## 3 Results and Discussion  
### Observed Climate and NDVI Trend for 1982-2011  
For the 1982-2011 period, the temperature increased over most regions; precipitation had a geographically variable pattern in the sign of the trends (Figure 2). Distinct increases in temperature were distributed over eastern Siberia (60\({}^{\circ}\)N-75\({}^{\circ}\)N, 110\({}^{\circ}\)E-180\({}^{\circ}\)E) and semiarid regions around inner-Mongolia (45\({}^{\circ}\)N-50\({}^{\circ}\)N, 100\({}^{\circ}\)E-130\({}^{\circ}\)E). Precipitation had distinct increases in eastern Siberia (60\({}^{\circ}\)N-75\({}^{\circ}\)N, 110\({}^{\circ}\)E-180\({}^{\circ}\)E) and part of India (10\({}^{\circ}\)N-25\({}^{\circ}\)N, 70\({}^{\circ}\)E-80\({}^{\circ}\)E), with distinct decreases in semiarid regions around inner-Mongolia (45\({}^{\circ}\)N-50\({}^{\circ}\)N, 100\({}^{\circ}\)E-130\({}^{\circ}\)E). Increasing trends in the NDVI were dominant in Asia for the 1982-2011 period (Figure 3). Moreover, 41.8% of the vegetated regions had increased NDVI values, with distinct increases in eastern Siberia (50\({}^{\circ}\)N-80\({}^{\circ}\)N, 100\({}^{\circ}\)E-180\({}^{\circ}\)E), boreal Eurasia (45\({}^{\circ}\)N-60\({}^{\circ}\)N zones), parts of China and India, and some scattered regions in tropical Asia. However, the regions with significant NDVI  
Figure 2: Trend in (**a**) growing season average temperature (\({}^{\circ}\)C\(\cdot\)30 y\({}^{-1}\)) and (**b**) annual total precipitation (%\(\cdot\)30 y\({}^{-1}\)) from 1982 to 2011. The trend slope was estimated using the Kendall robust line-fit method. Solid black lines in the map show the sub-continental division (only for the Eurasian continent) defined in Figure 1b. decreases were distributed among small regions (2.9% of the vegetated regions); for example, parts of western Arctic Siberia (60\({}^{\circ}\)N-80\({}^{\circ}\)N, 80\({}^{\circ}\)E-100\({}^{\circ}\)E) and semiarid regions around inner-Mongolia (45\({}^{\circ}\)N-50\({}^{\circ}\)N, 100\({}^{\circ}\)E-120\({}^{\circ}\)E). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Region** & **NDVI** & **BEAMS** & **Biome-BGC** & **LPJ** & **TRIFFID** \\ \hline Boreal Eurasia North West & 0.015 & 0.5 (2.5) & 2.4 (9.2)\({}^{**}\) & 3.2 (11.8)\({}^{**}\) & 3.8\({}^{**}\) (14.6) \\ Boreal Eurasia North East & 0.068\({}^{**}\) & 1.3 (5.3)\({}^{**}\) & 3.6 (14.7)\({}^{**}\) & 5.0 (19.6)\({}^{**}\) & 5.7\({}^{**}\) (21.1) \\ Boreal Eurasia South West & 0.041\({}^{**}\) & 1.9 (5.5)\({}^{**}\) & 5.9 (16.5)\({}^{**}\) & 5.5 (15.3)\({}^{**}\) & 3.5\({}^{**}\) (9.2) \\ Boreal Eurasia South East & 0.034\({}^{**}\) & 1.8 (6.2)\({}^{**}\) & 1.9 (6.1)\({}^{**}\) & 3.4 (11.4)\({}^{**}\) & 0.8 (2.5) \\ Temperate Asia North West & 0.024\({}^{**}\) & 1.4 (4.6)\({}^{**}\) & 0.6 (2.3)\({}^{*}\) & 2.9 (9.3)\({}^{*}\) & 0.9\({}^{**}\) (3.0) \\ Temperate Asia North East & 0.020\({}^{**}\) & 1.7 (11.8)\({}^{**}\) & 2.5 (17.8)\({}^{**}\) & 1.3 (9.9)\({}^{*}\) & 1.4\({}^{*}\) (11.2) \\ Temperate Asia South East & 0.032\({}^{**}\) & 3.7 (15.5)\({}^{**}\) & 0.9 (4.1)\({}^{**}\) & 4.2 (17.4)\({}^{**}\) & 2.7\({}^{**}\) (11.6) \\ Tropical Asia North & 0.023\({}^{*}\) & 5.1 (21.2)\({}^{**}\) & 6.6 (27.2)\({}^{**}\) & 7.1 (29.9)\({}^{**}\) & 4.5\({}^{**}\) (18.9) \\ Tropical Asia South & 0.013 & 3.0 (11.9)\({}^{**}\) & 11.8 (46.0)\({}^{**}\) & 7.9 (30.8)\({}^{**}\) & 7.9\({}^{**}\) (30.9) \\ \hline \hline \end{tabular}  
Statistically significant trends are marked as **(\(p<0.05\))** and * (\(p<0.1\)).  
\end{table} 
Table 1: Temporal trends in the NDVI (NDVI 30 y\({}^{-1}\)) and model-based gross primary productivity (GPP) (gC\(\cdot\)m\({}^{-2}\cdot\)y\({}^{-2}\)) from 1982 to 2011. Values in parentheses are model-based GPP trends (TgC\(\cdot\)y\({}^{-1}\)). Figure 3: Trend in growing season average Normalized Difference Vegetation Index (NDVI) from 1982 to 2011. Only grids with statistically significant trends (\(p<0.05\)) are colored. The Mann-Kendall trend test was applied for the significance test; the slope was estimated using the Kendall robust line-fit method.