Peatlands receive a fraction of the attention forests do and store a disproportionate share of terrestrial carbon, which makes their condition unusually consequential.
What peat is
Partly decomposed plant material accumulated where waterlogging prevents full decomposition.
Which means carbon fixed by plants is not returned to the atmosphere but accumulates, over thousands of years, to considerable depth.
The accumulation rate is slow — a millimetre or so annually — which means damaged peat cannot be replaced on any relevant timescale.
The carbon stock
Peatlands cover a small percentage of land area and store a large share of soil carbon.
Which makes them the most carbon-dense terrestrial ecosystem by area, exceeding forests substantially.
Intact peatland is a net sink, accumulating carbon continuously.
Damaged peatland is a net source, and drained peatlands worldwide emit a substantial quantity annually.
What damages them
Drainage, for agriculture, forestry or development, which is the principal cause.
Once drained, oxygen reaches the peat and decomposition resumes, releasing carbon.
Extraction for horticultural growing media and, historically, for fuel.
Burning, whether managed or wildfire, which releases carbon directly and can smoulder underground for months.
Overgrazing, which removes the vegetation that maintains the surface.
And afforestation, which requires drainage and therefore causes emissions exceeding the trees' sequestration.
Beyond carbon
Water regulation, since peat holds enormous quantities and releases it slowly, which affects downstream flooding and drought.
Water quality, since damaged peat releases dissolved carbon that water treatment must remove at cost.
Distinctive biodiversity, including specialist plants, invertebrates and breeding birds found nowhere else.
And archaeological preservation, since waterlogged anaerobic conditions preserve organic material for millennia.
Restoration
Conceptually straightforward — restore the water table.
Which is achieved by blocking drainage ditches, removing trees where they were planted, and reprofiling eroded surfaces.
Vegetation recovery follows, and emissions reduce measurably within years.
Full recovery of carbon accumulation takes considerably longer, and stopping the emissions is the immediate gain.
The techniques are established and the cost per unit of avoided emissions compares favourably with many alternatives.
Horticultural peat
Extraction for growing media continues, and several countries have moved toward bans on retail sale.
Peat-free alternatives have improved substantially and were genuinely inferior for some uses in earlier formulations.
Which means checking that compost is peat-free is a small individual action with a direct link to the outcome, and the labelling can be ambiguous.
Tropical peatlands
Store enormous quantities of carbon and have been extensively drained for plantation agriculture.
Which has caused very large emissions and recurring severe fires with regional air quality consequences.
Rewetting and restoration efforts exist and operate against strong economic pressure for the land.
Why they get less attention
They are not visually appealing in the way forests are, they are frequently remote, and the carbon is invisible.
Which is a communication problem rather than a scientific one, and the evidence for their importance is not in dispute.
Types
Bogs receive water only from precipitation, which makes them nutrient-poor and acidic.
Fens receive groundwater, which makes them less acidic and more nutrient-rich, supporting different vegetation.
Which means restoration approaches differ, since restoring bog hydrology and fen hydrology are different problems.
Blanket bog, forming over large areas in wet cool climates, is globally restricted in distribution and disproportionately concentrated in a few countries.
Monitoring
Water table depth is the key indicator, since it determines whether peat is accumulating or oxidising.
Which is measured with simple wells and increasingly with automated loggers.
Satellite methods measuring surface motion can detect peat subsidence and swelling, which indicates condition over large areas.
Policy
Peatland restoration appears in national climate strategies in several countries, with funding attached.
Which reflects the emissions arithmetic, since drained peatland emissions are a substantial share of land-use emissions in countries with extensive peat.
Accounting rules for these emissions have been developed and are applied inconsistently.
Sphagnum
The genus of mosses that builds most bog peat.
It acidifies its surroundings, holds many times its weight in water, and resists decomposition.
Which means it engineers the conditions that allow peat to form, and its recovery is the indicator of successful bog restoration.
Reintroduction of sphagnum to bare peat surfaces is a standard restoration technique.
Grouse moor management
In some regions, upland peat is managed by burning to produce habitat for game.
Which is contested — evidence on the effects of burning on peat condition, water quality and carbon has been argued in both directions, with the weight favouring negative effects.
Regulation restricting burning on deep peat has been introduced in some jurisdictions.
Visiting them
Peatland surfaces are fragile and vulnerable to trampling, which causes erosion that spreads.
Which is why boardwalks exist on visited sites, and staying on them genuinely matters here more than on most terrain.
Access to restoration sites is frequently permitted and the paths are there for the peat rather than for convenience.