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Didactic Geology / Botany Trail
Climate Change
Didactic Geology / Botany Trail
The Geology / Botany Trail was created together with the World Wildlife Fund
and was carved out ot existing hiking trails. Hike trough the canton's largest "art gallery", admiring the beautiful rock formations. The signs explain how each came out. Lucky hikers may find fossilized animals and plants that are millions of years old. There are some rather impressive areas where this can be found on the Chli Horn.
Hikes
3-D Flight
Climate Change in Central Switzerland
Since the beginning of Earth’s history, the climate has always been subject to natural varia-tions. Since the Pleistocene (around 1,750,000 years ago), these climate variations began to intensify. For example, the Ice Ages would see glaciers advance as far as the Swiss Mittel-land, while during the Interglacials the climate became considerably warmer. Around 10,200 years ago (start of the Holocene), the last significant glacial phase came to an end and tem-peratures began to rise.
In around 1850 the Alpine glaciers would advance for the last time. Since then, the climate has grown steadily warmer.
Greenhouse effect
The presence of greenhouse gases in the atmosphere is important for supporting life on Earth. They change the radiation balance of the Earth, letting through short-wave solar radia-tion (UV rays) while partially repelling long-wave irradiation (infrared radiation). This process heats the earth, making it habitable. However, this natural phenomenon is intensified further by the man-made production of greenhouse gases.
Fig. 1: In addition to water vapour, the major greenhouse gases are carbon dioxide (CO2), methane (CH4) and laughing gas (N2O). Since the industrial revolution began over 200 years ago, their concentration in the atmosphere has increased substantially, and is currently at its highest level for 420,000 years.
The last time that CO2 had risen so rapidly was at least 20,000 years ago. Two factors in par-ticular lie behind this rise: the burning of fossil fuels (crude oil, coal and gas) and changes in land use, especially deforestation.
Data on CO2 emissions could not make the point any clearer: around 75% of CO2 emissions over the last 20 years were due to the burning of fossil fuels and around 25% to changes in land use.
Fig. 2: The graph shows the parallel rise in CO2 levels in the atmosphere and average annual temperatures since industrialisation began. The central factor behind this rise in CO2 levels is the burning of fossil fuels.
Observations
Rising temperatures
Average global temperatures are set to rise by between 1.4 and 5.8°C in the space of little over a century (1990-2100 period). This is twice to ten times as high as the rate of global warming observed during the course of the twentieth century, most probably an unprece-dented occurrence since the end of the last Ice Age around 10,000 years ago. However, this rise will vary considerably across regions. For example, temperatures in the Alps and Swit-zerland in general are likely to exceed the global average. Europe will experience more heat waves and fewer days when the temperature falls below zero.
Melting of glaciers
Alpine glaciers are especially sensitive to climate change. A glacier has an accumulation zone where snowfall is collected and is turned into ice, and an ablation zone, located in the toe-zone, where the glacial ice melts. This balances out ice accumulation and ice ablation.
However, climate change upsets this balance in the following ways:
• Warmer and drier springs: lower levels of snow in accumulation zones which rapidly melts -> preventing the accumulation of glacial ice.
• Warmer summers and autumns with higher radiation levels: no protective snow cover -> glaciers are directly exposed to solar radiation and shrink dramatically.
• Winters with little snowfall: lack of snow collected in the accumulation zone.
This means that glaciers not only retreat but suffer a considerable reduction in their volume.
Fig. 3: The Titlis glaciers have retreated by around 500 m and their volume has shrunk dra-matically. If temperatures continue to rise, they will have vanished completely by the end of this century. This has serious repercussions. For instance, the water balance in the region will be severely affected, since the glacier has served to date as a reservoir for drinking wa-ter. Furthermore, the regional tourist industry will also undoubtedly suffer due to the loss of its major attraction.
Thawing permafrost and ice crevices
In permafrost zones the deepest levels of subsoil remain frozen throughout the year. Only the upper layers melt in summer. In the Alps, this process occurs at higher altitudes.
Rising temperatures mean that the frozen subsoil steadily begins to melt. Slopes, which were once frozen, thaw and become unstable. Ice crevices begin to melt, causing the rocks also to become unstable.
Greater storm frequency
In the future, extreme weather events, such as the “Lothar” hurricane of 26 December 1999, will occur with increasing frequency. Lothar caused extensive damage. In Switzerland, for example, 14 people lost their lives during the storm, and a further 15 during the clean-up op-erations. The total cost of damage to forests, buildings and vehicles, during the two hours when the hurricane wreaked havoc, was CHF 1,780 mn. Over 20% of buildings in the canton of Nidwalden suffered damage. On the Stanserhorn, over 80% of the forests which had pro-vided protection against natural hazards were destroyed.
