Climate change
The climate of our planet has changed throughout its existence. This is attributed to tiny variations in the Earth’s orbit that change the amount of solar energy our planet receives. For millions of years such changes occurred over long periods of time giving rise to so-called ice ages and warm periods. However, recent changes in climate are of particular significance because they are likely caused by human activity. According to NASA, average global temperature has risen by almost 1°C since the year 1880. This warming is most likely caused by the emission of greenhouse gasses, such as carbon dioxide, methane or nitrous oxide. These gases act somewhat like the glass in a greenhouse, stopping the sun’s radiation from leaving the Earth’s atmosphere and converting it to heat energy. The main causes for rising emissions are burning coal, oil and gas, deforestation and animal agriculture.
Long-term climate record can be extracted by scientists from ice cores of glaciers, which preserve bits of atmosphere from thousands of years ago in tiny air bubbles.
Glaciers
A glacier is a body of dense ice with the ability to move. Glaciers are made up of snow which compresses into large, thickened ice masses over long periods of time. Glaciers are dynamic systems which grow (advance) and shrink (retreat) as a result of precipitation, melting and sublimation. When we say that a given glacier is advancing or retreating, we are referring to its terminus.
There are multiple types of glaciers, differing in size, shape and behaviour.
Ice sheets are enormous continental masses of glacial ice and snow with area of at least 50 000 square kilometres. During glacial periods of ice ages, when long-term reduction in the temperature of Earth’s surface and atmosphere occurs, ice sheets can advance into lower latitudes. During the most recent such period large parts of the Northern Hemisphere were covered by ice, including in Europe and North America. Currently ice sheets can only be found in Antarctica and Greenland.
Ice fields and ice caps are miniature ice sheets, so by definition they cover area smaller than 50 000 square kilometres. The difference between them is that ice caps are not constrained by topographical features while the topography of ice fields is determined by the shape of the surrounding land forms.
Mountain glaciers develop in high mountainous regions. Valley glaciers originate from them (or from ice fields) and spill down valleys, looking like giant tongues.
Hanging glaciers form when a valley glacier retreats and thins, leaving the tributary glacier high above the shrunken central glacier surface. They flow down mountainsides but stop abruptly, usually at cliffs.
Tidewater glaciers are valley glaciers which flow far enough to terminate in the sea. Their cycles of advance and retreat are longer and less affected by climate change than those of other glaciers.
Glacial crevasses
Crevasses are deep cracks in glacier ice caused by the stress of the ice moving over rocky terrain underneath. They are one of the main reasons why crossing a glacier may be dangerous. When covered by snow, crevasses can remain entirely hidden, so people can fall into them unexpectedly.
The cache
In order to attempt this cache you need to hike to and step on the Ortsveri glacier. Depending on the weather conditions and time of the year this may be a dangerous task and require specialist equipment. Please be careful and reasonable.
Send me the answers to the following questions and tasks within two weeks of logging the cache. I will contact you if some of your answers are incorrect.
1. Take a photo or screenshot of the reading of your GPS device between the two reference points provided. If you cannot take a photo, just write to me the coordinates that you measured.
2. Which type of glacier are you walking on?
3. At which time of the year have you visited the glacier? Was it covered by fresh snow?
4. Is the glacier retreating or advancing? How can you tell?
5. Have you seen any crevasses? Estimate the length and depth of the largest crevasse you have seen.
Answers can be sent in English or Polish. You are also encouraged to attach a photo of yourself on the glacier to your log.
I would be very grateful to a friendly cacher who speaks Georgian for providing a Georgian translation of this page. You will contribute to spreading general knowledge and I will thank you on the cache page!