The total mass of life on Earth may be one-third less than thought, altering how active we think life on our planet is, researchers say. Past estimates of how much life there is on Earth suggested living organisms store about 1 trillion tons of carbon, of which about 30% dwells in single-celled microbes in the ocean floor, and about 55% rests in land plants.

However, it turns out previous estimates of the amount of life in the ocean floor were based on samples taken in very nutrient-rich areas, such as close to shore. About half the world’s ocean is extremely nutrient-poor, meaning that comparably little in the way of life should be found there. Writing in the journal Proceedings of the National Academy of Sciences, the researchers estimate about 4 billion tons of carbon are stored in microbes in the ocean floor instead of 300 billion tons. This reduces the estimated amount of the world’s biomass drastically by about a third.