Greenland Ice Sheet

The Greenland Ice Sheet contains enough ice to raise the world’s oceans by 24 feet. It’s current contribution is less than a mm per year but it adds up and it doesn’t go away but, melt increases nonlinearly with warming and importantly, there will come a time when melt becomes so extreme that warming will create a perpetual and extreme melt feedback that is irreversible. The challenge then is to restore our climate to prevent this runaway feedback from occurring. It will take time to restore our climate, but because even current warming means Greenland continues to melt and proceed towards the point of no return, there is no negotiation about the mandate to restore our climate back to within the evolution ary boundaries of the Greenland Ice sheet at less than the natural maximum temperature of our old climate at about 1 degree C warming above normal.  the 1.5 degree C warming target of our climate culture then is too warm to prevent irreversible collapse and 24 feet of sea level rise.

The Greenland Ice Sheet has seen a net loss of ice every year since 1998 or for 27 years in a row. Only ocean water expansion from warming creates more sea level rise than Greenland melt.

Greenland Ice Sheet Ice Loss

Greenland is losing ice about seven times faster than it was 30 years ago. This video is of an underice river draining the ice sheet, 18 miles from Kangerlussuaq down the longest road in Greenland near the Arctic Circle. The black color is dust and ground bedrock entrained in the basal flow of ice. The water mostly comes from surface melt that drains to the bottom of the ice sheet through creveasses and moulins (drain holes in the ice sheet). This melt water also serves to lubricate the flow ice ice from the interior, speeding its flow outward from farther inland.

Greenland Ice Sheet – Albedo Feedback

Wherle, Box et al., published albedoi data for their study sites in Wets greenland in 2021. they found that melt season ice albedo was 79% precent reflective before all the previous season’s snow melted away. Reflectivity steadily decreased because of snow wetting and appearance of bare-ice patches of old ice where dust has accumulated in previous melt years. Once bare ice was completely revealed, albedo decreased to 56%. After about a week, albedo began to decrease again for about another 10 days when it reaches a low reflectivity of 45%. this second fall in albedo is attributed to algal growth that darkens the bare-ice surface.

Algae image composite from Stibal, box et al., 2017. (a) The principal study site. (b) The ice sheet surface showing highly pigmented surface blooms. Photomicrographs of cells of the filamentous alga Ancylonema nordenskiöldii in various stages of (c) cell elongation and cell division, (d) terminal cell of a filament of A. nordenskiöldii alongside a much larger cell of Cylindrocystis sp., and (e) alga and a mineral particle. Scale bars represent 20 μm.

Albedo monitoring station from Wehrle, Box, et al., 2021. 1: solar and infrared radiation, 2: tilt sensor, 3: satellite antenna, 4: wind speed & direction, 5: snow/ice surface height, 6: air temperature & humidity, 7: ice ablation hose, 8: solar panel, 9: datalogger, barometer and GPS, 10: battery, 11: ice temperature profile (8 levels)

Greenland Ice Sheet Discharge Streams

This time lapse was taken by ice scientist David Holland of New York University, from the balcony of the Hotel Hvide Falk in Ilulissat, Greenland. What is shown is the iceberg discharge from the Sermeq Kujalleq (ilulissat Glacier), that flows 10 percent of Greenland Ice Sheet’s discharge – the most of any in Greenland. The icefjord was designated a World Heritage Site in 2004, is 3 to 5 miles wide and 34 miles long extending to the edge of ice sheet from Disko Bay of Baffin Bay, on the western side of Greenland at the Arctic Circle. It’s discharge is about 70 gigatons of ice and meltwater annually, as determined by observations of ice discharge flow and instrumented seals traversing beneath the ice discharge stream before it grounds in bedrock about 6 miles inland from the calving face of Sermeq Kujalleq.

Antarctic Sea Ice Decline

Antarctica’s sea ice was not supposed to decline until the later half of the 21st century, but in 2015, a stark and decisive downturn in sea ice area began. There are several reasons why Antarctic sea ice was not supposed to decline for generations yet. Warming increases wind strength and Antarctica is no exception. Because the predominant wind there is off of land, stronger winds blow sea ice farther out to sea leaving open that freezes, creating an ice machine of sorts that increases the area covered by sea ice. More sea ice means more salt water brine is expelled from the ice that because of its density, sinks into the deep ocean. Seasonal melt increases the freshness of the surface waters, strengthening the halocline where different salt densities of water do not mix well. This freshening of surface waters that includes melt from increased iceberg discharge, allows more ice to form faster. Then there is the disruption of ocean currents around Antarctica that is plausibly breaking down the halocline and making surface waters saltier and harder to freeze.

Southern Ocean Changes – “Marked” and “Dramatic”

Antarctic sea ice coverage has taken a “markedly” strong, and “dramatic” downturn in coverage as the authors  of Silvano 2025 say, plausibly indicating a new state of Southern ocean currents is developing that significantly amplifies global warming with feedback effects to Antarctic sea ice and the Antarctic Ice Sheet. This is happening while Antarctic sea ice extents is at a new record low.

Antarctic Ice Sheet Discharge

Between 1979 and 2023, the Antarctic Ice Sheet lost on average 107 Gt of ice per year, contributing a total of 13.4 mm to sea level rise. as recently as the 2007 IPCC report, Antarctica was not supposed to begin losing ice until after the turn of the 22nd century. It is now becoming apparent that Antarctica’s ice sheets are degrading, at least in the west, where this collapse would likely trigger collapse of the Eastern Antarctic Ice Sheet.

Abram 2025 says “evidence is emerging for rapid, interacting and sometimes self-perpetuating changes in the Antarctic environment.” The abrupt warming of the southern ocean spells increased discharge of ice streams from underice melt feedbacks with the tipping point for Antarctic ice sheet discharge being exceeded even with the best IPCC scenarios of 1.5C warming. Amplifying feedbacks are common in Antarctica, with anticipated enhancement of other Earth systems degradation leading to plausible systems collapses cascades. global cascades.

Rignot 2024 says unforseen excursion of seawater beneath the supposed “grounding line” of the Thwaites Glacier (with deep connections to the stability of the East Antarctic Ice Sheet, is happening because of tidal action for  many kilometers beyond where the grounding line was supposed to be, and during spring tides for many kilometers further. This behavior is not in modeling with implications for faster discharge and collapse than suggested by current science.