisted of in the ice– all of which can change circulation velocity. Factors like temperature might be especially crucial in understanding how ice circulation effects sea level increase in the future, Millstein states.
The rate of glacier ice circulation is more conscious stress than formerly computed, according to a new study by MIT researchers that overthrows a decades old formula utilized to describe ice circulation. Pictured is the Juneau ice field in Alaska. Credit: Joanna Millstein
Modifications to a crucial ice circulation formula might refine quotes of water level increase.
The rate of glacier ice flow is more conscious stress than previously calculated, according to a brand-new study by MIT scientists that upends a decades-old equation utilized to explain ice flow.
Tension in this case refers to the forces acting upon Antarctic glaciers, which are mainly influenced by gravity that drags the ice down towards lower elevations. Viscous glacier ice flows “really likewise to honey,” describes Joanna Millstein, a PhD student in the Glacier Dynamics and Remote Sensing Group and lead author of the research study. “If you squeeze honey in the center of a piece of toast, and it piles up there prior to exuding outward, thats the specific same movement thats occurring for ice.”
The modification to the equation proposed by Millstein and her coworkers ought to enhance designs for making forecasts about the ice flow of glaciers. This could help glaciologists predict how Antarctic ice flow might add to future water level increase, although Millstein said the formula modification is unlikely to raise price quotes of sea level increase beyond the maximum levels currently forecasted under climate change models.
Joanna Millstein, envisioned here in Western Greenland. Viscous glacier ice flows “actually similarly to honey,” describes Millstein. Credit: Robert Hawley
” Almost all our uncertainties about water level rise originating from Antarctica relate to the physics of ice circulation, though, so this will ideally be a restraint on that uncertainty,” she states.
Other authors on the paper, released in Nature Communications Earth and Environment, include Brent Minchew, the Cecil and Ida Green Career Development Professor in MITs Department of Earth, Atmospheric, and Planetary Sciences, and Samuel Pegler, a university academic fellow at the University of Leeds.
Benefits of huge data
The equation in question, called Glens Flow Law, is the most extensively used formula to explain thick ice flow. It was developed in 1958 by British scientist J.W. Glen, one of the couple of glaciologists working on the physics of ice circulation in the 1950s, according to Millstein
With fairly couple of scientists operating in the field till recently, in addition to the remoteness and inaccessibility of most big glacier ice sheets, there were couple of attempts to adjust Glens Flow Law outside the lab till recently. In the recent study, Millstein and her associates benefited from a brand-new wealth of satellite imagery over Antarctic ice shelves, the floating extensions of the continents ice sheet, to modify the stress exponent of the circulation law.
Pictured is the Juneau ice field in Alaska. Credit: Joanna Millstein.
” In 2002, this significant ice rack [Larsen B] collapsed in Antarctica, and all we have from that collapse is 2 satellite images that are a month apart,” she says. “Now, over that exact same location we can get [imagery] every 6 days.” The new analysis reveals that “the ice flow in the most vibrant, fastest-changing regions of Antarctica– the ice shelves, which basically hold back and hug the interior of the continental ice– is more conscious tension than frequently assumed,” Millstein says. Shes optimistic that the growing record of satellite data will assist catch fast changes on Antarctica in the future, offering insights into the underlying physical procedures of glaciers.
However tension isnt the only thing that affects ice circulation, the scientists keep in mind. Other parts of the flow law formula represent differences in temperature level, ice grain size and orientation, and impurities and water included in the ice– all of which can alter flow speed. Factors like temperature level might be particularly crucial in understanding how ice circulation effects water level rise in the future, Millstein states.
Cracking under stress
Millstein and associates are likewise studying the mechanics of ice sheet collapse, which involves various physical models than those utilized to understand the ice circulation problem. “The breaking and splitting of ice is what were dealing with now, utilizing strain rate observations,” Millstein says.
The scientists use InSAR, radar images of the Earths surface area gathered by satellites, to observe deformations of the ice sheets that can be utilized to make accurate measurements of stress. By observing locations of ice with high stress rates, they want to much better comprehend the rate at which crevasses and rifts propagate to trigger collapse.
Recommendation: “Ice viscosity is more conscious tension than commonly presumed” by Joanna D. Millstein, Brent M. Minchew and Samuel S. Pegler, 10 March 2022, Nature Communications Earth and Environment.DOI: 10.1038/ s43247-022-00385-x.
The research study was supported by the National Science Foundation.