|Fig. 1 Area 'E' WOD Zone 5606|
It was to follow the post on the Ross Sea, and WOD Zone 3716 there.
The reason for selecting WOD Zones 3716 and 5606 is because they have more glaciers than any other zones in Antarctica.
For example, Zone 3716 has 106 glaciers and Zone 5606 has 325 glaciers (see the links to individual glaciers at both zones at this link: Antarctica's Glaciers by Ocean Area and WOD Zone - 2.
|Fig. 2 Water & Melt Temperatures|
Fig. 1 indicates the location of WOD Zone 5606 in Area 'E'.
The graph at Fig. 2 presents the Conservative Temperature (gsw_CT_from_t) at three depth levels along with the water temperatures after those cold temperatures melt the even colder ice at the frontal face of the glacier.
Some readers may wonder why I use three depth layers, so, take a look at the graphs at Fig. 3a and Fig. 3b.
|Fig. 3a Water Temperatures Only (33 depths)|
Even though I have a database of in situ measurements at each one of the 33 levels, I average those CT values into three levels (0m - 700m, >700m - 2000m, and >2000m) to avoid too many lines on a graph.
I also want to discuss some of the dynamics that cause frontal melting because that dynamic is more important than generally realized:
"Frontal melting is a process which has long been neglected by glaciologists,(Frontal processes on tidewater glaciers). Frontal melt is what causes the grounding line to "fall back" (see Fig. 4).
but which has been repeatedly shown to be important both from a large-scale mass-balance perspective, and for a process-based understanding of tidewater glacier behaviour. The recent development of a range of models of plume-driven melting, as well as a renewed interest in the measurement of frontal melt rates, have shown how little this process is understood, and have highlighted the need for an approach which synthesizes both data and modelling."
Fig. 3b Water and Melt Temperatures (33 depths)
One result of frontal melt is that the grounding line position proceeds in the opposite direction from the glacier's forward direction.
|Fig. 4 Tidewater Glacier Melt Factors|
For both general and specific detail on the issues, the following paper also helps one to understand some more of the main details: Antarctic Glaciers Lost Stunning Amount of Ground in Recent Years.
One take away is that Antarctica has been a mythical place.
Going back a decade or so, some managers in science venues did not know what was going on either because they did not want to, or were told to not want to:
"I suspect the existence of what I call the `John Mercer effect'. Mercer (1978) suggested that global warming from burning of fossil fuels could lead to disastrous disintegration of the West Antarctic ice sheet, with a sea level rise of several meters worldwide. This was during the era when global warming was beginning to get attention from the United States Department of Energy and other science agencies. I noticed that scientists who disputed Mercer, suggesting that his paper was alarmist, were treated as being more authoritative.(On Thermal Expansion & Thermal Contraction - 8, quoting Dr. Hansen). They looked over the fact that Antarctica is the largest desert on Earth, and therefore, by definition, could not receive enough snowfall to offset the ice mass loss taking place.
It was not obvious who was right on the science, but it seemed to me, and I believe to most scientists, that the scientists preaching caution and
downplaying the dangers of climate change fared better in receipt of research funding. Drawing attention to the dangers of global warming may or may not have helped increase funding for relevant scientific areas, but it surely did not help individuals like Mercer who stuck their heads out. I could vouch for that from my own experience. After I published a paper (Hansen et al 1981) that described likely climate effects of fossil fuel use, the Department of Energy reversed a decision to fund our research, specifically highlighting and criticizing aspects of that paper at a workshop in Coolfont, West Virginia and in publication (MacCracken 1983).
Fig. 5 Potential Sea level rise
I believe there is a pressure on scientists to be conservative. Papers are accepted for publication more readily if they do not push too far and are larded with caveats. Caveats are essential to science, being born in skepticism, which is essential to the process of investigation and verification. But there is a question of degree. A tendency for `gradualism' as new evidence comes to light may be ill-suited for communication, when an issue with a short time fuse is concerned."
Adding more deadly cold water to the Southern Ocean means that it too will eventually absorb energy from the warming ocean and then melt even more ice (Hot, Warm, & Cold Thermal Facts: Tidewater-Glaciers, 2, 3, 4).
The tidewater glaciers of Antarctica and Greenland are an existential threat (as shown by Fig. 5), because if only a small percentage, about one and a half percent (~1.5%), of their ice melts it will destroy the sea trade upon which current civilization relies (80.32m * 0.015 = 1.2048m, = 3.95275591 ft).
That four feet of water will take out the sea ports (The Extinction of Robust Sea Ports, 2, 3, 4, 5, 6, 7, 8, 9).
The previous post in this series is here.