Figure 6.

Globally predicted optimal rates of $V_{\mathrm{cmax}}^{\prime }$. Global ‘present‐day’ optimal rates of maximum Rubisco carboxylation ($V_{\mathrm{cmax}}^{\prime }$) computed using mean growing season irradiance, air temperature, vapour pressure deficit and elevation. Values were calculated at 0.5° resolution using effective growing season mean temperature (T _g; °C), atmospheric vapour pressure deficit (D _g; Pa) and incoming photosynthetically active radiation (I _g; μmol m⁻² s⁻¹) for each location from monthly data provided by the Climatic Research Unit (CRU TS3.24.01) (Harris et al. 2014). Growing season was defined as months having temperatures greater than 0 °C. Elevation (z; m) at each location was obtained from the WFDEI meteorological forcing dataset (Weedon et al. 2014). Atmospheric CO ₂ was assumed to be 400 μmol mol⁻¹ at z = 0 m and converted to Pa for each location based on z.