Glaciology and Quaternary Geology – serie

Proceedings of the Symposium on Glacier Fluctuations and Climatic Change, held in Amsterdam, June 1-5, 1987

Antarctica, the sixth continent, was discovered more than 160 years ago. Since then this large, mysterious continent of ice and penguins has attracted world interest. Scientific expeditions from various countries have begun to study the geographical and natural conditions of the icy continent. Systematic and comprehensive inves­ tigations in the Antarctic started in the middle of our century. In 1956 the First Soviet Antarctic Expedition headed to the coast of Antarctica. Their program included studies of the atmosphere, hydrosphere and cryosphere. Thirty years have since passed. Scientists have unveiled many secrets of Antarctica: significant geophysical processes have been investigated, and a large body of new information on the Antarctic weather, Southern Ocean hydrology and Antarctic glaciers has been obtained. We can now claim that the horizons of polar geo­ physics, oceanology, and particularly glaciology, have expanded. Scientific inves­ tigators have obtained new information about all Antarctic regions and thus have created the opportunity to use the Antarctic in the interests of mankind.

Glaciers or ice sheets are natural accumulations of ice possessing in­ trinsic motion, which have appeared on the Earth's land surface as a result of the accumulation and transformation of precipitation [2]. Only a very small portion of the surface of the land is now covered by glaciers, and at low latitudes they are found justat high elevations, on mountain slopes. However, glaciers are known to play very important roles in shaping the topography of the Earth, in determiningits past, present, and future climate, and in creating the state of the world Ocean. Recently there has also been a marked increase in the practical value of our knowledge about glaciers, as a part of the human habitat and as a factor affecting the economy. Interest in glaciers on other planets is also growing. Voyages of spacecraft to Jupiter, for instance, have shown that some Jovian satellites possess ice sheets tens of kilometers in thickness.

The problem of ice destruction comes most frequently to our attention in engineering glaciology and ice engineering because it is essential in the solution of many problems in the polar regions of the Earth. Ice destruction (like the destruction of any other material, in principle) is a complex problem at the junction of solid-state physics, continuum mechanics, and materials science. Ice, particularly sea ice, is characterized by known anomalies that can be explained by the simultaneous occurrence of solid, liquid and gaseous phases. Even minor temperature fluctuations cause changes in the relationship of these phases and, as a consequence, change the physico-mechanical properties of ice. New hydraulic engineering tasks, associated with the destruction of such a complex material, demand continuous improvement of methods and techniques. The present authors have brought these together in a form which is convenient for a wide range of users. This book covers only local ice destruction, by means other than icebreakers, requiring comparatively low consumption of power in proportion to the volume and mass of destroyed ice. Problems of natural ice destruction under the influence of solar radiation, tidal, wind and wave factors are not dis­ cussed. Mechanical and thermal methods were the first of many to be used for ice destruction. Their application has involved a greater num­ ber of techniques, so the first two chapters are the longest.

Few scientists doubt the prediction that the antropogenic release of carbon dioxide in the atmosphere will lead to some warming of the earth's climate. So there is good reason to investigate the possible effects of such a warming, in dependence of geographical and social­ economic setting. Many bodies, governmental or not, have organized meetings and issued reports in which the carbon dioxide problem is defined, reviewed, and possible threats assessed. The rate at which such reports are produced still increases. However, while more and more people are getting involved in the 'carbon dioxide business', the number of investigators working on the basic problems grows, in our view, too slowly. Many fundamental questions are still not answered in a satisfactory way, and the carbon dioxide building rests on a few thin pillars. One such fundamental question concerns the change in sea level associated with a climatic warming of a few degrees. A number of processes can be listed that could all lead to changes of the order of tens of centimeters (e. g. thermal expansion, change in mass balance of glaciers and ice sheets). But the picture of the carbon dioxide problem has frequently be made more dramatic by suggesting that the West Antarctic Ice Sheet is unstable, implying a certain probability of a 5 m higher sea-level stand within a few centuries.

