Battarbee et al. (2002) report the results of several studies that employed a variety of palaeolimnological techniques to reconstruct the temperature histories of seven remote mountain lakes in Europe over the past 200 years.  The lakes were all above the local timber line, their catchments were not affected by human disturbances, and most were far from anthropogenic pollution sources.  From their investigation, the authors learned that the seven sites experienced either general cooling or no trend in temperature during the nineteenth century.  During the twentieth century, on the other hand, the authors report that "all sites show a warming trend during the first few decades of the century," which peaks between 1930 and 1950.  Thereafter, all of the sites again depict cooling, as well as a steep warming over the last ten to twenty years of the record.  However, for only two of the seven sites does the final warming lead to warmer temperatures than those of the 1930s and 40s.  Of the remaining five sites, three of them end up being cooler than they were prior to mid-century, while two of them end up exhibiting the same temperature.

Similar findings were reported by Agusti-Panareda and Thompson (2002), who applied multiple regression analysis to twenty monthly lowland air temperature series for the period 1781-1997 AD and nine monthly upland air temperature series of at least 30 years duration to develop 216-year air temperature histories for eleven remote mountain lakes in Europe, including the seven lakes mentioned in the preceding paragraph.  What they found was that "during the period 1801-1900, the western European lakes show no significant trend whereas annual mean air temperatures at the eastern European lakes decrease significantly."  For the period 1901-1997, on the other hand, they note there is a warming trend "at all but the Fennoscandian lakes."

Even more interesting is what one learns when the 20 years from 1781-1801 are included in the analysis.  In terms of sliding decadal averages, four of the lakes depict net increases in air temperature over the 216-year period, three of them exhibit no net change, and four of them actually depict net cooling.  Hence, if close to a dozen European alpine and arctic lakes are no warmer now than they were during a short period of time at the "beginning of the end" of the Little Ice Age, when atmospheric CO2 concentrations were 90 ppm less than they are nowadays, there is little reason to presume that a similar period of modern warmth need be caused by the CO2 increase we have experienced in the interim.

In another study of both lakes and rivers in the Baltic region, Yoo and D'Odorico (2002) looked for evidence of temperature change among the dates of annual ice break-up at the termination of the ice season.  The results of their analysis demonstrated that a dramatic change in the dates of ice break-up (towards earlier thaw) occurred between the end of the 19th century and the beginning of the 20th century.  Describing these changes in more detail, Yoo and D'Odorico note that "the strongest long-term climatic changes nowadays observable in the Finnish cryophenological records started in the second half of the 19th century," which is also when the temperature record of Esper et al. (2002) shows the demise of the Little Ice Age to have begun in earnest.  In addition, they report that "the shift in the ice break-up dates terminated before [our italics] 1950," in harmony with our view of the temperature history of the globe, i.e., that there has been little net warming since the 1930s.

With respect to changes in the levels of lakes, Nicholson and Yin (2001) detected "two starkly contrasting climatic episodes" in a study of ten major African lakes since the late 1700s.  The first episode, which began sometime prior to 1800 and was characteristic of Little Ice Age conditions, was one of "drought and desiccation throughout Africa."  This arid episode, which was most extreme during the 1820s and 30s, was accompanied by extremely low lake levels.  As the authors describe it, "Lake Naivash was reduced to a puddle ... Lake Chad was desiccated ... Lake Malawi was so low that local inhabitants traversed dry land where a deep lake now resides ... Lake Rukwa [was] completely desiccated ... Lake Chilwa, at its southern end, was very low and nearby Lake Chiuta almost dried up."  Throughout this harsh period, "intense droughts were ubiquitous."  Some, in fact, were "long and severe enough to force the migration of peoples and create warfare among various tribes."

As the Little Ice Age's grip on the world began to loosen in the mid to latter part of the 1800s, however, things began to change for the better for most of the African continent as lake levels began to rise.  The authors report that "semi-arid regions of Mauritania and Mali experienced agricultural prosperity and abundant harvests; floods of the Niger and Senegal Rivers were continually high; and wheat was grown in and exported from the Niger Bend region."  Across the east-west extent of the northern Sahel, in fact, maps and geographical reports described "forests."

As the nineteenth century came to an end and the twentieth century began, there was a slight lowering of lake levels, but nothing like what had occurred a century earlier.  Then, in the latter half of the twentieth century, lake levels again began to rise, with the levels of some lakes eventually rivaling high-stands characteristic of the years of transition to the Modern Warm Period.

With respect to the Great Lakes of North America, Larson and Schaetzl (2001) present graphs of lake level fluctuations for the period 1915 to 1998, where it can be seen that the lowest levels occurred at about 1926 for Lake Superior, 1962 for Lake Huron-Michigan, 1933 for Lake Erie, and 1934 for Lake Ontario.  It is also noteworthy that the longest sustained period of high lake levels for all of the Great Lakes occurred over the last 30 years.  In addition, lake levels at the end of the record are essentially the same as those at the beginning of the record.  Hence, over what climate alarmists claim to be the century that has exhibited the greatest warming of the entire past millennium, which according to them should result in dire consequences for just about everything, there has been no net change in the water level of any of the Great Lakes.  In fact, over the past two decades of what they typically refer to as unprecedented warming, the four lakes have exhibited their greatest stability.

The above observations demonstrate that earth's lakes have suffered few ill effects from the warming that has transformed the Little Ice Age into the Modern Warm Period; and, by extension, they suggest that a little more warming would likely not be detrimental to them either.

References
Agusti-Panareda, A. and Thompson, R.  2002.  Reconstructing air temperature at eleven remote alpine and arctic lakes in Europe from 1781 to 1997 AD.  Journal of Paleolimnology 28: 7-23.

Battarbee, R.W., Grytnes, J.-A., Thompson, R., Appleby, P.G., Catalan, J., Korhola, A., Birks, H.J.B., Heegaard, E. and Lami, A.  2002.  Comparing palaeolimnological and instrumental evidence of climate change for remote mountain lakes over the last 200 years.  Journal of Paleolimnology 28: 161-179.

Esper, J., Cook, E.R. and Schweingruber, F.H.  2002.  Low-frequency signals in long tree-ring chronologies for reconstructing past temperature variability.  Science 295: 2250-2253.

Larson, G. and Schaetzl, R.  2001.  Origin and evolution of the Great Lakes.  Journal of Great Lakes Research 27: 518-546.

Nicholson, S.E. and Yin, X.  2001.  Rainfall conditions in equatorial East Africa during the Nineteenth Century as inferred from the record of Lake Victoria.  Climatic Change 48: 387-398.

Yoo, JC. and D'Odorico, P.  2002.  Trends and fluctuations in the dates of ice break-up of lakes and rivers in Northern Europe: the effect of the North Atlantic Oscillation.  Journal of Hydrology 268: 100-112.