Photo by Léonard Cotte on Unsplash

Most people walk past earthworms without a second glance. They're not flashy. They don't roar or soar or hunt in packs. But if you removed every earthworm from the planet tomorrow, the consequences would be catastrophic in ways that would ripple through human civilization within months.

I learned this the hard way while interviewing soil scientists at UC Davis, getting my boots muddy in fields where researchers were literally counting worm burrows. "People think soil is just dirt," Dr. Sarah Chen told me, wiping her hands on her jeans. "But it's a living city. And earthworms are the urban planners."

The Engineering Marvel Happening Underground

An average earthworm doesn't look like much—just a segmented tube with no eyes or ears, maybe three inches long. But here's what's staggering: a single earthworm can move through soil and create tunnels that improve water infiltration by up to 10,000 times. That's not hyperbole. That's measured science.

When it rains, water doesn't just sit on compacted soil. Instead, it follows these tunnel networks down into the earth, where it can be stored and accessed by plant roots. Without this infrastructure, topsoil becomes waterlogged and erodes away. With it, soil becomes this incredibly efficient system for holding water during droughts and preventing flooding during storms.

One hectare of land—about 2.5 acres—can contain up to 1.3 million earthworms. That's 1.3 million individual architects, all working simultaneously to restructure the soil's physical properties. Their burrows also create spaces where air can penetrate, which is essential for the bacteria and fungi that actually make nutrients available to plants.

Carbon Storage and the Climate Crisis

Here's where earthworms become genuinely relevant to everyone, regardless of whether you've ever thought about soil before. Healthy soil is one of Earth's most underrated carbon sinks. When soil organic matter breaks down—a process heavily mediated by earthworms and the microorganisms they interact with—carbon either gets locked away in stable forms or released back into the atmosphere as carbon dioxide.

Research from the University of Vermont found that earthworm activity can increase carbon storage in soil by up to 40% compared to worm-free soil. That might sound like a modest number until you realize we're talking about billions of tons of carbon dioxide that could either be sequestered underground or floating in our atmosphere contributing to climate change.

The mechanism is elegant. Earthworms consume dead organic matter—leaf litter, plant roots, decomposing organisms—and their digestive processes transform it into stable soil compounds called humic substances. These compounds resist further decomposition, essentially locking carbon in place for decades or even centuries.

The Silent Decline We're Not Talking About

Despite their obvious importance, earthworm populations are declining in many regions. Agricultural practices are largely to blame. Intensive tillage—the constant plowing and churning of soil—destroys the burrow systems that earthworms create and expose them to predators. Pesticides and fungicides, particularly neonicotinoids, are toxic to worms at concentrations much lower than those used on farms.

A 2019 study from Germany reported that insect biomass has declined by 75% in recent decades. Earthworms aren't insects, but they're subject to many of the same pressures and pesticide exposures. Some regions report earthworm populations down by 80% compared to historical baselines.

The irony is brutal: farmers unknowingly destroy the very organisms that would make their soil more productive and resilient. A farm with healthy earthworm populations needs less water, holds more nutrients, and recovers better from droughts. It's essentially a natural irrigation and fertilization system that's free once it's established.

What Healthy Soil Actually Looks Like

I visited a regenerative farm in California where the farmer, Marcus, hadn't tilled his soil in six years. When he showed me a soil pit—literally a hole dug down about two feet—the difference was striking. In the regenerative section, the soil was dark, crumbly, and literally teeming with earthworms. I counted 47 in a single shovel full. In a neighboring conventionally managed field? Three worms in the same volume of soil.

"The difference in yield seems small," Marcus said, "but over time, in dry years especially, we see it. Our crops just perform better. The soil holds water. It's got structure." His regenerative fields produced comparable yields to conventional ones during normal years but significantly outperformed them during the 2020-2022 drought.

This isn't just anecdotal. Studies across multiple crops and regions show that soil with healthy earthworm populations demonstrates greater resilience to both drought and flooding, reduced erosion, and improved nutrient cycling. It takes time to rebuild these populations—usually 3-5 years—but the payoff is substantial.

The Path Forward

The good news is that earthworm populations can recover relatively quickly if given the chance. Reducing tillage, minimizing pesticide use, and maintaining plant cover over the soil all support worm populations. Some farmers are even reintroducing earthworm species into degraded soils.

If you want to support earthworms in your own garden or yard, it's simple: stop tilling, add organic matter like compost or leaf litter, and avoid broad-spectrum pesticides. You'll be amazed at what shows up in your soil within a season.

The earthworm's story reminds us that some of the most consequential work on Earth happens in complete darkness, requiring no recognition and offering no fanfare. These creatures have been restructuring soil for over 600 million years. We're only now beginning to understand just how crucial they are—both to agriculture and to our planet's ability to handle the climate crisis.

For more on how other unobtrusive organisms are reshaping our world in unexpected ways, check out our article on why bioluminescent plankton are disappearing from our oceans and what it means for marine food webs.