Phenology metrics were inter-compared for 10 PFT algorithms and 7 CMIP5 models. The Discrete Fourier Transform was used to quantify phenological metrics. Global scale metrics are similar among algorithms, but differences exist. Cleanest microplankton seasonality is found in zonal bands about 30–40°N/S. CMIP5 models fail to reproduce secondary blooms in zonal bands at mid-latitudes.