Over 90% of the world's biomass is in—

Global biomass distribution is heavily skewed toward terrestrial environments, which account for approximately 86% to over 90% of the total living biomass on Earth. Plants are the dominant kingdom, comprising roughly 450 gigatons of carbon (Gt C) out of a total 550 Gt C, and they are primarily located on land [2]. Within terrestrial ecosystems, forests—particularly tropical rain forests—hold the vast majority of this biomass due to their high net primary productivity and the accumulation of carbon in wood and soil over decades [1]. In contrast, despite covering over 70% of the Earth's surface, oceans contain only about 1% of the total global biomass. While some older sources suggested marine biomass was higher, modern censuses confirm that terrestrial plants, especially those in tropical regions, represent the overwhelming majority of the world's standing crop [2].

Sources

1. [2] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 21: Mitigation Strategies > 2r.2.1. Green Carbon > p. 282
2. [1] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > biomass Pyramid > p. 24