Earth harbours 20,000,000,000,000,000 ants – and they weigh more than wild birds and mammals combined

A study estimate the world’s ants collectively constitute about 12 million tonnes of dry carbon.

Have you ever wondered exactly how many ants live on Earth? Possibly not, but it’s certainly a question we’ve asked ourselves.

Our research published today provides an approximate answer. We conservatively estimate our planet harbours about 20 quadrillion ants. That’s 20 thousand million millions, or in numerical form, 20,000,000,000,000,000 (20 with 15 zeroes).

We further estimate the world’s ants collectively constitute about 12 million tonnes of dry carbon. This exceeds the mass of all the world’s wild birds and wild mammals combined. It’s also equal to about one-fifth of the total weight of humans.

Eminent biologist Edward O Wilson once said insects and other invertebrates are “the little things that run the world” – and he was right. Ants, in particular, are a crucial part of nature. Among other roles, ants aerate the soil, disperse seeds, break down organic material, create habitat for other animals and form an important part of the food chain.

Estimating ant numbers and mass provides an important baseline from which to monitor ant populations amid worrying environmental changes.

There are more than 15,700 named species and subspecies of ants, and many others not yet named by science. Ants’ high degree of social organisation has enabled them to colonise nearly all ecosystems and regions around the globe.

The astounding ubiquity of ants has prompted many naturalists to contemplate their exact number on Earth. But these were basically educated guesses. Systematic, evidence-based estimates have been lacking.