The existing C3S seasonal predictions of Arctic sea ice concentration only provide monthly means and no regional assessments. For marine users who have to operate in the vicinity of the ice edge, more fine-grained assessments of the forecasts are needed to be useful. This is what ACCIBERG’s ICECAP software has been developed to do, as a contribution to the evolution of the Copernicus Services, in order to bring sea ice forecasts closer to the users.
For this year’s summer minimum, near-average conditions are expected. Forecasts from July onwards have been indicating slightly more favourable conditions in the northern sea route than in recent years, but still no navigation possible after October. The conditions on the Northwest passage route are heavier than in the past years.
Left: forecast of pan-Arctic sea ice extent; thin lines are ensemble members, indicating the forecast uncertainty, and the thick line is the ensemble mean forecast. Right: ensemble-mean forecast of sea ice concentration at the predicted minimum on 20th September 2026.
As a demonstration of what is possible using ICECAP, Figure 2 shows the daily evolution of pan-Arctic sea ice extent and a map of the ice cover expected around this year’s annual minimum as predicted by the ECMWF contribution to the C3S multi-model seasonal forecasting system. On the left, we see that the annual minimum is expected around the 20th September, but there is uncertainty about the minimum extent. On the right, we see there seems to be a good chance for the ice to retreat sufficiently in the Laptev and East Siberian Seas to allow shipping. However, there are still heavy ice conditions in the Northwest passage. Users of ICECAP will notice that both the amplitude and the timing of the sea ice minimum change from one model to another, suggesting that there is substantial uncertainty in the forecasts.
The ICECAP software, now runs as a prototype service on the EDITO platform and allows end users to visualize sea ice forecasts from C3S and CMEMS services at the touch of a button.
