Polar sea ice is a dynamic, ever-changing system that holds the key to understanding global climate patterns. In a groundbreaking collaboration, mathematicians and climate researchers from the University of Utah have developed new models to unravel the complexities of this vital component of our planet. Their findings shed light on the crucial processes that drive sea ice behavior and its far-reaching impact on the world. Sea ice is not just a frozen layer, but an intricate network of water, ice, and air pockets that interacts with the ocean and atmosphere in profound ways.
Mapping the Marginal Ice Zone
An innovative study about the Arctic’s marginal ice zone (MIZ) has been undertaken by atmospheric sciences professor Court Strong. The wavy ice edge between the dense pack ice bloom and the open ocean above it has increased by an incredible 40% in the last 40 or so years. With the help of satellite imagery, Strong and his team have learned that it can be understood as a large-scale “phase transition” akin to ice thawing into water.
Melting, however, has generally been considered a relatively local phenomenon, while under the new view, the MIZ represents an extensive zone of transition to regions where both ice and water are present. Understanding this point not only addresses the ‘soggy’ aspect of the MIZ but also helps explain why it is very dynamic, varying with the seasons and as subsea earthquakes rapidly warm some regions of seawater.
Unraveling the Thermal Secrets of Sea Ice
In a separate study led by former University of Utah postdoctoral researcher Noa Kraitzman, the team explored what was happening on a microscale in sea ice. Sea ice is not a dense mono-particle phase as imagines but rather consists of numerous small brine inclusions within a porous structure. The presence of these inclusions permits water flow, which strongly affects the velocity heat can be transferred within ice.
With fine-tuned math, however, the researchers could calculate just how much this water flow amps up heat being carried through the ice. This discovery hints that the prevailing computer models of the climate might be lowballing how much heat is moving through the sea ice, in part because they don’t take this kind of convection fully into account. Enhanced models like these can enable scientists to make more accurate predictions of how quickly the sea ice will melt and how this thawing ice will impact the climate around the world.
The Synergy of Mathematics and Climate Science
This theme of applying well-respected mathematical rigor to the thorny problems faced when we look at sea ice and try to make sense of all phenomena on all scales is consistent between the two demonstrations. The researcher Ken Golden, who has long been considered an expert on sea ice as a lead developer for Navier-Stokes solvers with the Energy Department’s Los Alamos National Laboratory, described: “The ice is not a continuum. Like sea ice, it is a composite material that has small brine inclusions. In other words, the very same physics and math can be used in different situations to arrive at the macroscopic effective thermal properties.
The melding of these two worlds – mathematicians with their general theories for complex systems, and climate scientists with data from the real world — provides a key blueprint for future work that has the potential to critically reassess our knowledge about the Arctic and its impact on global climate. More work is, of course, required to further develop and sharpen these models — helping scientists more accurately forecast what the future of polar sea ice may be in a changing climate and its impacts cascading into society, empowering policymakers and the public about how immediate action on a rapidly warming world lies.
