Qurexa Logo
Qurexa

Trust. Care. Deliver.

Back to Blog & Insights
Lifestyle

Why Arctic sea ice moves so strangely: it is bumper cars

Qurexa Editorial Team19 September 20267 min read 0 0
Why Arctic sea ice moves so strangely: it is bumper cars

What happened

Engineers have worked out why Arctic sea ice drifts in a way that has long puzzled scientists, and the explanation turns out to be simpler than expected. The answer is that the ice bumps into itself. The study was led by the University of California, Riverside and published in the journal Physical Review Letters in September 2026. It was led by Bryan Shaddy, who did the work as an undergraduate at UC Riverside and is now at the University of Southern California, with UCR materials scientist Alex Greaney and Bhargav Rallabandi, associate professor of mechanical engineering. Arctic sea ice is not one solid sheet. Much of it is broken into separate pieces, called floes, which range from small fragments to slabs several miles across. Wind pushes these floes around. The puzzle was that the ice does not spread out in the way simple models predicted. Its movement showed statistical patterns that did not match what you would expect if each floe simply responded to the wind on its own. The researchers modelled the ice as a granular medium. That means treating it like a collection of loose solid pieces, in the way you might model sand or gravel, rather than as a continuous sheet. They then applied realistic, randomly varying winds. The key insight is what happens at each collision. When one floe hits another, some of the energy the wind supplied is lost, and the floe's free run is cut short. It cannot keep accelerating, because it keeps hitting its neighbours. Using only directly measured local conditions as inputs, the model reproduced how real ice behaves in the Fram Strait, off Greenland, including its spread, its range of speeds and its statistical patterns.

Why this matters

Knowing where sea ice will go is a practical question, not only an academic one. Shipping is the most obvious case. As Arctic ice retreats, more vessels are using northern routes, and knowing where ice will drift is a safety matter. Ice that moves unexpectedly into a shipping lane is a hazard, and forecasts that are wrong by a day or a few miles have consequences. It matters for communities too. People living in Arctic coastal regions depend on ice conditions for travel, hunting and fishing, and for protecting shorelines from storm waves. Ice that arrives late or leaves early changes daily life. It also matters for climate models. Sea ice is bright and reflects sunlight back into space. Open water is dark and absorbs it. How much of the Arctic is covered by ice, and how that ice is distributed, affects how much heat the region takes in. Getting ice movement right makes climate projections better. The broader point is about the type of explanation found. The researchers did not need to add complicated new physics. They needed to stop treating the ice as a smooth continuous sheet and start treating it as a crowd of objects bumping into each other. That kind of shift, from continuous to granular, has proved useful in other fields, from modelling grain flowing in silos to understanding how crowds of people move. It is satisfying when the same idea explains something as large as the Arctic.

What the evidence actually says

The evidence here is reasonably strong, and it is worth being clear about why. The convincing part is that the model reproduced several different measured properties at once, using only directly measured local environmental and ice conditions as inputs. It matched the dispersion of the ice, the distribution of velocities and the power spectrum of its motion in the Fram Strait. That last point matters more than it sounds. A model with enough adjustable settings can usually be tuned to match one observation. Matching several independent statistical properties simultaneously, without tuning the inputs to fit, is a much better sign that the underlying mechanism is right. There are limits, though. This is a simulation compared against observations, not a direct measurement of floes colliding. The researchers did not watch individual collisions and measure the energy lost in each one. They showed that a model built on that assumption produces what is actually seen. That is good evidence, but it is indirect. The validation focused on the Fram Strait, which is one region, and a well-studied one. The Fram Strait is where a large volume of ice exits the Arctic, so it is an important place, but it is not the whole Arctic. Whether the model performs as well elsewhere, particularly in regions with different ice concentrations, is a question for further work. The researchers also note that how often collisions occur depends on how much ocean is covered by ice and on floe size. That is a sensible conclusion, and it carries an implication worth noting. As the Arctic warms and ice breaks into smaller pieces spread more thinly, the collision behaviour itself will change. A model validated against today's conditions may need rechecking against tomorrow's. Finally, this is a study about physics, not a study about climate change. It does not make any new claim about how fast the Arctic is warming or how much ice will be lost. It provides a tool that could make such predictions more accurate.

Practical advice

This is one of those findings with no direct action attached, so the honest advice is about how to follow it rather than what to do. If Arctic conditions interest you, the US National Snow and Ice Data Center publishes free monthly updates on sea ice extent, with maps and clear explanations. The UK's Met Office and the British Antarctic Survey also publish accessible material on polar science. If you are reading about Arctic ice generally, one distinction is worth holding on to, because it is the source of a great deal of confusion. Sea ice extent, meaning how much ocean is covered, and sea ice volume, meaning how much ice there actually is, are different measurements and can move in different directions in a given year. Headlines often use them interchangeably. Volume is generally the more meaningful of the two for long-term trends. Another useful habit: be wary of any single year's figures being presented as a trend. Sea ice varies considerably from year to year for reasons including wind patterns. Trends in this field are measured over decades. For anyone with a young person interested in science or engineering, there is a detail in this story worth mentioning. The study was led by someone who began the work as an undergraduate. Meaningful published research is not exclusively the work of senior professors, and undergraduate research opportunities exist at many universities.

What to know

Engineers at the University of California, Riverside have found that collisions between individual ice floes explain the unusual way Arctic sea ice moves. Each collision dissipates energy supplied by the wind and shortens how far a floe can travel freely, which limits how the ice spreads. The team modelled sea ice as a granular medium responding to randomly varying winds. Using only directly measured local conditions, the model reproduced the dispersion, velocity distribution and power spectrum of real ice observed in the Fram Strait. The work was published in Physical Review Letters in September 2026, led by Bryan Shaddy with Alex Greaney and Bhargav Rallabandi. Better predictions of ice movement matter for shipping safety, Arctic communities and climate models. The study validated its model in one region, and collision behaviour depends on ice coverage and floe size, both of which are changing as the Arctic warms. It makes no new claim about the pace of warming itself. Sources: Physical Review Letters, "Anomalous Statistics of Sea Ice Transport are Explained by Collisional Rules", September 2026, https://journals.aps.org/prl/abstract/10.1103/g8y2-8ytt ; UC Riverside News, "Engineers solve puzzle of Arctic sea ice movement", 16 September 2026, https://news.ucr.edu/articles/2026/09/16/engineers-solve-puzzle-arctic-sea-ice-movement ; Phys.org, "Engineers solve puzzle of Arctic sea ice movement", September 2026, https://phys.org/news/2026-09-puzzle-arctic-sea-ice-movement.html This article is for general information and is not medical advice. If anything here relates to your health or your care, speak to a doctor, pharmacist or other qualified healthcare professional.

#Arctic#sea ice#climate#physics#oceans#research

Related articles