STUDY OF ENVIRONMENTAL IMPACTS OF CLIMATE CHANGE OF ARAL SEA BASIN

Abstract

Observed climate change (global warming) is directly related to greenhouse gas (GHG) concentration increase in atmosphere. Global warming rates, scales as well as its effect in some regions depend on global GHG emissions volume in atmosphere of the Earth in future. In 1992 Intergovernmental Plane on Climate Change (IPCC) proposed 6 GHG emissions scenarios (IS92a, IS92b, IS92c, IS92d, IS92e, and IS92f). Scenario IS92a assumes that global population would increase up to 11.3 billion by 2100, economical growth would be 2.3-2.9% annually, and. besides no attempts' of restricting GHG emissions in atmosphere would be made. This is so called "business as usual" scenario. Scenarios IS92c K IS92d assume less quantity of emissions against scenarios IS92a K IS92b, and scenarios IS92e H IS92f — greater quantity due to difference in assessments of population increment, economical growth, use of various types of fuel and power sources. According to above mentioned scenarios there are the same number of global air temperature increase alternatives, moreover each variant has own uncertainty limits. The most reliable tool for modeling physical processes, which define climatic changes, are three-dimensional numerical models of general circulation (GCM). Its advantage is that basing on conservation laws models, as much as possible, account physics of processes, which allow simulation and prediction of climate. However GCM has some constraints including horizontal resolution of models, which does not provide adequate regional climate simulation. Great averaging on area, typical for global models, reduces amplitude of fluctuations of regional climatic characteristics. Quality of air temperature changes simulation by climatic models in scale of hemispheres and continents is higher than for specific regions. Moreover, quality of regional climate change assessment depends on region location, its physical-geographical conditions, and used models. While developing climate change scenarios on GCM basis it is necessary to take into account its different sensitivity. Regarding this climate sensitivity parameter is widely used, which is defined as global average air temperature variation by the surface iii in state of balance, which occurs in response for CO2 concentration doubling in atmosphere. This parameter values are in range 1.5-4.5°C. In spite of significant uncertainties, GCM is successfully applied for global climate description in general and specific regions climate description as well. Results obtained on global models of general circulation of atmosphere and oceans are the most favorable basis for formation of climate change scenarios and regional vulnerability assessments. When using global models results to assess regional climatic changes, it is necessary to take into account geographical features of certain regions, which are related to location relief, water objects, character of underlying surface etc. For this purpose «downscaling» methodic are used, by means of which climatic characteristics, given by models, are transformed to required for further use meteorological parameters with proper spatial and temporal resolution. In given work regional climatic scenarios are built by method of statistical interpretation based on concept of "ideal forecast" described in (Spektorman, 2002) using gradual linear regression. On the basis of analysis conducted for assessment of future changes of average climatic characteristics values of Uzbekistan and adjacent mountainous area following methodic is used: - determination of statistical dependencies between climatic characteristics in local and global scales - use of model global temperature assessments as future global' climate forecasts for different IPCC emission scenarios. - use of existing in series climatic characteristics of Uzbekistan quasi-cyclicities and tendencies to reduce uncertainty, correct scenarios and assessment of possible course of researched values. Assessment of climatic conditions changes over Central Asia territory with account for available model assessments, regional analogous scenario and empirical-statistical approach show that we should expect some increase (from 0 to 20%) of total precipitation sums and temperature increase in all seasons of the year over Central. Asia area, including flow formation zone, under realizing different GI-TG emission scenarios by 2030.