As summer begins in the southern hemisphere, global warming has melted enormous swathes of Antarctic sea ice. The lowest extent of sea ice ever observed by satellite just a day or so ago.
The Amundsen Sea Embayment is about the size of Texas, and the ice is approximately two miles thick. The ASE is one of three ice drainage basins in West Antarctica. It includes the ice of Pine Island Glacier, Ninnis, the remaining portion of the Thwaites glacier’s tongue, and the land ice behind it. The flow of glaciers to the sea in the embankment has been accelerating significantly since the turn of the century. Snowfall adds volume to the ice streams and has not changed at all.
The central tongue of Thwaites Glacier formed a dramatic rift in 2001, and in 2002 broke away from the main glacier, became stuck on a sea mount, and stayed there until NASA Worldview imagery showed the iceberg named B22 freed itself this month and now floating quickly to the open sea. The development is critical news as Thwaites is now exposed to stormy southern ocean wave action that will repeatedly lift and pound the vulnerable and retreating shelf coined as the doomsday glacier due to its potential for planetary coastal destruction. The collapse of Thwaites and possibly the entirety of the Amundsen Sea Embayment’s land ice to flow into the ocean would raise sea levels worldwide by just over four feet.
If you are wondering if this news has made headlines yet, it hasn’t.
Meanwhile, the neighboring Pine Island Glacier, a geothermal heat source from volcanic activity under the ice, has been confirmed. There is plenty of discussion on what this will mean, but the finding by no means contradicts the severe climate impacts in Pine Island Bay. Circumpolar Deep Water (CDW) “is the primary heat source for melting glacial ice and its increased presence on the Amundsen Sea continental shelf has been implicated in the rapid melting and grounding line retreat observed beneath the Pine Island Glacier...”
The study confirmed active “geochemical evidence of a volcanic heat source upstream of the fast-melting Pine Island Ice Shelf, documented by seawater helium isotope ratios at the front of the Ice Shelf cavity.”
In other words, the volcano is not directly melting the ice. The volcanism has the potential to heat the bedrock along with the friction generated by the ice grinding over the bedrock, which will make the land ice slide into the southern ocean that much easier.
Deniers will likely seize on this study to negate glaciology science. Elon Musk has unleashed trolls to berate, ridicule, and threaten climate scientists. Do not feed the trolls; they will come after you if you do.
The mantle 3He observed at the front of the Pine Island Ice Shelf, first in 2007 and again in 2014, reveals the presence of a volcanic heat source upstream of the Ice Shelf. The observation of this unique helium isotope signature, together with what is known of the bed forms and fluvial morphology of the Glacier suggests that this volcanic heat source lies within the Hudson Mountain range, and is driving a subglacial melt that subsequently crosses the ice shelf grounding line. Our calculations indicate that the volcanic heat source is comparable in magnitude to the active vent fields found along ocean spreading centers. The inferred heat supply is more than ten times the heat energy released by dormant (but not extinct) shield volcanoes on land.
These geochemical measurements provide an independent line of evidence of present day subglacial volcanism in Marie Byrd Land. They also support a growing list of studies revealing that regional volcanism is a recurring characteristic of the basal boundary beneath the WAIS. The present estimate of convective volcanic heat flux alone suggests a heat source of Q = 2500 MW, which is ~ 50% as large as the Grimsvötn volcano on Iceland, even before sensible and conductive heat flux have been accounted for. Simulations of the adjacent Thwaites Glacier may suggest that such a heat source will not significantly alter the subglacial melt rate in comparison with the high rate of friction58, but this could be circular argument if volcanic heat supply is already part of the recipe of processes leading to high velocity and frictional heating of the ice streams in the Pine Island and Thwaites Glacier. The magnitude and the variations in the rate of volcanic heat supplied to the Pine Island Glacier, either by internal magma migration8, or by an increase in volcanism as a consequence of ice sheet thinning61, may impact the future dynamics of the Pine Island Glacier, during the contemporary period of climate-driven glacial retreat.