of climate change on water resources – a case study of the Great Lakes of North America ” by

The analysis of the behaviours of climatic variables is an important issue today, espe-cially when trying to detect the presence of climate change. The literature about this subject counts a lot of contributions. Unfortunately the results are not always clearly presented. In some cases the distinction between presence and absence of trend is very dubious and therefore it is extremely important to introduce proper statistical assumptions that should be thoroughly verified. S1614 The referees of this paper pointed out very important remarks that are all to be taken into account when revising the manuscript. The issue of uncertainty is particularly delicate and important. I would like to add a personal observation. I believe the paper should explain in detail how the statistical significance of the slope of the regression lines was evaluated. Was the correlation in the analysed records taken into account? It is well known that in the presence of correlation the confidence limits of the slope of the regression line ma