A Change of Climate Provokes a Change of Paradigm: Taking Leave of Two Tacit Assumptions about Physical Lake Forcing



Physically, lakes have traditionally been viewed as individual systems forced by statistically stationary local weather. This view implies that the physical response of a lake to external physical forcing is unique and stationary. Recent recognition of the importance of large-scale climatic forcing in driving physical lake processes, combined with the realisation that this forcing is undergoing a long-term trend as a result of climate change, has led to a shift in this paradigm. The new physical paradigm views lakes more in terms of a local response to large-scale climatic forcing modulated by the addition of local noise. A strong climate signal leads to large-scale spatial coherence in the physical lake response, while the existence of trends in large-scale climatic forcing associated with climate change means that both the forcing and the physical lake response are statistically non-stationary. Thus increasing realisation of the importance of climate and climate change is invalidating the tacit assumptions of individuality and stationarity that underlie the old conceptual framework, resulting in its gradual abandonment in favour of a new paradigm based on the concepts of spatial coherence and temporal non-stationarity. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)