Glacier water pockets

Some days ago, I was watching the episode 'ice' from the BBC documentary series Earth. In this episode Dr Iain Stewart shows us a 'back door' to a glacier ("he sees a glacier in action from below"). Here he saw that the glacier has holes filled with water, these pockets can contain up to about twenty litres of water. The commentator puts forth the hypothesis that these pockets are generated by the pressure of the ice mass above and that these holes make the glacier less rigid and hence move faster.

The beautiful thing about glaciers is that they are rivers of ice, really behaving like a liquid. The bottom meter (or so) is even filled with sediments (sand, gravel, stones) like they are picked up by the flow and then whirled into the ice. (We even have a word for these processes: glaciofluvial.)

A typical glacier will move several meters (up to about 30 meters) a day, with the bottom parts moving slower due to the friction with the bed. However, the enormous pressure in the bottom parts of the glacier, make the ice more fluid than that on the top layers. During the flow the top layers of the glacier will often crack, because this part (the 'fracture zone') is so rigid.

Now, I was wondering. May it not be possible that the pockets of water in the lower parts of the glacier are a result of a solid phase water being forced into the liquid phase by the energy the glacier has to absorb on its way?

I tried to find an answer on this wonderfully informative site: Martin Chaplin's Water structure and science (here: phase diagrams). however, I could not find the answer there easily. Probably, because most of the information on the site is too specialised for me (or maybe even just too difficult and complicated).

By the way, it seems that the water in these pockets can't be colder than -20°C; looking at the phase diagram from professor Chaplin's site.


What a wonderful place we live in!

Empty Seas

We really ought to worry about our influence on our precious Mother Earth. I take this very serious, because I believe our world is sacred. The main problem is that we do not understand fully the impact of our actions.

However, since this is the case, I tend to scrutinize all warnings and all solutions. Of course, I do not nearly have enough knowledge of the subject to come up with solutions myself, let alone penetrate the complexity of all consequences. The reason I write this is not to cause doubt, on the contrary! I want to spread awareness of the problems we are facing and show that we should not make rash decisions.

Lately people started warning us for the danger of empty seas: our pollution and our fishing may very well tip the population size of fish, causing them to spiral to extinction. This also may cause famine between animals such as sea birds and dolphins. I strongly hope that fishing becoming unprofitable because of the small catches, will happen before fish population levels dropping below a critical sustainable level. Even then there is hope: from that point on, fish population may reach a new 'stable region' (I mean in phase space, not in the waters of the Earth).

At first I had hoped that fish in the oceans may migrate vertically: they may adapt and start to live at depths where they are save from fishing nets. (I have to find out: Will there be enough nutrients and inflow of energy to sustain a new ecosystem on that depth?) Unfortunately, deep seas are already targeted by trawlers, that can easily catch fish at depth at over 1km.

Who knows, maybe fish will become extinct locally or even globally. That would be terrible. If 'only' certain regions of oceans will become completely depleted, new pioneer species may step in, followed by others. Or maybe, the extinction of fish will cause algae and plants to flourish enormously in the oceans, resulting in a gigantic increase of CO2 absorption from the atmosphere thus relieving part of the climate problem. On the other hand, maybe there will be collapse of the global ecosystems causing the world to wander on a chaotic path. Who knows where that will end up.