Is Central Asia really exsiccated? Vladimir and Elena Aizen, Arzhan Surazakov University of Idaho

1. Is Central Asia really exsiccated? Vladimir and Elena Aizen, ArzhanSurazakov University of Idaho People of central Asia totally depend on seasonal snow and glacier melt water. Without snow and glaciers, central Asia will dry out.

2. From ancient to modern irrigation systems • Agricultural and industrial expansion • Population grows

3. Objective: What is the past century climate and water resources changes in • central Asia? • Data: Long-term observational data and assimilated remote sensing information. Aerial (1943), remote sensing data (Corona, Hexagon KH-9, Landsat, Aster, SRTM and MODIS – collection 4-5) • Methods: • Thiessen’s spatial averaging/polygon method to interpolate gaps in meteorological data. • - differences in averages for two thirty-year periods 1972-2002 &1942-1972 • T-test at 20% for precipitation and 10 % for air temperature level • - linear trends for the same periods. Coefficients of determination, F tests at 80% for • precipitation and 90% for air temperature level of significant • - acceleration in changes for the last thirty years is difference in trends • - differences in standard deviations and coefficient variations two thirty-year • periods. • Geographically weighted regression (GWR) method for spatial interpolation of precipitation (P) and temperature (T) data. The optimal size of the kernel is 30 neighbors • Imagery processing

4. Recent research on climate changes over the Central Asia

5. 264 Central Asian hydro-meteorological stations used for analysis Central Asia by climatic zones Number of stations by elevations Main periods of observations 1942-1972 and 1973-2003

6. Differences in 30-year averages of annual (A) and summer (B) air temperature (Δ = AVE1973-2003 – AVE1942-1972) A B Average weighted differences between annual, annual-maximum & summer means temperatures (1973-2003 and 1942-1972) for climatic regions Average weighted differences annual, annual-maximum and summer means of air temperatures (1973-2003 and 1942-1972) for altitudinal belts

7. Acceleration in changes of annual (A) and summer (B) air temperature for the last 30 years (Δ = SLOPE1973-2003 – SLOPE1942-1972) A B

8. Differences in 30-year averages of annual precipitation (Δ = AVE1973-2003 – AVE1942-1972) (A) altitudinal distribution of central Asia areas (S, km2), (B) average weighted differences in annual precipitation for the periods from 1973- 2003 and 1942-72 (Δ, km3 )

9. Altitudinal distribution of average weighted differences of annual precipitation for the periods from 1973- 2003 and 1942-72(b) (Δ, km3) by climatic regions

10. Differences in 30-year averages of winter (A) and summer (B) precipitation (Δ = AVE1972-2002 – AVE1942-1972) A B

11. Acceleration in changes of annual precipitation Δ = SLOPE1972-2002 – SLOPE1942-1972) Accelerating altitudinal changes of precipitation for the last 30 years compared to the previous 30 years , Acc = Sl1972-2005 - Sl1942-1972, mm Accelerating changes by region of precipitation for the last 30 years compared to the previous 30 years , Acc = Sl1972-2005 - Sl1942-1972, mm

12. Overall decadal trends show the high dust loading for the 1960’s and 70’s, with maximum dust loading apparent for the 30’s and that is in accordance with results from 154 Chinese stations on maximum frequency of dust weather for the mid-1960’s (Qian et al;Sun et al., 2002) and the lowest in the 90’s to be one-fifth that of the 60’s.

13. Tien Shan, number of days with snow 2000-2001 The seasonal snow covered area in Tien Shan decreased by 15% approximately 120 000 km2 Tien Shan, number of days with snow 2006-2007

14. Snow covered areas by 1,000m isohyps over the Tien Shan for the last twenty years reconstructed by surface observational, AVHRR and MODIS data Duration of snow melt from the date of maximum snow cover to date of it’s disappearance reduced on 30 days during the last twenty years, equal 138 days in 2007. Snow melt 30 days faster then 20 years ago. The decrease of snow cover is not linear process. ten days AVHRR data calibrated with surface observational data eight days MODIS data

15. 1,617 km2 (-10.1%) glacier area reduction during the last thirty years in Tien Shan K A Z A K H S T A N C H I N A 0 50 150 km

16. Inner Tien Shan area Aksiirak glacierized massif 182 glaciers; 427 km2 glacierized area (aerial photogrammetry 1943) 1943 1977 2003 182 glaciers; 406.8 km2 glacierized area; 4.2% area reduction (aerial photogrammetry 1943/1977) 178 glaciers; 371.6 km2 glacierized area; 8.7% area reduction (aerial photogrammetry 1977/ASTER 2003) Petrov Glacier 2003 2002 1995 1977 1956 1943 1869 1800

17. Conclusion • Statistically significant difference in means of annual and seasonal precipitation and air • temperature for two 30-year periods was observed at more than 73 (precipitation) and /93% • (air temperature) of 264 stations • The last 30-years average precipitation has decreased on 0.1% of average compared with • previous 30-years • The last thirty year deficit of precipitation income was -62 km3 that is about 6 % from total • 1,048 km3 volume Tien Shan glaciers • The most significant deficit in precipitation income observed at the alpine regions and • Kazakhstan steppes during summer season • Acceleration in decrease of precipitation for the last 30 years for all central Asia • Increased precipitation in winter at low altitudes, at Aral-Caspian and Tarim basin deserts, • western and even Eastern Pamir • Increased annual air temperatures for the last 30 years on 0.68°C by increased summer air • temperatures • Total central river runoff have decreased on 4% in all central Asia • Snow covered areas shrunk by 15% and glacier covered area by 10% over the last 30 years