Author: John

Monitoring the Greenland Ice Sheet from Space

As one part of my KNAP (Knowledge Acquisition Program)(basically, learn the stuff I need to know to be a competent researcher, consultant and writer), I’ve been undertaking a number of online courses. Another one ticked off the list this week was the ESA (European Space Agency) course “The Frozen Frontier: Monitoring the Greenland Ice Sheet from Space”.

This was really enjoyable. Apart from a few lectures near the end, it was pretty easy-going and informal, but with enough relevant solid data and knowledge to keep the “hard science” ethos satisfied. It’s also (glances at climate news) obviously topical, and make me twitch to visit an ice sheet (or have a return visit to a glacier). Though also with some fear; moulins are fascinating and dramatic, but not a cryospheric feature I want to get close to.

A screenshot from one of the videos which make up the ESA (European Space Agency) course "The Frozen Frontier: Monitoring the Greenland Ice Sheet from Space"
A screenshot from an online course about the Greenland ice sheet.

The course specifically answered a bundle of my questions; for example, how are the changes in the Greenland ice sheet and mass measured, and how accurate are these measurements. Plus a considerable amount of detail I didn’t know I didn’t know (IDKIDK is a ‘thing’ built into my KNAP) was included; for example, which satellites measured what, how frequently, and how is this data collected by researchers and scientists.

A caveat is that it’s a free course (formerly a MOOC) because it was produced around 2016/17 – so that’s where the data, findings, trends, conclusions and so forth end. It would be great if it was updated, but this is unlikely as the main presenter – and driving force behind the ‘Swiss Camp’ on the Greenland ice sheet – is deceased, due to an accident while undertaking fieldwork. However, the ESA provide several other related online courses in the wider climate-science field, and I’ll be working my way through those in future months.

The course is here:
https://www.esagreenlandmooc.org/

The iceberg which sank the Titanic

I mentioned earlier this year the question about how long glaciers last before they melt away. As a sudden thought, I did a search on one of the most (in)famous glaciers in history, the one which sank the Titanic.

There are various articles which take quotes and text from each other, but this one from Gizmodo (2012) contains this interesting text:

…the Titanic sank in the North Atlantic, rather than the Arctic, which means the currents must have taken it far south of where it was calved. Starting on the Greenland coast, it would have moved from Baffin Bay to the Davis Strait and then onto the Labrador Sea and, at last, the Atlantic.

The Titanic iceberg was one of the lucky ones, so to speak, as the vast, vast majority of icebergs melt long before they reach that far south. Of the 15,000 to 30,000 icebergs calved each years by the Greenland glaciers, probably only about 1% of them ever make it all the way to the Atlantic. On April 15, 1912, the iceberg was some 1,5000 miles south of the Arctic Circle.

The water temperature on the night of the Titanic sinking was thought to be about 28 degrees Fahrenheit, just below freezing. Such a temperature was of course lethally cold for all those passengers who had been forced to take to the open water to escape the sinking ship.

But such temperatures are far too warm to sustain icebergs for very long. The average life expectancy of an iceberg in the North Atlantic is only about two to three years from calving to melting. That means it likely broke off from Greenland in 1910 or 1911, and was gone forever by the end of 1912 or sometime in 1913.

So, even a (relatively) large iceberg, one large enough to gash open the Titanic, doesn’t last long until it melts away in certain ocean temperatures. (Obviously this is why icebergs aren’t a danger to shipping in the Mediterranean). Interesting to know.

As a side point, this article raises a particular theory as to the atmospheric conditions explaining why the lookouts on the ship didn’t see the iceberg until it was too late, while this 2012 article gives larger pictures of two of the candidate icebergs which caused the damage.

“Antarctic sea ice reaches lowest levels ever recorded”

(embarrasing moment: this article made me suddenly realise I wasn’t quite sure of the difference between Antarctic and Antarctica)

There’s an article in today’s Guardian about the recent and current retreat of the sea ice at the bottom of the world. It’s a very Guardianesque article about climate change: ominous, anxiety-inducing in some of the readership, but also with enough facts (which can be verified) and quotes from legitimate scientists to make for useful reading.

The article also mentiones the Thwaites glacier, which in media circles is somewhat the enfant terrible of glaciers. One of the reasons I’m exploring the world of MOOCs and other short online courses is to get answers to these questions:

  1. How do scientists measure sea ice expansion and retreat?
  2. If a glacier of volume X breaks off from an ice sheet, or calves from a glacier, how long does it take to melt?
  3. If X is very large (for instance, the aforementioned Thwaites coming off in one go), will its melting affect sea temperatures to any measureable (fraction of a) degree?

There’s other, more obscure, questions, but those are the three which keep coming to mind on reading articles like this. A preliminary search of academic papers doesn’t give clear or easy-to-understand answers, but maybe the right course(s) will?