Extended Data Fig. 5: Changes in regional climate, satellite greenness and plant carbon fluxes from observation-constrained and modelling approaches for warm- and cold-spring years.
From: Widespread seasonal compensation effects of spring warming on northern plant productivity
a–f, Monthly anomalies in regionally averaged maximum composited climate (a, d), NDVI (b, e) and GPP (c, f) for warm- and cold-spring years, for the focus regions (a–c, western USA; d–f, Siberia). The anomalies are relative to the mean of the study period (1982–2011) and are based on maximum composites of monthly means of the seven warmest- and coldest-spring years within the study period. The observation-constrained GPP anomalies (c, f) stem from FluxNetG, which combined GPP estimates from flux towers with climate and satellite greenness in a machine-learning framework (see Methods). The boundaries between the climatological seasons are indicated by vertical grey dashed lines. Uncertainty bounds (shaded areas) reflect the spread in the respective monthly anomalies within the compositing period (±1 s.d., n = 7). On the basis of these anomalies, we estimate, for a warm-spring year (relative to mean conditions) in Siberia (area, 2.5 × 106 km2), annual GPP increases of 0.4 Pg C and 1.7 Pg C for FluxNetG and the TRENDYv6 ensemble, respectively, which corresponds to higher plant carbon uptake in the TRENDYv6 ensemble by a factor of roughly four (f). This is, to a large extent (about 64%), because of the overestimation of positive lagged effects in the TRENDYv6 models, but another important factor (36%) is the higher sensitivity of concurrent carbon uptake to spring warming in the TRENDYv6 models (compared to FluxNetG).
