Melting on the Antarctic Ice Sheet for the 2024 to 2025 season began with above average melt extents in all regions, but melt extent dropped to nearly zero or below average from February 1 to March 15. Net accumulation of snow, part of the ice sheet’s surface mass balance, was far above average for the year ending in February 2025. Thus, extensive snowfall helped reduce the ice sheet’s net contribution to sea level rise for this period.
Current conditionsAfter setting records in December and January for melt extent in the 47-year satellite record, melt extents dropped abruptly by early February when conditions over the Antarctic Peninsula cooled. Overall, the number of melt days exceeded the 1991 to 2020 long-term average by approximately 10 days in the Larsen C Ice Shelf area, 15 days in the Fimbul Ice Shelf area, and over 30 days along the eastern side of the Amery Ice Shelf. Also notable were above average melt days in the West, Shackleton, and Totten Ice Shelf areas. The Sulzberger and Ross Ice Shelves were among the few areas with below average melt days for the austral summer season. Extensive ponding apparent in January in satellite images on the Larsen B remnant, known as Scar Inlet Ice Shelf, and northern Larsen C, all refroze in February; however, ponding and some surface melt flow were still visible on the Amery and Roi Baudouin Ice Shelves into March, although with a frozen surface at that point.
Ice sheet losses this year
Total net accumulation of snow, known as the surface mass balance (SMB), has been far above average for the March 2024 to February 2025 period, by nearly 200 billion tons. SMB is the net contribution of snowfall, and a tiny amount of rainfall, minus the evaporation of snow and ice from the surface. The excess snowfall was primarily located along the Dronning Maud Land coast, central East Antarctica, and the Getz Ice Shelf area of West Antarctica. For reference, the average annual total surface mass balance for the continent is roughly 2,400 billion tons.
No surprises, the warmer ocean is bringing more snow to the edge of the continent.
Then with this we also had record surface melt:
The Great Un-Freezing: Record Antarctic surface melt extent set; Peninsula melting slows
THURSDAY, JANUARY 30, 2025
Surface melting for the Antarctic ice sheet appears to have set a record for the 46-year satellite observation period on January 2, 2025. All areas of the Antarctic coast that generally see significant summertime melting continue to accumulate melt days at a faster-than-average pace, except along the northern West Antarctic ice shelves, which are now near-average.
Conditions in context
The persistently high melt extents for much of December and January this season are due to widespread above-average air temperatures across the continent. However, warmth over the Peninsula has been less extreme and air temperatures have been near-average over portions of the Wilkes Land coast. Air circulation patterns explain some of the warmest regions (e.g., to the southeast of low-pressure areas, or southwest of high-pressure regions), but in general are atypical of the continent.
The balance between these two positive and negative feedbacks will oscillate as warming continues but melting will inevitably win in the end..