Rainfall
Central and northern latitudes in general will see rainfall levels rise. Models show that the Alps will have less rainfall in the summer but more during winter. Even today, extreme weather events, such as torrential downpours, extreme heat waves and droughts, seem to be a more common occurrence than before.
Rising sea levels
The global mean sea level is set to rise by between 9 cm and 88 cm over the next one hun-dred years (1990-2010 period). The main cause is the thermal expansion of the oceans.
Biodiversity, agriculture and tourism
Vegetation and forest line elevations are retreating. In lower-lying areas, plants and animals are migrating from warmer regions. It is not beyond the realms of possibility that in the space of one hundred years, Stans will have olive trees where fruit trees once grew.
Plants come into flower and bear fruit ever earlier, while the vegetation period grows ever longer. If summer droughts do not lead to water shortages and crop failures, crop and fodder production increases in low-lying areas. In Alpine regions, the summer pasturing of cattle has grown in importance.
Snow reliability in the tourist resorts of central Switzerland will fall by up to 80%.
Consequences
Increasing natural risks
Natural hazards such as mudslides, landslides, rock falls, erosion, unstable soils, avalanches, and floods will increase as the result of extreme weather and the melting of the permafrost.
These natural hazards cause both human and material damage. However, integral risk man-agement (well-planned approach to dealing with natural disasters) can help mitigate such events. This involves:
• Protective planning measures (spatial planning, including hazard maps and zoning plans)
• Organisational protection (e.g. contingency planning and organisation, warning sys-tems, evacuations and cordoning off at-risk areas)
• Structural protection (e. g. protective structures and building protection)
• Biological protection (protective forests, nature and forest conservation)
Integral risk management measures must aim for the greatest possible effectiveness at the lowest possible cost.
Every 12 years, insurance claims worldwide are doubling. If this current trend continues, total annual damage costs will be in excess of USD 1 billion by 2050.
Large areas throughout the world are at risk of flooding due to rising sea levels. Droughts and water shortages pose a threat particularly to developing countries, which do not have the necessary financial resources to invest in natural risk protection. These regions will suffer the most from climate change.
Health
Climate change also affects our health: arid and semi-arid regions will experience more droughts and water shortages, which in turn will lead to famine and illnesses due to the poor quality of drinking water.
In temperate latitudes, respiratory illnesses, allergies as well as the spread and frequency of infectious disease are on the rise. Other environmental factors also play their part - air pollu-tion, altered pollen activity, greater prevalence of insects and ticks.
Fig. 4: The torrential rains of August 2005 caused extensive damage throughout Switzerland. In the canton of Nidwalden alone the cost of repair work came to around CHF 127 million. The photo of the North base of the Stanserhorn: mudslides caused damage to the hospital, residential property and the Stanserhorn railway line. However, a comprehensive protection plan helped alleviate the situation. One of the consequences of global warming is that storms will occur with greater frequency.
Measures
Climate change has a multitude of direct and indirect effects on us and our environment. Many correlations and repercussions remain unclear. However, one thing is sure: to mini-mise the disruption of the radiation balance and climate change, greenhouse gas emissions must be curbed. This is only possible if the use of fossil fuels (crude oil, coal, gas) is drastically reduced.
Human-induced climate change will persist for several centuries, because CO2 is retained in the atmosphere for an extremely long time. If these levels are to be capped, global emissions will have to be reduced to well below current values. This will require internationally coordi-nated, economic and political measures.
Text: Lea Odermatt, Geologist and Markus Baggenstos, Biologist
Grafik: Lea Odermatt und Markus Amstad, www.kreaho.ch
Sources:
Swiss Federal Institute for Forest, Snow and Landscape Research, WSL; Swiss Agency for the Environment, Forests and Landscape, BUWAL (eds.) 2001: Lothar. Der Orkan 1999. Ereignisanalyse. - Birmensdorf, Berne, Swiss Federal Institute for Forest, Snow and Land-scape Research, WSL, Swiss Agency for the Environment, Forests and Landscape, BUWAL. 365 p.
Ereigniskataster Nidwalden Unwetter August 2005, Ereignisdokumentation; Kanton Nidwal-den: Amt für Wald und Energie / Tiefbauamt; Stans 2006.
Glacier reports (1881-2002) “Die Gletscher der Schweizer Alpen”, Annuals of the Glaciologi-cal Commission of the Swiss Academy of Sciences (SCNAT), published by the Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich. No. 1-122, (http://glaziology.ethz.ch/swiss-glaciers/).
Homann, R: Das Klima ändert – auch in der Schweiz; Die wichtigsten Ergebnisse des dritten Wissensstandsberichts des IPCC aus der Sicht der Schweiz; 2002.
Hohmann, R: Klimaänderung und die Schweiz 2050; OcCC / ProClim; Vögeli AG Druckzen-trum, Langnau; 2007.
Summary for Policymakers; A Report of Working Group I of the Intergovernmental Panel on Climate Change (Iccp)
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