The North-Watch project ran between 2009-2012 and was funded by the Leverhulme Trust. The Project is lead by Professor Doerthe Tetzlaff and involved collaborators from Scotland, Canada, Sweden, Switzerland and USA


Aims

This was a highly interdisciplinary project which examined long-term data from experimental catchments spanning different hydro-climatic zones within the northern region in the USA, Canada, Scotland and Sweden to assess the integrated physical, chemical and biological response of northern watershed ecosystems to climatic change. This was achieved through inter-catchment comparison by a team of leading international scientists affiliated with seven other universities in the USA, Canada, Sweden and Switzerland. The work was intended to examine some of the variable responses to climate change observed at different experimental sites in the northern temperate zone. This also provided a basis for extrapolating understanding to larger watersheds where climate change impacts are of more relevance to environmental managers.

The specific questions that the project aimed to answer were:

  1. What aspects of climate are the main drivers of the hydrological regime and are these showing clear, directional change in response to global warming?
  2. How is catchment biogeochemistry being affected by any climatic and hydrological change and is water quality changing significantly as a result?
  3. To what degree is there any detectable ecological response to such changes in the quantity and quality of stream flow?
  4. How can recent empirical data be integrated with models to provide a learning framework for predicting the likely integrated response of water resources to climate change?
  5. To what extent does the synthesis of existing data show a regionalised response to climate change?

As the answers to these seemingly simple questions were likely to be complex with any impacts to date likely to be subtle and difficult to detect, a major focus of the project was to compare different methods of data analysis in order to develop standardised approaches, identify further issues, and develop well-defined and directed future investigations. We aimed to achieve these goals through five international workshops, each focusing on one of the questions outlined above

 

Background

There is now compelling evidence that global warming and associated climate change are impacting water resources in many parts of the world. Managing the societal consequences of this is one of the 21st Century’s major challenges to the prosperity and security of the international community. In few places will the changes and challenges be greater than in the boreal / subarctic region (defined broadly as the higher mid-latitudes) of the northern hemisphere. In this circumpolar, transitional climatic zone, slight temperature differences determine whether precipitation falls as rain or snow, and the degree to which winter snow packs accumulate and the rate at which they subsequently melt.

The potential consequences for water resources and aquatic ecosystems are profound. Increasing temperatures in this region have already been implicated in changes in the nature, intensity and seasonal distribution of precipitation, which in turn has been shown to impact the flow regimes of rivers affecting the frequency and magnitude of floods and the severity of droughts. In turn, climate and the flow regime of such rivers have major influences on biogeochemical processes and water quality. For example, high flows are often associated with the flux of dissolved organic carbon (DOC) from the organic soils that dominate many northern regions. Increased decomposition of peaty soils resulting from higher temperatures has been shown to increase the carbon flux in streams, with implications for the chemistry of ocean waters, the global carbon cycle and climate. Whilst such changes in the quantity and quality of water resources have obvious implications for society (flood and drought management, drinking water treatment, etc.), they will also affect the structure and function of aquatic ecosystems. These often provide ecosystem services (e.g. fisheries, biodiversity, etc.) upon which societies are also highly dependent.

Predicting the integrated consequences of climate change on the physical, chemical and biological characteristics of water resources in individual locations is an extremely difficult area of interdisciplinary environmental science. Extrapolating such predictions to other regions is even more problematic. Fortunately, in many areas, research catchments have been established that provide our best longer-term data sets that encompass integrated measurement of the linkages between the climate, hydrology, biogeochemistry and ecology of river systems and how these are being affected by climatic change.