Largest Lakes of Russia under Global Warming

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1 Largest Lakes of Russia under Global Warming LEMESHKO Natalia State Hydrological Institute, Saint-Petersburg, 2-nd Liniya, 23, Russia Abstract: Climate change is expected to affect lakes which are the important freshwater resource. Eight largest lakes contain about 96% of water resources of all lakes over Russia territory. Modern environmental and climate change, caused by natural and man-made factors, drives to important changes in hydrological regime оf lakes. However the response of the individual lakes to these changes depends on the magnitude and nature of regional climate change. The lakes level is a reliable moisture integrator, reflecting water resource within a vast territory, and that is why it can be used as indicator of modern climate change. Lakes also impact on hydrometeorological characteristics of coastal areas, which changes should have both positive and negative consequences of different scale for ecological state and humanity. Water balance, lake level, thermal characteristics, ice events and ice thickness have been studied for largest Russian Lakes Baikal, Ladoga, Onega, Ilmen, Pskovsko-Chudskoe, Chany, Taimyr and Khanka based on the data of observation. A steady-state hydrological model has been developed for evaluation of changes in water balance of lakes with the progress of global warming. The paleoclimatic reconstruction for global warming on 2ºС has been used as empirical scenario. This scale of climate change corresponds to warm epoch of the past, considered as analog of future climate: the Last Interglacial-Eem (125 KA B.P.). The combined assessment of regional peculiarities for the period of hydrometric observations with the paleoclimatic scenario makes it possible to decrease existing sufficient uncertainty in the forecast of the hydrological regime of lakes. Keywords: Climate change, Ice, Global warming, Response of lake to climate change, Paleoclimate, Scenario, Water level, Water temperature water and they are the crucial factors of human life and life quality. It is the problem of fresh water support that should be placed under unceasing control of scientific community, ecologists and human society. The lakes of Russia are an important source of fresh water and therefore there is no way to overestimate their significance for population and economy. Lakes are also among the most vulnerable aquatic ecosystems. There are 34 lakes with water surface exceeding 250 km 2 in Russia. There are only five saline and braсkish lakes among them. Anthropogenic influences on nature, building waterside structures and regulating river flows as well as climate changes in the 20 th century have resulted in considerable changes of lake regime including water level, water temperature and ice phenomena. The following negative factors such as pollution, lake eutrophication, decrease of commercial fisheries have become the reality of nowadays life. These processes need to be thoroughly studied because ecological state crisis can become irreversible. The issue of change of lakes hydrology under the impact of anthropogenic pressure and climate changes makes the subject of scientific researches and discussions for scientists of different fields of science including hydrologists, climatologists and hydrobiologists. The significant uncertainty of water resources forecasts and anthropogenic impact on lake basins and in particular contradictory forecasts for temperature, precipitation, river runoff for large areas, does not allow us to have reliable long-term predictions. Adoption of different scenarios for the future climate, including those ones based on paleoclimatic reconstructions, enables us to enlarge our conception of probable and extreme changes in lake regimes. Paleoclimate and paleohydrological history of lakes can provide us with plenty of such extreme evidences. 1. Introduction The alternative sources of energy and daylight have been discovered during the social life. However, there is no substitute for fresh water to maintain life activity for mankind. Recent scientific studies indicate that the water-related hazards make up 69% of ecological disasters [ 1 ]. Among these disasters, droughts make the greatest number (52%) and floods represent 11%. Thus, rivers and lakes are the main sources of available fresh 2. Lakes of Russia Among lakes with water surface more than 1 km 2 over Russia there are near 21 thousand lakes with water surface more that 100 km 2 and 8 largest lakes with water surface larger than 1000 km 2. Total water surface of the large lakes makes up about km 2 and it is comparable with total square of small lakes (from 1 to 10 km 2 ). [ 2 ]. About 96% of total fresh water of all lakes over Russia territory is contained in eight

