EAWAG news 58e (July 2005)
Icy Discoveries (Entire volume)
| Editorial |
| (Screenversion 80 KB; Printversion 100 KB) |
| Martina Bauchrowitz |
| Lead Article |
| Ice and Climate (Screenversion 196 KB; Printversion 248 KB) Jürg Beer About 80% of all the fresh water in the world is trapped as ice in the two polar regions. This ice is an exceptionally good environmental archive, containing invaluable clues to hundreds of thousands of years of climate history. Information on past climate can also be obtained from analyses of historical records of lake ice cover, such as those from the Lej da San Murezzan (the Lake of St. Moritz) in Switzerland and Lake Baikal in Siberia. A somewhat puzzling substance, which looks like ice, is methane hydrate. It normally lies buried in the deep-sea sediment, but slight changes in environmental conditions could cause it to rise to the sea surface, in which case it would be possible for large amounts of the greenhouse gas methane to enter the atmosphere, resulting in a serious acceleration of climate warming. |
| Research Reports |
| A Long Road: from Greenland to
the Lab in Zurich (Screenversion 444 KB; Printversion 1.4 MB) Silvia Bollhalder and Irene Brunner Conclusions can be drawn about past environmental changes from telltale footprints left in environmental records. We are following one such hot lead in our investigations of the 3-km-long Greenland ice core. Layer for layer, the ice is examined to determine the concentrations of the radionuclide beryllium-10 (10Be). From such data it is possible to obtain information about past climate changes. About 10,000 ice samples have been prepared by the EAWAG laboratory in recent years for measurement in the ETHZ/PSI accelerator mass spectrometer. |
| Sun and Climate: Hot History from
Cool Ice (Screenversion 148 KB; Printversion 204 KB) Maura Vonmoos Paleoclimatic research has revealed that, far from being stable as previously assumed, the earth’s climate underwent large fluctuations. Over the past 10,000 years, it has been influenced primarily by the sun, volcanic activity and internal system fluctuations. Only since the Industrial Revolution has humankind joined in efficiently - in the last 20 years actually becoming the greatest contributor to the phenomenon of rising global temperatures. In order to understand the complexity of the climate system better, and to get a clearer picture of the human influence on the climate, it is necessary to examine the individual natural climate factors more closely. EAWAG is therefore undertaking a study of how greatly solar activity has varied in the past. |
| Why Did a Cold Period Follow on
the Heels of the Last Ice Age? (Screenversion 148 KB; Printversion 204 KB) Raimund Muscheler Large-scale climate changes in the northern Atlantic region were often associated with changes in ocean currents. That is also the case for the last cold phase of the Würm Ice Age, known as the Younger Dryas. At this time, a new cold period occurred and the northern Atlantic region relapsed from a moderate climate back to glacial conditions in the course of just a few decades. Climate indicators provide nevertheless contradictory information concerning the origins of this cold phase. EAWAG is on the trail of additional clues in an ice core from Greenland. |
| The Compass in the Ice (Screenversion 128 KB; Printversion 152 KB) Jürg Beer Everyone knows that a freely-moving magnetic needle will align itself to north, making it rather useful for finding one’s way in unknown areas or when visibility is poor. The principle of the magnetic compass has been known for more than a thousand years, and has been of inestimable value to navigators. Even migratory birds and other animals seem to have an inbuilt compass which permits them to home in on their destinations with uncanny precision. However, a compass several thousand years ago would not have pointed to the north pole; throughout the earth’s history, the geomagnetic field has reversed its polarity again and again. |
| Cosmic Radiation and Clouds (Screenversion 276 KB; Printversion 932 KB) Jürg Beer Ice cores provide abundant information about past climate changes. They can also provide answers to very specific questions and the means of testing hypotheses. One such hypothesis proposes that climate changes are caused primarily by changes in the intensity of cosmic radiation. If this is correct, it relegates the enhanced greenhouse effect to a secondary role - a politically explosive hypothesis which demands closer analysis. |
| Ice Cover on Lakes and Rivers -
Climate Trends Inferred from Historical Records (Screenversion 424 KB; Printversion 1.3 MB) David Livingstone The longer and colder a winter is, the earlier lakes freeze and the later they thaw. This is obvious intuitively even if we ignore the underlying meteorological complexities. EAWAG decided to take a closer look at this phenomenon by analyzing long series of historical observations of the timing of freeze-up and break-up of lakes such as the Lej da San Murezzan in Switzerland and Lake Baikal in Siberia. From these data, conclusions can be drawn about past and future climate forcing. |
| The North Atlantic Oscillation
- Does it Affect the Timing of Break-up of Northern Hemisphere Lakes?
(Screenversion 256 KB; Printversion 588 KB) David Livingstone The North Atlantic Oscillation is a large-scale climate phenomenon that affects the climate of much of the northern hemisphere in winter and spring. EAWAG found that it also affects the timing of ice break-up on northern hemisphere lakes. The area of influence of the North Atlantic Oscillation has shifted over the past 130 years, with an increase in its influence in Siberia and a decrease in North America. |
| Ice On Fire - Methane Emissions
to the Atmosphere (Screenversion 284 KB; Printversion 644 KB) Carsten Schubert The stories told by seafarers over the centuries about burning icebergs were long considered superstition until they were finally confirmed near the end of the last century. The “burning icebergs” are caused by pieces of methane hydrate, a compound of ice and methane deposited in the sediments of the seabed, occasionally floating to the sea surface. All it takes is for them to be struck by lightning and we really can see burning ice. Around 10,000 billion tonnes of methane are bound in the form of gas hydrates in the sediments of the world’s oceans. In the EU project CRIMEA, EAWAG is investigating the occurrence of methane in the Black Sea. |
| In Brief (Screenversion 152 KB; Printversion 460 KB) |
Please feel free to submit questions or suggestions any time to the editor Martina Bauchrowitz.