2. Detecting Arctic Change Using the Koppen Climate Classification Muyin Wang 1 James E. Overland 2 1 JISAO/UW, 2 PMEL/NOAA, Seattle, WA Photos from the Ayiyak River (Alaska) show an increase in shrubs. Sturm et al., 2001, Nature & Satellite NDVI

3. The Koppen Classification TemperateDT>= 10 o C for 4 or more months BorealET>= 10 o C for 1-3 months Polar TundraFt0 o C <= T <10 o C in summer Perpetual FrostFiT < 0 o C in summer Data NCEP/NCAR reanalysis 2.5x2.5 1948-2002 CRU/UA TS2.0 0.5x0.5 1901-2000 Mitchell, et al, 2003 Kalnay, et al, 1996

4. Tundra Frost Boreal Temperate Vegetation Distribution based on Koppen Classification NCEP CRU 1978 1950 1998

5. Calculated Vegetation Distribution Based on CRU/ Tundra Boreal Temperate NCEP 10 6 km 2

6. Satellite Normalized Differences Vegetation Index (NDVI) is calculated from the visible (VIS) and near- infrared (NIR) light reflected by vegetation in the AVHRR channels. NIR – VIS NIR + VIS NDVI = Global monthly NDVI data set is provided by NASA on 1x1 o resolution from July 1981 to September 2001. The value increases from 0.1 to 0.9 for progressively increasing amounts of green vegetation.

7. 1.0 0.8 0.6 0.4 0.2 0.0 Distribution of vegetation type based on Koppen classification The lost tundra areas The summer NDVI climatology The change in NDVI from 1980s to 90s

8. CONCLUSIONS  The potential impact of vegetation changes to feedbacks on the climate system is enormous because of their large land area and multiyear memory of the vegetation cover in the Arctic region. The Koppen classification based on SAT agrees well with satellite NDVI. Both indicate a significant decrease in the tundra area in the past 20 years – about 1 million km 2 lost. A similar decreasing trend was seen in the early 1900s, but with smooth slope.

9. The Area of Tundra Group Based on CRU SAT And the Averaged NASA NDVI for 50-90 o N Correlation = -0.70

10. Scandinavia Siberia N.W. America N.E. America Tundra Boreal + Temperate Anomalies of Vegetation Group for Sub-regions

11. THE LOST TUNDRA AREA: Max - Min CRU: 1950 – 1998NCEP: 1978 -1998

13. Anomalies of Tundra & Boreal for sub-regions in Arctic Scandinavia Siberia N.W. America N.E. America Tundra Boreal 10 6 km 2 10 o W ~120 o E 120 o E ~170 o W 170 o W ~80 o W 80 o W ~40 o W