2 largest lakes with water surface more than 1000 km 2 and km 3 (95,2%) of fresh water of this volume gives Lake Baikal. Characteristics of the largest Russian lakes are shown in Tab.1 based on the data [ 2 ]. Ladoga, Onega, Chudsko-Pskovskoe and Ilmen are fresh water lakes of European territory of Russia (ETR). The world s deepest and oldest Lake Baikal is among four great lakes of the Asian part of Russia and other lakes are Lakes Khanka, Taimyr and closed brackishwater Lake Chany. 2. Current climate changes on the territory of Russia Climate changes are the part of global environment changes and become apparent on the different levels from global to local (landscape belts, countries, river s and lake s basins). Lakes are among the most vulnerable environmental objects exposed to climate change. Lake regime is determined by many interconnected permanent and transient factors and also climatic ones such as: precipitation and river runoff, air temperature and snow cover. Since the late 19 th century the mean annual air temperature has increased by about 1.29ºС for the Russian territory that surpasses the global annual air temperature increase. Recent years the tendency towards warming has grown significantly and in the period of the mean annual surface air temperature increased by 0.4 С [ 3 ] has manifested to be the warmest year followed by 1995 and 2005 for Russia. Anomalies of mean air temperatures were positive for all the seasons, more pronounced in the winter-spring period (trend equals to 0.3 С/10 years), less in the summer-autumn. In the autumn period, even, some cooling has taken place in western ETR up to 2000 [ 4,5 ]. Mean annual temperature has increased rather unevenly over all territory. Tab. 1 The largest lakes of Russia [ 2 ] Lake Area, km 2 Maximal depth, Volume Watershed Water surface m km 3 Baikal Ladoga Onega Taimyr Khanka 20100* 4190** ** 3030** Chudsko * 3555* Pskovskoe 27917** 1990** Chany Ilmen * Total area; **Area belonging to Russia Warming was more evident in European Russia and Eastern Siberia with the highest growth of temperature. Warming was most intensive in Central Siberian Plateau and north-west of European Russia during winter-spring period and in Transbaikalia and west of European Russia in summer. Precipitation changes have more complicated space-time structure than temperatures due to their variability. Changes in precipitation totals have not showed any clear tendency for last decades over the area under study. It was found that annual precipitation averaged over Russia increased (7.2 mm/10 years) for the period Since 1995 less annual precipitation has been registered only for the years of 1996, 1999, 2003, and 2005 as compared to the average annual precipitation for The most essential changes comprise an increase in spring precipitation (16.8 mm/10 years) in the western and north-eastern regions of Siberia and in the European part of Russia. However, a decrease in winter precipitation was observed in the north-eastern regions of Siberia, the northern part of Khabarovsk Land and the eastern part of the Chukchi autonomous region [ 3,6 ]. There has been observed the most considerable increase of spring precipitation in a season chart for the last 30 years with 1.4 mm/month for 10 years. Sustainable precipitation increase has been pronounced only in Western Siberia and Transbaikalia. The greatest trend accounts for 2 mm/month per 10 years for Western Siberia, but it explains less than 20% of interannual variation. Precipitation is increasing mostly in winter, spring and autumn and it is decreasing during summer in European part of Russia. The decade appears to be the most humid for ETR, which corresponds to the 1920s conditions [ 5 ]. An empirical data shows that winter has become milder as the number of days with extremely low temperature decreased and coldest month moves from January to February, December and even to November [ 7 ]. The minimum air temperature increased by С per 10 years in the most part of Russia. The number of thaw days increased in cold period as a result of the growth of number of days (2 days per 10 years) with abnormally high air temperature in Consequently the number of frosty days has been decreased of 4-5 days per 10 years for the same period [ 8 ]. Considerable rise of air temperature comes to earlier dates of a persistent transition of air temperature through 0, 5 and 10 C in spring up to 7-10 days and increasing of warm season duration in the North-West and Central Russia Regions. On the other hand, there is an expansion of frost free period to the north. 3. Hydrological regime of lakes under the impact of global warming The above mentioned tendencies of current climate change, to some extent, should explain the trends in mean annual lake level time series as integral index of water and climate resources fluctuations. Variations in

