Temperature influences the metabolic rates and geographic ranges of phytoplankton, with implications for global primary production and biogeochemical cycling. Variation in the physiological effects of temperature across species and phytoplankton functional types (PFTs) can lead to altered marine phytoplankton biogeography and community structure. We assessed phytoplankton thermal trait variability in order to a) better understand how thermal trait variability could explain phytoplankton community dynamics and b) assess the relative capacity of phytoplankton to cope with thermal change.