Preface

Continuous cycling of water in the atmosphere, surface waters, groundwaters and oceans is the basis of present life on Earth. Movement and retention of water around the world are intimately linked to the dynamics of the atmosphere and the global energy budget. Despite the low proportion (some 3%) of fresh waters overall, the fresh water reservoirs are of a crucial importance for biota and mankind. The surface waters within the Boreal Zone, with their small water volumes, naturally high contents of organic matter and long ice-cover period, are particularly susceptible to changes due to external loading induced by climate change. Even small changes in the external loading can severely effect the structure and function of the northern lacustrine ecosystems. Moreover, the Baltic Sea, the world’s largest brackish water basin, is also vulnerable to changes in loading of nutrients. There is clear evidence of the possible effect of climate change on waters in the Boreal Zone. The approaches used in different research programmes on climate change vary from palaeoecological methods reconstructing past climatic changes based on lake sediments and time series analysis of hydrological observations to dynamic modeling of hydrology, material fluxes and ecological responses of lakes, as well as to experimental studies of temperature effects on the rates of biological processes. These different approaches strongly complement each other. Without experimental work, the parameterization of the models would be very uncertain. On the other hand, modeling can reveal gaps in our knowledge and thus direct experimental work to the most relevant questions. The Boreal Environment Research presents highlights of the symposium on “Climate Change and Waters in the Boreal Zone”, held in Kuhmo, Finland, 21–24 November 1995, and organized by the Finnish Climate Change Research Programme (SILMU). The objectives of the Symposium were (i) to assess the current understanding of the processes controlling leaching of elements to surface waters in a changing climate, (ii) to assess the current understanding of the potential ecological effects in both fresh water and marine ecosystems due to climate change, (iii) to discuss the potential of presently available models for describing the dynamics of the impact on surface waters, and (iv) to discuss various scenarios produced by available predictive impact models for analyzing the climate change impact on surface waters. The main bulk of the results of the Symposium are included in the present issue. However, one paper (Regier et al.: “Likely responses to climatic change of fish associations in the laurentian Great Lakes Basin: concepts, methods and findings”) was already published in the former issue (Boreal Env. Res. 1: 1–16). Four papers accepted by the Boreal Environment Research will be published in the next issue: Gottschalk and Krasovskaia: “Climate change and river runoff in Scandinavia; approaches and problems”, Zhang et al.: “Variability of climate and ice conditions in the Bohai Sea, China”, Forsius et al.: “Impacts of climate change on material leaching from forests”, and Inkala et al.: “Modelling the effect of climate change on nutrient loading, temperature regime, and algal biomass in the Gulf of Finland”. The SILMU programme of the Academy of Finland is greatfully acknowledged for sponsoring the Symposium and the publication of the papers in the Boreal Environment Research.