Fig. 2. Regionalized observed (1950–2000 AD) and simulated (2000–2050 AD) annual temperatures (thin solid lines) and vegetation growing season temperatures (thick solid lines) for two scenarios from the Intergovernmental Panel on Climate Change Special Report Emissions Scenarios (IPCC-SRES 2000): B2 (dark grey) and A1FI (light grey). The average temperature of the vegetation periods from 1961 to 2010 is presented as a reference threshold (thick dashed black line). The difference between simulated yearly temperatures of vegetation periods and this reference threshold is implemented as a parameter ∆T driving drought stress in simulations. The average temperature of the last 50 years (thin dashed line) is used to simulate the increase in productivity due to the prolongation of the vegetation period.