3 air temperature, precipitation, and other meteorological parameters cause direct changes in water balance, lake level, thermal characteristics, ice events and ice thickness, as well as hydrochemical and hydrobiological regimes, and entire lakes ecosystem. However the response of the individual lakes and lake basins to these changes will depend on the magnitude and nature of regional climate change including peculiarities of the atmospheric circulation manifestation, and the specific geomorphologic characteristics of lakes [ 9 ] Changes in water level The lakes level is a reliable moisture integrator, reflecting water resource within a vast territory, and that is why it can be used as indicator of modern climate change. Modern environmental and climate change, caused by natural and man-made factors, drives to important changes in hydrological regime оf lakes. Lakes also impact on hydrometeorological characteristics of coastal areas, which changes should have both positive and negative consequences of different scale for ecological state and humanity. The instrumental observations of lake water level started in Russia in the middle of 19 th century, the earliest ones relate to Lake Ladoga in Those largest Russian lakes as Baikal, Onega, Ilmen, Chudsko- Pskovskoe and Khanka have less long time-series observations: Lake Onega since 1884; Lake Baikal - since 1901; Lake Chudsko-Pskovsko since 1907; Lake Ilmen since The time-series are even shorter for the other lakes: Lake Khanka since 1932; Lake Chany - since 1934; Taimyr since The analysis of lake water level under climate changes during recent decades was carried out on the basis of comparison of changes during observations [ 10 ]. Three of studied lakes show negative trends (Ladoga, Onega and Chudsko-Pskovskoe) and Lake Chany manifests a positive one [ 11 ]. The analysis of changes in mean annual water level of Lake Ladoga revealed statistically significant negative trend for 150 year observation period, and it accounts for 4cm/10years. The rate in water level decrease has accelerated for the recent 25 years and it makes up 17cm/10years for years. Fig. 1 shows the long-term changes of mean annual level of Ladoga for the period of observation (a) and for the last 25 years (b). Negative trend by 4 cm for 10 year period (statistically significant at 95 % level) gave way to the trend of 17 cm for 10 years in Water level regime of Lake Onega the second large lake of Europe developed in natural conditions before Verhne-Svirskaya Hydropower Station startup in Water level changes of Lake Onega differ drastically from those of Lake Ladoga within interdecadal period. Negative water level trend of the lake for the period changed into the positive trend of 4 cm/10 years presenting background for the lake water level decreasing of 10 cm/10 years during the last 25 years. Lake Chudsko-Pskovskoe is ranked the third large lake in Europe in terms of surface. The water level within observation period manifested to have statistically significant negative trend of 6 cm/10 years. The trend has increased since 1980 and makes up 16 cm/10 years for period. The catchment of Lake Ladoga comprises the forth largest European Russia s Lake Ilmen. It differs considerably from other large lakes by its level regime. Lake Ilmen s uniqueness consists in considerable amplitude of water level variation. It is second to none in the country as its amplitude accounts for 7.5m. The watershed area of Lake Ilmen is 60 times large as its water surface (the same index of Lake Ladoga makes up 15 times, the one of Lake Onega does 5 times). Maximum mean annual water level was registered in 1953 (20.3m BS) and in 1990 (19.65m BS). Minimum water level of the lake precedes the year of the most minimal level of Ladoga in 1940 and equals to 17.46m BS. After 1939 this level was seen only in 1972 and The lake regime peculiarities don t make it possible to discover a stable trend in the mean annual water level change of Lake Ilmen within the observation period or the period of Mean annual level of Lake Baikal has no statistically significant trend within natural regime ( ) nor within the last 25 years. This feature makes it different from the other large Lakes Ladoga and Onega year period is marked by the Baikal water level decrease from its high in 1964 to its low level in Water level of 1964 was maximal for all time-series. The low water levels of 1980, 1981, 1997 and 2003 were 80cm higher than minimums registered in 1920-s as water level is artificially regulated. The level of Lake Chany situated in steppe area is exposed to considerable variations (up to 5 m). Total a) b) level, cm level, cm year years Fig. 1 Water level of Lake Ladoga and linear trends for the period of observations (a) and for the (b).

