This study assesses the changes in the exceedances of joint extremes of temperature and precipitation quantiles for a number of sites in Europe. The combination of cool/dry, cool/wet, warm/dry and ...warm/wet modes reveals a systematic change at all locations investigated in the course of the 20th century, with significant declines in the frequency of occurrence of the “cold” modes and a sharp rise in that of the “warm” modes. The changing behavior of these four modes is also accompanied by changes in the particular conditions of temperature and precipitation associated with each mode; for example, the average amount of precipitation during cool/wet events decreases while that during warm/wet events increases, even though mean precipitation at most locations shows no significant trend. In a “greenhouse climate”, the “cool” modes are almost totally absent by 2100 whereas the warm/dry and warm/wet modes pursue the progression already observed in the 20th century.
This paper addresses a number of issues related to current and future climatic change and its impacts on mountain environments and economies, focusing on the "Mountain Regions" Chapter 13 of Agenda ...21, a basis document presented at the 1992 United Nations Conference on Environment and Development (UNCED) in Rio de Janeiro, and the International Year of the Mountains (IYM) 2002. The awareness that mountain regions are an important component of the earth's ecosystems, in terms of the resources and services that they provide to both mountain communities and lowland residents, has risen in the intervening decade. Based upon the themes outlined in the supporting documents for IYM, this paper will provide a succinct review of a number of sectors that warrant particular attention, according to IYM. These sectors include water resources, ecosystems and biological diversity, natural hazards, health issues, and tourism. A portfolio of research and policy options are discussed in the concluding section, as a summary of what the IYM and other concerned international networks consider to be the priority for mountain environmental protection, capacity building, and response strategies in the face of climatic change in the short to medium term future. PUBLICATION ABSTRACT
The 2003 heat wave that affected much of Europe from June to September bears a close resemblance to what many regional climate models are projecting for summers in the latter part of the 21st ...century. Model results suggest that under enhanced atmospheric greenhouse‐gas concentrations, summer temperatures are likely to increase by over 4°C on average, with a corresponding increase in the frequency of severe heat waves. Statistical features of the 2003 heat wave for the Swiss site of Basel are investigated and compared to both past, 20th century events and possible future extreme temperatures based on model simulations of climatic change. For many purposes, the 2003 event can be used as an analog of future summers in coming decades in climate impacts and policy studies.
Issue Title: Theme: Ecology of High Altitude Aquatic Systems in the Alps Meteorological and climatic processes in mountain regions play a key role in many environmental systems, in particular the ...quantity and quality of water that influences both aquatic ecosystems and economic systems often far beyond the boundaries of the mountains themselves. This paper will provide a general overview of some of the particular characteristics of mountain weather and climate, to highlight some of the unique atmospheric features that are associated with regions of complex topography. The second part of the paper will focus upon characteristics of climate and climatic change in the European Alps, a region with a wealth of high quality data that allows an assessment on how climate and dependent environmental systems have evolved in the course of the 20th century and how alpine climate may undergo further changes to "global warming" in the 21st century, as the atmosphere responds to increasing levels of greenhouse gases that are expected in coming decades.PUBLICATION ABSTRACT
Reliable estimates of future climate change in the Alps are relevant for large parts of the European society. At the same time, the complex Alpine region poses considerable challenges to climate ...models, which translate to uncertainties in the climate projections. Against this background, the present study reviews the state-of-knowledge about 21st century climate change in the Alps based on existing literature and additional analyses. In particular, it explicitly considers the reliability and uncertainty of climate projections.
Results show that besides Alpine temperatures, also precipitation, global radiation, relative humidity, and closely related impacts like floods, droughts, snow cover, and natural hazards will be affected by global warming.
Under the A1B emission scenario, about 0.25°C warming per decade until the mid of the 21st century and accelerated 0.36°C warming per decade in the second half of the century is expected. Warming will probably be associated with changes in the seasonality of precipitation, global radiation, and relative humidity, and more intense precipitation extremes and flooding potential in the colder part of the year. The conditions of currently record breaking warm or hot winter or summer seasons, respectively, may become normal at the end of the 21st century, and there is indication for droughts to become more severe in the future. Snow cover is expected to drastically decrease below 1500–2000m and natural hazards related to glacier and permafrost retreat are expected to become more frequent.
