The first world map of the laminarian kelp biome has been published (Jayathilake and Costello (2020). It estimates the kelp biome to occupy 1,469,900 km2 and be present on 22 % of the world’s coastline. It is thus the second most widely distributed marine biome, following seagrass with 1,646,788 km2 (Jayathilake and Costello 2018).
The map was modelled based on the over 44,000 field observations in the map below.
The map has contributed to a world map of marine biodiversity that included species richness, endemicity, ecosystems and biomes (Zhao et al. 2020), that has won an award for its potential contribution to the UN Sustainable Development Goals.
The map is included in the WCMC UNEP Ocean Data Viewer platform. The short link for the data pack download is here.
The map has been updated with new data from the Arctic. The kelp biome is now 2 million km2 and the largest marine biome. It was profiled in Science: 
References
Jayathilake D.R.M., Costello MJ. 2018. A modelled global distribution of the seagrass biome. Biological Conservation 226, 120-126. https://doi.org/10.1016/j.biocon.2018.07.009
Jayathilake D.R.M., Costello MJ. 2020. A modelled global distribution of the kelp biome. Biological Conservation 252, 108815. https://doi.org/10.1016/j.biocon.2020.108815
Jayathilake D.R.M., Costello M.J. 2021. Version 2 of the world map of laminarian kelp benefits from more Arctic data and makes it the largest marine biome. Biological Conservation online. https://doi.org/10.1016/j.biocon.2021.109099
Zhao Q, Stephenson F, Lundquist C, Kaschner K, Jayathilake DRM, Costello MJ. 2020. Where Marine Protected Areas would best represent 30% of ocean biodiversity. Biological Conservation 244, 108536. https://doi.org/10.1016/j.biocon.2020.108536