4 level increase equals to 2 m within the period from the early 1900 to A decrease of 3m was registered for years. Then took place a sharp raise of the lake water level equal to 198 cm within which gave place to decrease of 184cm by Further decrease of water level was stopped by Yudinsky Stretch abjunction. A statistically significant positive trend equal to 30cm/10years was observed within Water balance The most complete study of mean annual water balance of the largest Russian lakes and its variations within the last decades was carried out by T.P. Gronskaya and published in monograph Water resources of Russia and their use [ 12 ]. The income part of water balance of the largest Russian lakes mainly consists of water inflow by rivers (205 km 3 /year) and precipitation to water surface (37.8 km 3 ). The outcome part includes river outflow and evaporation (32.6 km 3 /year). For endorheic Lake Chany the income to lake is spent to evaporation only. Patterns of water balance differ significantly for each specific lake. For example, the inflow is the main part of income of Lake Ilmen (96.3%) but it gives smallest part of income for the Lake Chany. The most part of income to closed lakes Chany and Khanka gives precipitation (60% and 55% respectively). The outflow makes up almost the entire outcome for the large lakes except closed Lake Chany with evaporation making up 100% of its balance outcome. Assessment of climate change influence on water balance of the largest Russian lakes was made for 7 lakes (except Taimyr). Comparison of mean many-year values of water balance components for the period before 1980 and for the showed a growth of less than 10% of mean annual water balance components for Lakes Ladoga, Onega, Khanka, Chany. More significant changes were characteristic for Lakes Baikal, Ilmen, Chudsko-Pskovskoe. Increase in inflow (14%), in precipitation and evaporation from water surface (up to 50%) was registered during the last 25 years for Lake Baikal as compared with the period before hydroelectric dam building ( ). Higher water resources of rivers have come to increasing inflow of Lakes Ilmen and Chudsko-Pskovskoe for the recent years. However, air temperature growth and lake water temperature raise caused an increase in evaporation only of Lake Ilmen. The evaporation assessment of Lake Chudsko- Pskovskoe would need an additional study. 3.3 Water temperature The following characteristics of surface water temperature regime of lakes were studied: mean monthly and maximal water temperature, dates of persistent transition of water temperature through 4 C and 10 C in spring and autumn under climate change. Study shows the largest increase of mean monthly water temperature in the Lakes Chany and Baikal during June and July (0.5 C/10 years) and about 0.3 C/10years in the lakes of European Russia. Maximal water temperature did not change considerably for the Asian lakes (less than 0.3 C) and did not change in European lakes. In average dates of transition of water temperature through 4 C and 10 C in spring move of 5-7 days to earlier dates. In autumn these dates move to later ones for Lakes Baikal, Chany and Khanka and move to earlier ones for Lakes Onega and Ladoga as some cooling was observed in autumn partly in the territory of European Russia Ice phenomena and ice thickness Climate change is having an increasing impact on the characteristics of ice cover on the lakes. This has important implications for aquatic ecosystems sustainable development and activities on lakes [ 13 ]. The study was based on the data of ice observations on the largest lakes of Russia. Observation period varies within years for Lakes Ladoga and Onega, respectively, to 40 years for the Lake Taimyr. The database of ice observations on the Russian Hydrometeorologic Service (Roshydromet) network has been established at the State Hydrological Institute. This database includes data on such ice phenomena as the date of ice events beginning, ice-on data, date of ice cover break-up, date of ice-off, duration of ice cover period, ice cover thickness. Ice-on dates were defined as the date when 100 % of lake area within a visible sector of gauge was covered with ice, then followed by a permanent ice cover period for winter of previous and next years. Ice cover break-up dates were defined as the date when the first signs of ice cover destruction appear. Ice-off dates were defined when lake area within a visible sector of gauge was free of all ice in spring. Ice cover duration corresponds to a number of days when 100 % of lake area within a visible sector of gauge was covered with ice. Maximal ice cover thickness was defined using each ten days measurement of ice cover thickness from the date of ice cover on. Temporal trends and anomalies have been discovered in the ice events, ice cover duration and maximal ice thickness during on the background of a long-term variability of the study characteristics for Lakes Ladoga, Onega, Baikal and Taimyr [ 14,15 ] All studied lakes show the tendencies to earlier date of ice cover break-up and decrease in duration of ice cover on lakes (Tab.2). Maximal ice cover thickness had the most pronounced response to climate warming in winter time during the last decades of 20 th century. All studied lakes exhibited the tendency to decrease of maximal ice cover thickness after 1980 [ 16 ].

