Eustasy video

Eustatic sea-level changes refer to the world-wide changes in the height of the sea surface with respect to land areas.  In regards to long term climate changes, eustatic sea-level change is largely due to changes in the amount of water locked up in the ice sheets and mountain glaciers.  As an ice sheet melts, sea level rises and as ice sheet grows, sea level falls.  This process also happens on shorter timescales, and the research project I am working on at the moment is looking to see how changes in the ice sheets has affected sea level over the last 500 years in the North Atlantic.

A logical idea, however, I thought it would be fun to make a video to show the students this process as it is one of the main causes of sea-level change.  I slightly underestimated how long it would take my freezer to make a mini ice sheet (with blue food coloring – to make it more interesting and make the sea level change clearer), however, once my ice sheet had frozen, I used time lapse photography to create a video of the ice melt causing eustatic sea-level rise in an 'ocean' in my kitchen!

The finished product:

One must be aware that this video suggests the sea level rises uniformly across the whole ocean as the ice sheet melts.  In regards to ice sheets and mountain glaciers, the picture isn’t that simple as a big lump of ice has its own gravitational field, in the same way as the moon does. When the ice sheet is at its biggest, the sea is pulled towards the ice, resulting in higher sea level closest to the ice sheet.  When the ice melts, the ‘ocean tide’ moves away from the ice sheet and the greatest sea level rise is in fact furthest away from the ice sheet.  More details can be found in this research paper.  Our present research project trys to pick out these patterns of sea-level change around the North Atlantic to work out which ice sheets may be contributing to sea-level change.

Past ice sheets

For a geographer that studies past climate the idea of areas of the world being covered by ice in the past that are now forest, fields and towns seems quite normal, but for many school students that seems a very bizarre concept.

I used the excellent video developed by the Aberystwyth University Glaciology research group to show the students how big the British and Irish ice sheet was and how it grew and shrunk during the last glaciation.  I also created an image to show the students thick the ice sheet was.  This somewhat blew their minds!

Preparation

Reflecting back on my placement, I was very nervous beforehand as I was not sure how the students would respond to me, and the ideas I was trying to get across.  As a result, I wrote quite detailed lesson plans, which looking back was very beneficial.  I am a bit overly organised/keen at times so this does reflect my working style, however it did mean that when I walked into the first class I had some idea of what I was doing, which calmed my nerves.  My plans did not always go accordingly, based on the particular class, but it gave me something to work around.

One suggestion that the Researchers in Residence trainers gave us, was the use of word searches.  Most classes have a real range of students in them, and inevitably, there will be students who fly through the tasks or those whose imaginations don’t run away with them.  Having some word searches on the theme of the lesson was a lifesaver.  I was shocked how much the students loved them: noisy students suddenly became silent.  I used this website to create my own sea level/past climate word searches.