Such changes in climatic parameters and related quantities will have considerable impact on ecosystems and society and will challenge their adaptive capabilities.
•Warming is expected to accelerate throughout the 21st century in the Alpine region.•Seasonal shifts in precipitation, global radiation, and relative humidity are expected.•Precipitation and temperature extremes are expected to intensify.•Snow cover is expected to drastically decrease below 1500–2000m elevation.•Further changes related to droughts and natural hazards are expected.
This contribution provides an overview of the intricacies of mountain climates, particularly as they pertain to the European Alps. Examples will be given of issues that are related to climatic change ...as observed in the Alps during the course of the 20th century, and some of the physical mechanisms that may be responsible for those changes. The discussion will then focus on the problems related to assessing climatic change in regions of complex topography, the potential shifts in climate during the 21st century that the alpine region may be subjected to, and the associated climate-generated impacts on mountain environments.PUBLICATION ABSTRACT
This paper investigates the recent spate of record‐breaking warm seasons that have affected Switzerland in less than a decade and compares the seasonal statistics to those simulated for a ...“greenhouse‐gas” climate by the end of the 21st century. The peaks of minimum and maximum temperatures observed during some the record seasons enter well into the 25%–75% temperature quantile range for the scenario climate simulated by a set of regional climate models. The anomalously warm seasons allow a “preview” of conditions that may occur with greater frequency in the future. The use of current data as a form of proxy for the future enables an assessment of the possible impacts on the natural and socio‐economic environments, and can help in considering possible adaptation strategies to reduce some of the associated risks of climatic change.
Tree‐ring based reconstructions of 123 debris‐flow events in a case‐study area of the Swiss Alps since AD 1570 show enhanced activity during the wet periods (1864–1895) following the last LIA glacier ...advance and in the early decades of the 20th century. In contrast, comparably low activity can be observed since 1995, with only one event recorded. From the reconstructions and based on RCM simulations, there are indications that debris‐flow frequencies might continue to decrease in a future climate, as precipitation events are projected to occur less frequently in summer but become more common in spring or fall.
The intense convective storms that affected the Swiss Alps in late August 2005 resulted in what has been referred to as the “floods of the century” (i.e., the past 100 years). While exceptional in ...terms of their intensity, the 2005 storms do not appear to be anchored within any long‐term trends; there are no more intense storms today than a century ago. Despite uncertainties related to regional climate simulations of precipitation in complex terrain, projections for a “greenhouse climate” by 2100 suggest that extreme rainfall events may undergo a seasonal shift, with a rise in the number of episodes in the spring and autumn. Paradoxically, associated impacts may be reduced because the buffering effects of snowfall on runoff may be greater in future springs and autumns than during current summers, implying the 2005 floods are not necessarily an analog for such events by the end of the 21st century.
The European Alps are one region of the world where climate-driven changes are already perceptible, as exemplified by the general retreat of mountain glaciers over past decades. Temperatures have ...risen by up to 2
°C since 1900 particularly at high elevations, a rate that is roughly three times the global-average 20th century warming. Regional climate models suggest that by 2100, winters in Switzerland may warm by 3–5
°C and summers by 6–7
°C according to greenhouse-gas emissions scenarios, while precipitation is projected to increase in winter and sharply decrease in summer. The impacts of these levels of climatic change will affect both the natural environment and a number of economic activities. Alpine glaciers may lose between 50% and 90% of their current volume and the average snowline will rise by 150
m for each degree of warming. Hydrological systems will respond in quantity and seasonality to changing precipitation patterns and to the timing of snow-melt in the Alps, with a greater risk of flooding during the spring and droughts in summer and fall. The direct and indirect impacts of a warming climate will affect key economic sectors such as tourism, hydropower, agriculture and the insurance industry that will be confronted to more frequent natural disasters. This paper will thus provide an overview of the current state of knowledge on climatic change and its impacts on the Alpine world.
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