Table 1. Linear trends (with r and P values in parentheses) in the extratropical spring (MAM) and growing-season (MAMJJA) temperatures, and in net spring and growing-season CO2 uptake for the two time periods studied
Time period Spring air temperature, °C/yr Net spring CO2 uptake, ppm/yr Growing-season temperature, °C/yr Net growing-season CO2 uptake, ppm/yr
1985-1991 0.087 (0.73, 0.06) 0.10 (0.61, 0.15) 0.081 (0.88, 0.009) 0.14 (0.75, 0.05)
1994-2002 0.062 (0.64, 0.06) 0.09 (0.67, 0.05) 0.044 (0.66, 0.05) 0.004 (0.04, 0.91)
  • The year 1985 is when the number of operating CO2 stations was sufficient to allow robust study of interannual variations. Positive temperature trends are evident in both time periods and evident for both spring and the entire growing season. Net growing-season CO2 uptake goes from a positive trend in the early period to a stalling in the late period, whereas net spring uptake increased in both periods.