Optimum climate of the Kazantsev interglacial period is studied (130.000-121.000 years ago). The history of vegetation is restored and distribution of vegetation zone within the interglacial optimum is shown according to the palynological data of 22 open cuts situated in different modern landscape zones. It is concluded that the modern border of the forest zone at the period of the Kazantsev optimum coincides with the southern line of the bank of the Kazantsev sea. Displacement of the northern border is up to 500-600 km. Forest-tundra and tundra zones did not exist and northern border of the forest-steppe zone migrated to the north for 200-300 km. By means of climatograms quantitative assessments of temperatures of January and July, average annual temperature were obtained for the first time for optimum climate of the Kazantsev interglacial period. The presented maps were designed in isotherms, and deviations of paleotemperatures from modern values are shown. To the north from 65 N average annual temperatures were higher than modern ones. Deviations of the average annual temperatures from modern values increase up to +6 - +7 degrees-C in the Artic zone. Regions with risky exploitation of nature are marked. Temperature data can be used to forecast the climate at the middle of the 21th century.
