Marine Forests in a Changing Climate: Projecting Global Trends in Extent and Biomass DistributionScience to Policy

Lauren Vapillon¹, Sofie Vranken¹, Olivier De Clerck¹, Jorge Assis²

¹Ghent University, Belgium - ²Universidade do Algarve, Portugal

Over the past 50 years, the combined effects of climate change and anthropogenic disturbances have driven significant changes in marine forests worldwide, with foundational species exhibiting notable shifts in distribution and abundance, and trends of decline. With rising demand for seaweeds in various industrial applications and uncertain compliance with climate change mitigation, it is crucial to understand marine forest trajectories as these have remained poorly evaluated for decades.

Here, we provide an assessment of the global extent of marine forests’ standing biomass for present-day and various Shared Socioeconomic Pathways (SSPs) scenarios. Using in situ measurements from over 500 sites and 150 taxa compiled from the past 30 years of literature, we generate maps of biomass distribution, identifying areas of gain and loss, and decipher global trends by the end of the century. Our study reveals significant climatic drivers governing the dynamics of marine forests through space and time, and corroborates previous research highlighting local stressors as primary factors of forest change. The projections made will serve as new baselines to further evaluate the resilience of marine forest habitats and their derived ecosystem services, supporting management directives and guiding conservation actions while considering future changes in niche availability.