5 4. Hydrological regime of lakes with global warming by 2 C The further development of global warming can lead to growth of average annual global air temperature on 1ºС in the first decade of 21 century, and on 2ºС by 2025 [ 17,18 ]. Close relationship between the physical processes in the atmosphere and on the earth surface causes not only temperature changes, but also the changes in other components of environment such as hydrological regime of lakes. In this connection, the investigations of possible change in the hydrological regime of lakes with the global warming are very important Method and data A stationary hydrological model has been developed to evaluate changes in river inflow and in water level of the largest lakes with the progress of global warming. The model is based on the heat-water balance method and on the paleoclimatic scenario of global warming on 2 С [ 19 ]. The calculations are made using the data on deviation of annual precipitation, winter and summer air temperature for the Last Interglacial (125 KA B.P.) from the up-to-day ones. This period, when global air temperature was 2 C higher than modern one, is considered as the analogue of future climate to a certain extent [ 20,21 ]. The method is universal as it is based on empirical data of different climate conditions and joint solution of heat and water balance equations, together with two empirical dependencies for evaluation of evaporation and runoff Water level The results of calculation exhibit (Tab.3) the individual peculiarities of lake s response to warming by 2 C: changes in annual river inflow to lakes, evaporation from lakes basins and from water are different for different lakes. The most significant changes both in river inflow and in evaporation should be characteristic for Lake Taimyr located in tundra zone, less pronounced for Lake Khanka located on the Pacific slope of the Eurasia [ 22 ]. To estimate lakes level change of Ladoga and Onega, additional assumptions based on historical analogy have been used: the outflow of lake is Tab. 2 Trends in time series of ice phenomena and ice thickness for Lake Ice cover Maximal ice duration, thickness, cm days Ladoga -6-3 Onega -2-7 Ilmen Baikal considered as either equal to average long-term and/ or equal to maximal outflow for the period of observation. Calculations have shown the level of Lake Ladoga should rise of 1 m and Onega Lake level would be higher of 0.5 m if outflow equals mean annual. At the maximal value of outflow from the lakes the level of Ladoga can lower of 0.5 m, and Onega - of 0.6 m Changes of lake s ice cover at 2 C warming The historical analogue approach was used to examine the response of the study lakes to recorded extremes in the weather. The ice events and ice cover thickness of the extreme years (when mean for the cold period air temperature was 2 C higher than normal for the recording period for each lake catchment) were employed for these purposes. Tab. 4 shows that at 2 C warming the most dramatic changes should occur in the largest European Lake Ladoga, where there ll be no stable ice cover. On the other water bodies the shift to later ice-on dates will be from 25 days (Lake Taimyr) to 35 days (Lake Onega), and to earlier ice cover break-up dates: from 5 days (Lake Onega) to 15 days (Lake Taimyr). 5. Conclusion Large lakes are very sensitive natural indicators reflecting both long-term and short-term climate changes. Changes of hydrological regime of lakes can have both positive and negative consequences for economic and social life. Decrease of lakes level, as a rule, has negative after-effects. First of all it is connected with deterioration of water supply. High lakes level can have both positive and negative consequences. Thus, it is favorable for water supply of the population, an agriculture, water-power engineering, etc. But it can result in flooding settlements and agricultural lands, to bogging and degradation of a soil cover [ 23 ]. Tab. 3 Changes in climatic and hydrological parameters of lake basin with global warming by 2 C Lake Baikal Onega& Taimyr Khanka Ladoga Air temperature and precipitation deviations according to scenario Summer air temperature, C Winter air temperature, C ,3 Annual precipitation, mm Calculation Annual runoff, (% from mean annual) Evaporation, (% from mean annual) Potential evaporation from water surface, (% from mean annual)

