The quiet giants of carbon storage

A peat bog does not look like much at first sight. Low mosses, a few sedges, perhaps a pool of dark water. It has none of the drama of a rainforest or a coral reef. Yet under your feet lies one of the most important ecosystems on Earth for the climate.

Plants that do not rot

Peat is made of plants that never fully decayed. The Global Peatlands Initiative describes it as partially decayed plant material that accumulates under waterlogged conditions over long periods of time.

Normally, when a plant dies, fungi and bacteria break it down and its carbon returns to the air. In a peatland, the ground is soaked with water all year round. As the IUCN explains, these waterlogged conditions slow decomposition so much that dead plants pile up instead, layer upon layer, forming peat.

The process is slow. But peatlands have been at it for a very long time, and the result is enormous.

A carbon store bigger than the forests

Peatlands are known to cover at least 3 percent of the world’s land surface, according to the IUCN. Yet their soils contain more than 600 gigatonnes of carbon — more than is stored in all other vegetation types, including all the world’s forests.

That is a striking comparison. Forests are usually the first thing people think of when it comes to nature storing carbon. Peatlands, small and often overlooked, hold more.

Found almost everywhere

Peatlands occur in almost every country. The Global Peatlands Initiative lists where they are found: in permafrost regions towards the poles and at high altitudes, along coasts, beneath tropical rainforest and in boreal forests. People call them by many names — bogs, fens, mires and peat swamp forests.

Some are only now being mapped. The IUCN notes that the world’s largest tropical peatland was identified beneath the forests of the Congo Basin as recently as 2017.

When the water goes

A peatland’s carbon store only stays put as long as the peat stays wet. When peatlands are drained — for farming, forestry or to dig out the peat itself — air reaches the plant material. Decomposition starts again, and the carbon that took thousands of years to accumulate escapes as carbon dioxide.

The IUCN estimates that emissions from drained peatlands amount to about 1.9 gigatonnes of CO₂-equivalent every year. Dry peat can also burn, and peat fires can smoulder underground for long periods.

Wet again

The good news is that the solution is simple to describe: keep peatlands wet. The IUCN calls for urgent action worldwide to protect, sustainably manage and restore peatlands. In practice, that means stopping new drainage and conversion to agriculture, and restoring waterlogged conditions where peatlands have already been drained — for example by blocking drainage ditches.

Gardeners can help too. Much of the compost sold for gardens has traditionally contained peat. Choosing peat-free compost leaves the carbon where it belongs: in the ground.

Why it matters

Peatlands are proof that an ecosystem does not have to be spectacular to be vital. A quiet bog, slowly growing for thousands of years, can hold more carbon than a forest. Protecting it costs little; losing it costs a great deal.