Exploration continues
Ice, Ice, Ice. We have seen a lot of it on this enjoyable and scientifically exciting cruise. From huge floating icebergs, over 25 km long and 450 m in height (from bottom to top, with 9/10 of the berg below the waterline) to little ice floes, enjoying their last few hours of existence. Some of the ice comes from the freezing of sea water, mainly in the long (Southern hemisphere) winter. The rest of the ice comes from the snow over the Antarctic continent over the ages having built ice sheets averaging some two kms thick, which flow over the Antarctic continent and out to sea at the rate of roughly 500 m/year.
Iceberg at sunrise
Approximately a tenth of the surface of the Earth is covered in ice. It plays an important role in determining the climate of the Earth, in particular by reflecting between a half and three-quarters of the energy of the sunshine incident upon on it, compared with an average of 1/3 for the rest of the Planet (close to 1 for the sea surface, which stretches over 7/10 of the surface planet, and between 1/5 and 2/5 for land).
The formation and melting of the ice also plays an important climatic role. When ice forms from sea water, of salinity approximately 3.5% by mass, the ice formed contains very little salt. The ‘released’ salt mixes with the surrounding water, making it more dense. The dense water sinks (due to the actions of gravity) to the bottom of the ocean and then flows northwards in a current which been detected (by chemical means) as far 45 degrees north.
A large 30km long iceberg we have affectionately named Big Bird.
The Antarctic was virtually unknown 100 years ago. Scott’s heroic, but failed, expedition brought him and four others to the South Pole a hundred years ago last week (on 17 January 1912). They found there a note from the Swedish Explorer, Amundson, wishing them well and telling them that he had been first to the Pole by a mere thirty five days.
While the Antarctic is now a great tourist attraction and place for scientific data collection, it still remains part of the ‘great unknown’. What is known is that the climate of the Earth is heavily influenced by processes in the Antarctic that we only loosely understand.
The JCR at sunrise.
Back to the journals.