What is peatland restoration and why does it matter for climate?

The short answer

Peatlands are waterlogged landscapes, bogs, fens, swamps, where dead plants pile up faster than they decay, locking carbon into layers of soil called peat. They cover just 3% of the world's land surface but hold roughly twice as much carbon as every forest on Earth combined. When left wet, peat keeps that carbon buried. When drained for farming, forestry, or fuel, it starts to break down and release carbon that has often been sitting there for thousands of years. Peatland restoration is the practice of rewetting and repairing these drained landscapes so they stop leaking carbon and go back to storing it.

A carbon store most people have never heard of

Peat forms in a strange, almost accidental way. In waterlogged ground, oxygen can't reach dead plant matter fast enough for it to fully decompose. So instead of rotting away and releasing its carbon back into the air, the plant material just piles up, century after century, compressing into peat. Some peat deposits have been forming since the last ice age.

The scale of what's stored this way is easy to underestimate. Peat soils hold more than 600 billion tons of carbon, close to half of all the carbon stored in soil worldwide, according to the IUCN.¹ That's more than the carbon held in all of the planet's forest biomass put together, despite peatlands covering a tiny sliver of land by comparison.

The Congo Basin surprise

In 2017, a research team led by Greta Dargie and Simon Lewis, working across the Republic of Congo and the Democratic Republic of Congo, mapped a peatland complex nobody had previously measured: the Cuvette Centrale, hidden beneath swamp forest in the central Congo Basin. Reaching the field sites meant traveling by boat, then wading and hiking through waist-deep water and mud for days.

What they found reshaped scientists' understanding of tropical carbon storage. The Cuvette Centrale peatlands span roughly 145,500 square kilometers, an area larger than England, and hold an estimated 30 billion tons of carbon underground, according to their study published in Nature.⁴ That single discovery increased the best global estimate of tropical peatland carbon stocks by more than a third. It's also, researchers noted, roughly equivalent to 20 years of United States carbon emissions, sitting quietly under one of the least-studied forests on the planet.

What happens when peatlands are drained

Drain a peatland, for farmland, forestry, or peat extraction, and the whole system changes. Oxygen reaches all that stored organic matter, microbes get to work breaking it down, and centuries of buried carbon starts escaping as CO₂. A peatland that spent thousands of years pulling carbon out of the atmosphere becomes a source of emissions instead.

Globally, damaged and drained peatlands emit roughly 2 billion tons of CO₂ every year, close to 5% of all human-caused greenhouse gas emissions, according to the IUCN, despite covering well under 1% of the planet's land surface.¹ Drained peat is also dangerously flammable. When Indonesian peat swamp forests burned in 2015, the fires released an estimated 16 million tons of CO₂ a day, more than the entire daily output of the US economy, according to IUCN figures.¹

How does peatland restoration work?

The core idea behind peatland restoration is simple, get the water table back up. Most restoration starts with blocking the drainage channels that were cut to dry the land out in the first place, using peat dams, timber, plastic piling, or simply packed local material, so water backs up and the ground stays saturated again.

On sites where the peat has dried out too much for mosses to recolonize naturally, restoration teams use a method called the moss layer transfer technique. Fragments of living sphagnum moss, the plant most responsible for building peat in the first place, are harvested from a healthy donor site and spread across the bare, rewetted surface. Only the top few centimeters of moss are taken, and a site can typically supply enough material to restore an area ten to twelve times its own size, since the harvested patch regrows within several years.⁵

Why does peatland restoration matter for climate policy?

Peatland restoration rarely gets the same attention as tree planting, but the numbers argue it should. The UN Environment Programme estimates that protecting, restoring, and sustainably managing peatlands worldwide could cut global emissions by roughly 800 million metric tons a year, comparable to Germany's entire annual output.⁶ In the UK, the IUCN UK Peatland Programme has set a target of bringing two million hectares of peatland into good condition, restoration, or sustainable management by 2040.⁵

Because peatland restoration is harder to see than a newly planted forest, they've historically been left out of a lot of climate strategy. That's changing as the scale of what they store, and can be lost if they are drained, becomes harder to ignore.

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