In an interdisciplinary project, scientists from the University of Innsbruck have examined climate change in terms of its regional impacts: using the Brixental as a case study, the team showed how rising temperatures and drought, combined with changes in forest management, can affect the hydrology of a Tyrolean mountain valley. The conclusion: maintaining managed alpine pastures could help mitigate some of the negative consequences of climate change.
When it comes to water supply, many residents of the Alpine region are rather spoiled. Water scarcity is largely unheard of in most areas. That this could change in the future is partly down to climate change, which is hitting the Alpine region particularly hard: rising temperatures and more frequent dry spells will put pressure on water availability. But what does that actually mean for a valley in concrete terms? And can anything be done about it? In the inter- and transdisciplinary project STELLA, funded by the Climate and Energy Fund, Markus Schermer from the Institute of Sociology and Ulrich Strasser from the Institute of Geography at the University of Innsbruck — along with their respective teams — spent three years looking for answers to these questions. As their study area, the researchers chose the heavily forested Brixental in Tyrol, more specifically the catchment area of the Brixentaler Ache, covering a surface area of 322 km². "Our research question was how climate change and different forest management strategies affect the water balance in mountain regions. We brought together our different areas of expertise and are really pleased that we managed to link social science and natural science perspectives in this project," say Schermer and Strasser. Another distinctive feature of the project is its close collaboration with the local population: experts, stakeholders, and forest managers were actively involved in the research process through surveys and workshops. "Without the knowledge and support of the people in the Brixental, the project wouldn't have been possible — the collaboration with the local community provided important input for the development of the hydrological models," Schermer emphasises.
Responding to climate change
Global climate scenarios are calculated on the basis of certain assumptions, which means regional characteristics can only be taken into account to a limited extent: "The dynamics of local processes, such as land use, can deviate from global scenarios. This depends on a range of natural and societal factors, such as topography or economic and political decisions. In mountain regions like Tyrol, where only 13 per cent of the land area can be used for settlements, industry, transport, and infrastructure, land use questions are of great importance in every respect. Changes there have an impact on how forests and alpine pastures are used," explains Schermer. The nature of land use change also influences the development of the water balance, adds Ulrich Strasser: "This touches on aspects such as water supply planning, the operation of hydropower plants, future irrigation, or the assessment of flood risk. There are decisions being made today that will influence how the expected changes in climate will play out regionally and locally in the future. We're not entirely at the mercy of climate change — our project identifies concrete room for action."
Merano vs. Bologna
Climate change will make the Brixental drier and warmer — to a lesser or greater degree depending on the climate scenario — but in any case clearly noticeable. "To make it more tangible, we compared the two climate scenarios we used with the current climate in other locations: the moderate scenario would mean a climate for the Brixental comparable to that of Merano, while the more extreme variant would be comparable to that of Bologna," says Strasser. To begin with, the team worked closely with local experts to develop possible socioeconomic development pathways for the region: how will land use change under certain conditions, and what factors influence this? This collaboration produced a range of socioeconomic scenarios covering a spectrum of possible responses to globalisation processes. "Questions of forest management, for example, are very closely linked to the management of alpine pastures and their continued maintenance," Schermer elaborates. The possible future developments were woven together into three typical storylines. The researchers then coupled these storylines with a moderate (Merano) and an extreme (Bologna) climate scenario. "Based on these future developments in land use and climate, tailored to the region, we carried out the hydrological model calculations that gave us the projected developments in the water balance of the Brixental," Strasser describes the approach.
The alpine pasture factor
The researchers' results show that, given the expected developments in the Brixental — in both climate scenarios — a further expansion of forest cover is likely to lead to even greater drought. "More forest area arises primarily when alpine pastures are abandoned: the land then becomes overgrown and new forest develops. But forest absorbs even more water from the system — and thus further amplifies the direct effects of climate change," says Strasser. This is a particularly crucial point for the Brixental, since many alpine pastures here already lie above the tree line today, which will in any case continue to shift upwards over the coming decades due to warming. "Cultivated, open alpine pasture areas could therefore play an important water retention function in the future. Forest can still protect people from flooding, but during low-rainfall periods it can also contribute to increased drought." How alpine pasture management is handled is ultimately a socio-political question. Schermer and Strasser see genuine potential for the concept they developed in STELLA — which allows them to look into the climate change future of a valley — to be applied to other mountain regions as well, provided the appropriate adaptations are made.
The research project STELLA (Storylines of coupled socio-economic and climate drivers for land use and their hydrological impacts in Alpine catchments) ran for three years with a funding amount of around 300,000 euros, focusing on the impacts of future climate and management changes in the Brixental. STELLA was led by Ulrich Strasser and Markus Schermer from the Institutes of Geography and Sociology respectively at the University of Innsbruck, and was carried out in collaboration with the Institute of Meteorology at BOKU Wien, the Climate Change Centre Austria CCCA, and ZAMG. It was funded through ACRP (Austrian Climate Research Program, 6th call) of the Austrian Climate and Energy Fund. Ingmar Höbarth, Managing Director of the Climate and Energy Fund, underlines the significance of the programme: "Climate change has serious and highly complex consequences for Austria. Within the framework of ACRP, these impacts are being systematically researched. This creates the basis for optimal adaptation to the changes taking place in Austria, and thus establishes essential decision-making foundations for securing our country's future."
Der Standard reported on the project: <link http: derstandard.at almen-koennten-folgen-des-klimawandels-abfedern external-link-new-window external link in new>Alpine pastures could cushion the consequences of climate change (22.11.2017)
