Climate

Long-term climatic conditions

The Berchtesgaden Alps are located in a climatic transition area. The prevailing regional climate is influenced by the oceanic climate of the Atlantic and the continental climate of Europe and East Asia. In the National Park, the climate is characterized by a particularly high vertical, horizontal and temporal variability. The considerable altitude difference of over 2,000 m and the terrain relief are decisive for the fact that the climatic conditions change very strongly in a small area.

In addition to the altitude, exposure and slope as well as the windward and leeward effects of the mountain ranges significantly influence the climatically relevant factors such as temperature, precipitation, evaporation, wind currents, and radiation conditions. In addition, there are seasonally variable weather situations typical of the mountains, such as pronounced mountain and valley wind systems, inversions, foehn weather, congestion and rapid weather changes. The climate of the national park is determined by the long-term average of these diverse weather conditions consisting of diurnal, seasonal and small-scale fluctuations.

 

Meteorological readings yesterday and today

The mean annual temperatures range from +7 °C at Königssee to below -2 °C in the summit regions of Watzmann and Hochkalter. Accordingly, the vegetation period is shortened from 160 days in the valley areas to less than 60 days at the highest altitudes. Due to its location on the northern edge of the Alps, the area is characterized by high precipitation overall, which manifests itself in often persistent rainfall in summer and long-lasting snow cover in winter. Mean annual precipitation increases with terrain elevation from 1,500 mm to 2,800 mm. The duration of snow cover days in the valley regions around 600 m a.s.l. is about 110 days, at 1,500 m a.s.l. the snow cover days increase to 200 to 215 days, and above 2,000 m a.s.l. about 270 days are reached. The maximum snow depths are reached below 1,000 m a.s.l. in February, at higher elevations in March. The average snow depths vary between 50 cm in the lowest valley locations and three to five meters in the higher elevations of the national park.

Due to the rapid change of the climate on the global as well as on the regional level, these data will no longer be valid in the future. While the temperature at the earth's surface increased globally by about +0.6 °C in the last century, an approximately twice as strong warming of about +1.1 °C was observed in the Alps in the same period (Smiatek et al. 2009). This spatial difference in temperature development can also be observed in the recent past: The temperature increase over the last 10 years has been quantified globally at about +0.4 °C (NOAA, 2018), but in the Berchtesgaden National Park much higher increases have been recorded over the same period - at Watzmanngrat an increase of +0.98 °C, at Blaueisgletscher even +3.7 °C (Nationalparkverwaltung Berchtesgaden, 2017). Especially at Blaueis, it becomes clear that climate changes in the mountains can have a much more extreme effect than in non-mountain regions of the same climate zone. The enhanced temperature increase in alpine regions is due to different processes, including e.g. the snow-albedo feedback effect (Gobiet et al. 2013). The smaller the extent of the summer snow area, the more the darker, heating rock and debris surfaces enhance the melting effect in the still snow-covered surroundings.

 

Expected climate development

Climate change over long periods of time (e.g. ice ages) and abrupt climate changes (e.g. volcanic eruptions) are natural influences over millions of years of the earth's history. However, the global warming observed since industrialization is primarily caused by humans. This anthropogenic climate change is proceeding very rapidly and is not complete.

By calculating scenarios, scientists attempt to forecast future developments on the basis of models. The scenarios of the IPCC-AR5 (Intergovernmental Panel on Climate Change - Fifth Assessment Report) show for different framework conditions (so-called Representative Concentration Pathways - RCP 2.6-8.5) that a further global temperature increase of 1 °C to 3.7 °C on average is foreseeable by the year 2100 (IPCC 2014).

In a research collaboration (Kunstmann et al. 2019) to regionalize these scenarios, the following developments were modeled for the near future until 2050 (under the "temperate conditions" of RCP 4.5): For the Berchtesgaden National Park, the simulations result in an increase of the annual average temperature between +0.95 °C and +1.03 °C (for Bavaria on average +0.96 °C). This increase is particularly pronounced in spring and significantly lower in the autumn months (spring +1.5 °C / summer +1.0 °C / autumn +0.5 °C / winter +1.3 °C). In the case of precipitation, an increase in the annual totals of between +104 mm and +274 mm is shown for the national park area (for Bavaria on average: +76 mm). However, this increase in annual precipitation results almost exclusively from an increase in winter and autumn precipitation, while the precipitation amounts in summer and spring remain almost unchanged. Due to the simultaneous rise in temperatures, however, less precipitation falls in the form of snow. Both lead to a significant decrease in snow cover duration of -13 days in the area, this mainly due to a reduced snow cover duration in spring and especially in the middle altitudes (800 - 1300 m a.s.l.).

The changed dynamics of temperature, precipitation and snow cover will affect the water balance with consequences that are not yet fully foreseeable. This is especially true since the already large heterogeneity of precipitation distribution in the national park, as in high mountain areas in general, will be further intensified by extreme events. According to current estimates, it can be assumed that snowmelt will occur and be completed even earlier in the future. The mass loss of snowfields and firn ice surfaces, which has been observed for decades, has long been further evidence of this. Since the water reservoirs bound in the form of snow will be available for less time in the summer half-year, further chains of effects can be expected. Increasing the knowledge for these interrelationships is the subject of national park research.

 

Consequences of the expected climate development

Based on these scenarios, sooner or later changes in both abiotic living conditions and biotic communities and their diverse interactions are to be expected. Especially the vegetation period as one of the key elements of ecosystem dynamics is subject to significant changes. In the period from 1951 to 2015, the linear trend of the measured values shows an extension of the vegetation period by about 15 days. During the last 60 years, this corresponds to an average extension of about one day in each four-year period (BMU 2017). This is the result of an earlier onset of spring and a later onset of winter and will lead over time to a shift of the previous vegetation zones horizontally towards the poles as well as vertically to higher altitudes. In the Berchtesgaden National Park, a variety of change processes can be assumed due to the large altitudinal gradient.

This is where the monitoring programs and research questions of the national park come in. In addition to an automated climate measurement network, which documents abiotic trend developments in high spatial and temporal measurement density, there are long-term observations of flora and fauna, some of which show clear effects of climate change. These include, for example, the increase in species numbers in the summit vegetation over a period of 26 years, which cannot be attributed to eutrophication effects (Kudernatsch et al. 2016, Fegg et al. 2012), or the earlier onset of swarming of bark beetles in spring, which led to an advance of the annual monitoring by two weeks in 2010 after 25 years of observation. In other areas, no significant climate change signals have yet been found, such as in the 25-year spring monitoring of the National Park . A response of springs is expected mainly in terms of pouring behavior and water temperature, which may be delayed due to the (still) existing buffer effect of snow cover (Lichtenwöhrer et al. 2019a).