Mysterious Zones of Antarctica

Ocean Currents & Zones of Antarctica

I. Begin Here

Today we take a look at the temperatures of the tidewaters of the Antarctic coast.

I am talking about the tidewaters that are melting the tidewater glaciers (Hot, Warm, & Cold Thermal Facts: Tidewater-Glaciers, 2, 3, 4).

We only skim the surface by looking at measurements from the surface down to ~410 feet (125 meters), but in future posts of this series we will look as deep as there are measurements available from my SQL server filled with some 1.3 billion measurements from SOCCOM and WOD.

Area A [West Indian]

Area B [East Indian]

Area C [Ross]

Area D [Amundsen]

Area E [Bellingshausen]

Area F [Weddell]

Don't be put off by the notion of skimming the surface, because the purpose in this series is not dependent on depth.

It is more dependent on depth perception.

This introductory post has the purpose of preparing readers to become familiar with the mystery of the warming of the deadly cold Antarctic waters.

If you will, notice the different patterns (graphs Area A through Area F).

The variations are caused by different seawater temperatures in each zone.

Compare them with the graphic at the top-left of this post and you will begin to get my drift.

These are fingerprints, if you will, of impacts on Antarctica from different events, different forces, and different factors.

II. Area D, The Amundsen

For example, in the graph of Area D [Amundsen Sea] the pattern begins circa 1992 with a decrease in seawater temperature at every depth level down to 125 meters.

Some of the seawater temperatures descend steeply for two years, until circa 1994, then level out a bit until circa the year 2000.

However, two of those depth levels descent more slowly (purple & green lines) until circa the year 2000.

In about the year 2000, they all begin to have warmer temperatures until about the year 2005.

In about the year 2005 they all of a sudden go their separate ways in terms of seawater temperature.

It is as if Conservative Temperature (CT) morphed into 'Chaotic' Temperature.

III. The Measurement Years

The graphs begin in the same year, 1992, to make it easier to compare the patterns in them.

The graphic at the top left of this post shows potential ocean current sources.

The currents are changing so we may not have as much of an understanding of them now.

But the fact that the seawater temperatures in Antarctic Zones are inexplicably not marching to the same beat, the same drum, and/or the same drummer, IMO, indicates an impact from a major source or sources.

IV. The Winds Of Change?

I have passed upon this mystery, in a smaller scope (Totten Glacier), in at least one previous post:

There are two approaches to explaining the massive changes taking place in Antarctica's tidewater glaciers.

One of those approaches has a limited or narrow outlook or scope, as exemplified by this paper (Wind Causes Totten Glacier Melt).

Why one glacier would melt because of surface wind and others would not is a suspicious hypothesis, plus the WOD Zone records do not show what the authors "thought to be driven by a variable supply of warm, salty, modified circumpolar deep water" (ibid).

The graphs (discussed below) based on in situ ocean water temperatures do not bear that out.

Another approach links global events into the causation picture (AMOC Weakens, Same), and yet another targets other currents (Carbon Brief).

Those and other global events have an impact on the Southern Ocean:

"Researchers have been worried about an Atlantic slowdown for years. The Atlantic serves as the engine for the planet’s conveyor belt of ocean currents: The massive amount of cooler water that sinks in the North Atlantic stirs up that entire ocean and drives currents in the Southern and Pacific oceans, too. “It is the key component” in global circulation, says Ellen Martin, a paleoclimate and ocean current researcher at the University of Florida. So when the Atlantic turns sluggish, it has worldwide impacts: The entire Northern Hemisphere cools, Indian and Asian monsoon areas dry up, North Atlantic storms get amplified, and less ocean mixing results in less plankton and other life in the sea."

(How Climate Change Could Jam Ocean Circulation, emphasis added). There is a reason to look for global sources of impact on the Southern Ocean.

Local phenomena have a local (limited) impact, so they are not as likely to be a significant cause of continent-wide changes.

(Antarctica 2.0 - 6). Regular readers know that I am skeptical of the local wind hypothesis.

The main winds blow from west to east, and generate the largest ocean current on the globe:

The Antarctic Circumpolar Current (ACC) is the most important current in the Southern Ocean, and the only current that flows completely around the globe.
...
The ACC is arguably the "mightiest current in the oceans" (Pickard and Emery, 1990). Despite its relatively slow eastward flow of less than 20 cm s-1 in regions between the fronts, the ACC transports more water than any other current (Klinck and Nowlin, 2001). The ACC extends from the sea surface to depths of 2000-4000 m and can be as wide as 2000 km.

(The Antarctic CP Current, emphasis added). That would seem to make ocean currents the primary suspect for subsurface seawater changes.

That is especially so considering the merits:

"The vast Southern Ocean, which surrounds Antarctica, plays a starring role in the future of climate change. The global oceans together absorb over 90 percent of the excess heat in the climate system and roughly three-quarters of that heat uptake occurs in the Southern Ocean. In addition, the global oceans absorb around 25 percent of anthropogenic carbon dioxide emissions and the Southern Ocean alone accounts for about half of the uptake of CO2.

Despite its critical role in our climate system, the Southern Ocean has gone almost completely unobserved. Scientists have struggled to gather precise measurements because of the harsh environment and extreme remoteness. The changing dynamics of the Southern Ocean will in turn drive key aspects of our future climate, including how sensitive the Earth will be to further warming and increases in carbon dioxide emissions. As a result, improved observations are crucial to helping scientists understand and predict how our climate will change."

(Antarctica 2.0 - 3, quoting Climate Central, emphasis added). Seems like a slam dunk to me.

V. Conclusion

I am not convinced that these fingerprints shown in today's graphs that detail chaotic seawater temperature changes are caused by weaker and temporary local winds.

In my opinion these are the results of deep ocean currents running amok (The oceans’ circulation hasn’t been this sluggish in 1,000 years. That’s bad news).

The next post in this series is here.

---

---