6 Lake name Tab. 4 Changes in lakes ice characteristics by 2 Cwarming in their catchments Ice-on (days to mean date) Ice breakup (days to mean date) The estimates show that most significant changes of lakes hydrological regime would occur in the High Latitudes. It is very important as Global Climate Models and paleoclimatic reconstructions suggest that an anthropogenic global warming should manifest itself most strongly in the High Latitudes and northern lakes may be very vulnerable to global climate change. Ice phenomena on the largest lakes of Russia are very sensitive to the global warming. The most pronounced changes are characteristic for the maximal ice cover thickness: all water bodies show its decrease while half of them exhibits statistically significant trend during last decades of the 20 th century. The future global warming by 2 0 C should influence dramatically on all ice characteristics of lakes. The most striking effect will be observed on the largest lake of the Europe (Lake Ladoga) and on Lake Taimyr. Therefore we shouldn t ignore the up-to-date and expected changes in the hydrological regime of inland water bodies as one of the most sufficient elements of the sustainable development of human society. Methods of paleogeography usually use the lakes as the reliable indicators of changes in natural ecosystem, temperature and moisture regime for different epochs in the past. Now we have made an approach to use paleoclimatic reconstruction and historical time series to predict the hydrological regime of lakes with expected changes of climate. References Ice cover duration (days to mean) Maximal ice cover thickness (cm to mean) Onega Ladoga No stable ice cover Taimyr [1] Hydrometeorological disaster risk reduction: working together. Bulletin WMO. Vol.53, No 1, January pp [2] Water resources of Russia and their use. Ed. by I.A.Shiklomanov. St.Petersburg: State Hydrological Institute p. [3] Assessment report on climate change and its consequences in Russian Federation. General Summary (2008): Moscow. Roshydromet, p. [4] Efimova N.A., Zhilsona E.I., Lemeshko N.A. and Strokina L.A Comparative assessment of climate changes in and paleoclimatic analoques of global warming. Meteorology and Hydrology, N 8, pp [5] Lemeshko N.A., Speranskaya N.A. The peculiarities of moisture regime of European territory of Russia with climate change. Present situation in hydrometeorology. Asterion, 2006, 38-54, (in Russian). [6] Bulygina O.N., Korshunova N.N., Razuvaev V.N. Climatic conditions over the territory of Russia [7] Lemeshko N. A., Nikolaev M. V., Uskov I. B.. Adaptation of agriculture to climate change. Lema, p. (in Russian). [8] Neushkin A.I., Sanina A.T., Ivanova T.B. Dangerous natural hydrometeorological phenomenon in federal districts of European part of Russia. Obninsk, (2008):312, (in Russian). [9] Gronskaya T. P., Lemeshko N. A., Arvola L., Jarvinen M. Lakes of European Russia and Finland as Indicators of Climate Change. World Resource Review Vol.14. No.2, pp [10] Lemeshko N.A. Water level of the largest lakes. /in Book Water resources of Russia and their use. Ed. by I.A.Shiklomanov. St.Petersburg: State Hydrological Institute pp [11] Lemeshko N.A., Gronskaya T.P. Changes in hydrological regime of reservoirs and largest lakes of Russia: consequences for humans. Human dimension and global environmental changes. IHDP Proceedings. Zvenigorod,2005. pp [12] Gronskaya T. P. Water balance of the largest lakes. /in Book Water resources of Russia and their use. Ed. by I.A.Shiklomanov. St.Petersburg: State Hydrological Institute pp [13] Magnuson, J.J., Webster, K.E., Assel, R.A., Bowser, C.J., Dillin, P.J., Eaton, J.G., Evens, H.E., Fee, E.J., Hall, R.I., Mortsch, L.R., Schindler, D.W. and Quinn, F.H. Potential effects of climate changes on aquatic systems: Laurentian Great Lakes and Precambrian Shield region. J. Hydrol Proc. 11: [14] Vuglinsky V.S., Gronskaya T.P. and Lemeshko N.A. Long-Term Characteristics of Ice Events and Ice Thickness on the Largest Lakes and Reservoirs of Russia. Ice in the Environment: Proceedings of the 16th IAHR International Symposium on Ice Dunedin, New Zealand, 2nd 6th December International Association of Hydraulic Engineering and Research pp [15] Gronskaya, T.P. Ice thickness in relation to climate forcing in Russia. Verh. Internat. Verein.Limnol (5): [16] Vuglinsky V.S., Gronskaya T.P. Changes in Ice Events on rives and on water bodies of Russia and their possible consequences to economy.

7 Present situation in hydrometeorology. Asterion, 2006, , (in Russian). [17] IPCC 2001: Climate The Scientific Basis. -Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 2001, 881 р. [18] Climate Change The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Solomon S. D., Qin M., Manning Z., Chen M., Marquis K. B., Averyt M., Tignor M., and Miller H. L., eds., Cambridge, United Kingdom and New York, NY, USA, Cambridge University Press, p. [19] Lemeshko N.A. Climate change. Scenarios of Global Warming. Regional changes in temperature, precipitation and soil moisture content. Book of Lectures on National School for Young Researchers/Practical Experts on Precession Agriculture. St.-Petersburg pp [20] Lemeshko, N.A. Land hydrological regime with doubling of atmospheric carbon dioxide. Climate changes and their consequences. St.Petersburg. Nauka, p (in Russian) [21] Borzenkova, I.I., Cenozoic climatic change. St.Petersburg, USSR: Gidrometeoizdat, p. [22] Lemeshko, N.A., Borzenkova I.I. Hydrological regime of the largest Russian Freshwater Lakes by 2 C global warming. Proceedings of 9-th International Conference on the Conservation and Management of Lakes November Japan, v.5, pp [23] Lemeshko N. The largest lakes and reservoirs of Russia as a priority water resource for society. Global change research. Abstracts. New Methodologies and Interdisciplinary Approaches in Global Change Research pp