Proceedings of the Symposium on Glacier Fluctuations and Climatic Change, held in Amsterdam, June 1-5, 1987

3 new biota and extinction of others, and extensive soil erosion reaching almost catastrophic proportions have led to desertification of many upland areas and abandonment by local populations. The role of climatic change as opposed to deforestation and sheep grazing in creating these new environments has proved a further issue of great controversy. While our understanding of historic environmental changes remains inadequate, our knowledge of processes that are modifying the present-day landscape is also sparse and selective. Little is known of active periglacial processes, slope instabilities, and rates of soil erosion by slope wash and aeolian transport. Coastal processes of erosion and beach formation have been studied only locally. Most of our information on recent or active processes comprises records of glacier fluctuations, volcanic eruptions and jOkulhlaup events, but sti11little is known of the mechanisms and processes of landscape change effected by these events. This volume of papers, based on a conference sponsored by the Quaternary Research Association and the Geologists Association and held at the University of Aberdeen in April 1989, addresses many of these crucial uncertainties regarding environmental changes in Iceland from the Lateglacial onwards. The papers make a major contribution to dispelling many earlier uncertainties and clarifying areas of controversy. Many of the papers challenge traditional and poorly supported ideas, replacing them with hypotheses based on new data and new insights derived from the expansion of wider scientific expertise and theory. The volume focuses on three major areas of research in particular.

The problem of ice destruction comes most frequently to our attention in engineering glaciology and ice engineering because it is essential in the solution of many problems in the polar regions of the Earth. Ice destruction (like the destruction of any other material, in principle) is a complex problem at the junction of solid-state physics, continuum mechanics, and materials science. Ice, particularly sea ice, is characterized by known anomalies that can be explained by the simultaneous occurrence of solid, liquid and gaseous phases. Even minor temperature fluctuations cause changes in the relationship of these phases and, as a consequence, change the physico-mechanical properties of ice. New hydraulic engineering tasks, associated with the destruction of such a complex material, demand continuous improvement of methods and techniques. The present authors have brought these together in a form which is convenient for a wide range of users. This book covers only local ice destruction, by means other than icebreakers, requiring comparatively low consumption of power in proportion to the volume and mass of destroyed ice. Problems of natural ice destruction under the influence of solar radiation, tidal, wind and wave factors are not dis­ cussed. Mechanical and thermal methods were the first of many to be used for ice destruction. Their application has involved a greater num­ ber of techniques, so the first two chapters are the longest.

Few scientists doubt the prediction that the antropogenic release of carbon dioxide in the atmosphere will lead to some warming of the earth's climate. So there is good reason to investigate the possible effects of such a warming, in dependence of geographical and social­ economic setting. Many bodies, governmental or not, have organized meetings and issued reports in which the carbon dioxide problem is defined, reviewed, and possible threats assessed. The rate at which such reports are produced still increases. However, while more and more people are getting involved in the 'carbon dioxide business', the number of investigators working on the basic problems grows, in our view, too slowly. Many fundamental questions are still not answered in a satisfactory way, and the carbon dioxide building rests on a few thin pillars. One such fundamental question concerns the change in sea level associated with a climatic warming of a few degrees. A number of processes can be listed that could all lead to changes of the order of tens of centimeters (e. g. thermal expansion, change in mass balance of glaciers and ice sheets). But the picture of the carbon dioxide problem has frequently be made more dramatic by suggesting that the West Antarctic Ice Sheet is unstable, implying a certain probability of a 5 m higher sea-level stand within a few centuries.

Glaciers or ice sheets are natural accumulations of ice possessing in­ trinsic motion, which have appeared on the Earth's land surface as a result of the accumulation and transformation of precipitation [2]. Only a very small portion of the surface of the land is now covered by glaciers, and at low latitudes they are found justat high elevations, on mountain slopes. However, glaciers are known to play very important roles in shaping the topography of the Earth, in determiningits past, present, and future climate, and in creating the state of the world Ocean. Recently there has also been a marked increase in the practical value of our knowledge about glaciers, as a part of the human habitat and as a factor affecting the economy. Interest in glaciers on other planets is also growing. Voyages of spacecraft to Jupiter, for instance, have shown that some Jovian satellites possess ice sheets tens of kilometers in thickness.

Antarctica, the sixth continent, was discovered more than 160 years ago. Since then this large, mysterious continent of ice and penguins has attracted world interest. Scientific expeditions from various countries have begun to study the geographical and natural conditions of the icy continent. Systematic and comprehensive inves­ tigations in the Antarctic started in the middle of our century. In 1956 the First Soviet Antarctic Expedition headed to the coast of Antarctica. Their program included studies of the atmosphere, hydrosphere and cryosphere. Thirty years have since passed. Scientists have unveiled many secrets of Antarctica: significant geophysical processes have been investigated, and a large body of new information on the Antarctic weather, Southern Ocean hydrology and Antarctic glaciers has been obtained. We can now claim that the horizons of polar geo­ physics, oceanology, and particularly glaciology, have expanded. Scientific inves­ tigators have obtained new information about all Antarctic regions and thus have created the opportunity to use the Antarctic in the interests of mankind.