COMP ARA TIVE DROUGHT STRATEGIES THE SOVIET UNION

Background. It cannot be emphasized enough that the Soviet Union is a highlatitude country. Odessa on the Black Sea coast, one of Russia\u27s southern cities, lies at a latitude of 46°N, comparable to that of Billings, Montana, and in fact is cooler in summer than Billings (Lydolph 1977b). Krasnodar in the Kuban District of the North Caucasus, probably the most productive region in the Soviet Union, compares latitudinally and climatically to St. Paul, Minnesota. Kharkov, in the northeastern Ukraine, compares to Winnipeg, Canada; in fact, Winnipeg experiences higher maximum temperatures in summer than Kharkov does. The central black earth region of the Russian Republic lies even farther north. Thus, most of the farmland of the Soviet Union is more comparable latitudinally and climatically to parts of Canada than to the United States. In the wheat lands of southwestern Siberia, Omsk, at a latitude of 55°, lies farther north than any agricultural settlement in Canada, except perhaps the Peace River Valley, which, of course, is only a restricted area. In these northern regions, the Soviets must consider not only moisture supply but always heat supply as well (Lydolph 1963)

Holocene oxygen isotope record of diatoms from Lake Kotokel (southern Siberia, Russia) and its palaeoclimatic implications

The oxygen isotope composition of diatom silica (d18Odiatom) from marine and lake sediments is helpful for the interpretation of the past climate and environments, especially when complemented by other proxy records. This paper presents a Holocene oxygen isotope record of diatoms from Lake Kotokel, located 2 km east of Lake Baikal in southern Siberia, Russia. The isotope record displays variations in d18Odiatom from +23.7 to +30.3‰ from about 11.5 ka BP until today. Comparing the isotope composition of recent Lake Kotokel water (mean d18O = -12‰) to that of the most recent diatom sample (d18O = +27.5‰), an isotope fractionation in the right order of magnitude was calculated. The Kotokel d18O diatom record is rather controlled by changes in the isotopic composition of the lake water rather than by lake temperature. Lake Kotokel is a dynamic system triggered by differential environmental changes closely linked with various lake-internal hydrological factors. A continuous depletion in d18O of 6.6‰ is observed from Early to Late Holocene, which is in line with other hemispheric environmental changes (i.e. a Mid- to Late Holocene cooling). Enhanced evaporation effects and higher relative supply from a southerly moisture source explain the relatively heavy isotopic composition in a rather cold Early Holocene. In summary, changes in the Holocene d18O diatom record of Lake Kotokel reflect variations in d18O of precipitation linked with both Tair as well as evaporation effects and, to a lesser degree, meltwater pulses from the mountainous hinterland and changing atmospheric moisture sources

Interactions between mass balance, atmospheric circulation, and recent climate change on the Djankuat Glacier, Caucasus Mountains, Russia

This paper reports recent changes in the mass balance record from the Djankuat Glacier, central greater Caucasus, Russia, and investigates possible relationships between the components of mass balance, local climate, and distant atmospheric forcing. The results clearly show that a strong warming signal has emerged in the central greater Caucasus, particularly since the 1993/1994 mass balance year, and this has led to a significant increase in the summer ablation of Djankuat. At the same time, there has been no compensating consistent increase in winter precipitation and accumulation leading to the strong net loss of mass and increase in glacier runoff. Interannual variability in ablation and accumulation is partly associated with certain major patterns of Northern Hemisphere climatic variability. The positive phase of the North Pacific (NP) teleconnection pattern forces negative geopotential height and temperature anomalies over the Caucasus in summer and results in reduced summer melt, such as in the early 1990s, when positive NP extremes resulted in a temporary decline in ablation rates. The positive phase of the NP is related to El Nino-Southern Oscillation, and it is possible that a teleconnection between the tropical Pacific sea surface temperatures and summer air temperatures in the Caucasus is bridged through the NP pattern. More recently, the NP pattern was predominantly negative, and this distant moderating forcing on summer ablation in the Caucasus was absent. Statistically significant correlations are observed between accumulation and the Scandinavian (SCA) teleconnection pattern. The frequent occurrence of the positive SCA phase at the beginning of accumulation season results in lower than average snowfall and reduced accumulation. The relationship between the North Atlantic Oscillation (NAO), Arctic Oscillation, and accumulation is weak, although positive precipitation anomalies in the winter months are associated with the negative phase of the NAO. A stronger positive correlation is observed between accumulation on Djankuat and geopotential height over the Bay of Biscay unrelated to the established modes of the Northern Hemisphere climatic variability. These results imply that the mass balance of Djankuat is sensitive to the natural variability in the climate system. Distant forcing, however, explains only 16% of the variance in the ablation record and cannot fully explain the recent increase in ablation and negative mass balance