Plants account for about 80 per cent of Earth’s biomass measured as carbon, roughly 450 gigatonnes, while estimates suggest human land use has cut the amount of carbon stored in vegetation to about half its potential level

Of all the carbon locked up in living things, plants hold roughly four-fifths of it. Not mammals, not fish, not the microbes beneath our feet. Trees, grasses, shrubs, and everything green.

That figure comes from a 2018 census of life, and it sits next to a second, more uncomfortable one. The plants standing today hold only about half the carbon they would if humans had never cleared, grazed, or managed the land.

So the planet is overwhelmingly made of plants, and its plant world is running at roughly half of what it could be. Setting those two facts together is where this gets interesting.

We are not ecologists, climate scientists, or carbon-cycle researchers. What follows is our reading of two peer-reviewed studies. Both are estimates that carry real uncertainty, not settled measurement. The figures describe the planet at a global scale and shouldn’t be mistaken for precision down to the last gigatonne.

The census that counted everything

The first number came out of an attempt to weigh all life on Earth at once. Biologist Ron Milo and colleagues at the Weizmann Institute published a census in 2018, and their tally found that plants make up about 80 percent of the roughly 550 gigatonnes of carbon held in all living things. That’s around 450 gigatonnes in plants alone, overwhelmingly land plants and trees.

One choice in how they counted matters more than it sounds. They measured everything in carbon rather than raw weight. Carbon is the shared currency of living tissue. Counting it lets you line up a bacterium against a redwood and ask which holds more of the stuff life is actually built from.

Measured that way, the ranking is lopsided. All animals combined come to about 2 gigatonnes of carbon, a rounding error against the plant total. Bacteria alone hold something like 70. And humans? About 0.01 percent of the whole. Milo found the result striking. “It is definitely striking,” he told The Guardian, “our disproportionate place on Earth.”

It helps to picture what that plant carbon really consists of, because “plants” can conjure a field of wildflowers when the truth is closer to a forest of trunks. The 450 gigatonnes is mostly wood. The carbon banked in stems, roots, and standing timber dwarfs the leafy, green part we tend to imagine.

The other number: what’s missing

So plants dominate. That’s the first view, and it’s genuine. The second starts from a different question: not how much carbon vegetation holds now, but how much it would hold if we’d left it alone.

A separate 2018 study, led by Karl-Heinz Erb, tried to answer that. The team compared the vegetation standing today against a modeled version of the planet with no human land use, given today’s climate. Erb and colleagues put current stocks at around 450 petagrams of carbon and the undisturbed potential at around 916. Roughly half the carbon that could be standing in the world’s vegetation isn’t there.

The reasons split into two rough halves. Clearing land for fields and cities accounts for something like 53 to 58 percent of the shortfall. The rest, 42 to 47 percent, comes from how we manage land we haven’t cleared at all: logging that keeps forests younger and lighter than they’d naturally grow, and grazing that holds grasslands below their potential.

Reconciling a planet that is both

The two numbers don’t contradict each other, though at first they feel like they might.

One says plants overwhelmingly rule the living world. The other says that plant world is a shrunken version of itself.

Both are estimates, and worth reading as ranges rather than fixed points. The “potential vegetation” idea is a model of a world that doesn’t exist, and later researchers have refined it. A 2025 analysis in One Earth that looked at vegetation and soils together put the total loss of land carbon at about 24 percent, a smaller figure that counts different things and defines the starting point differently. The exact fraction shifts depending on what you measure and how you imagine the undisturbed world. The direction doesn’t.

What we take from setting the two figures together is less a tidy lesson than a corrected picture. The instinct to put ourselves, and animals, at the center of life on Earth is exactly the instinct the census undoes. Milo said as much about what he hoped the work would do. “I would hope this gives people a perspective on the very dominant role that humanity now plays on Earth,” he said. We are a vanishingly small share of the carbon in living things, and we have still managed to cut the largest share of all, the plants, to roughly half of what it might be.