Bogs are found on every continent except Antarctica, but they concentrate heavily in the cool, wet regions of the Northern Hemisphere. Canada, Russia, Scandinavia, Ireland, Scotland, and the northern United States hold the vast majority of the world’s bog area. Globally, peatlands (the broader category that includes bogs) cover about 6.75 million square kilometers, roughly 5% of Earth’s land surface.
The Largest Bog Regions on Earth
Western Siberia is home to the single greatest concentration of bogs anywhere on the planet. The West Siberian Plain alone contains 592,440 square kilometers of peatland, about 15% of all peatland on Earth and 12% of the global peat carbon stock. Within that vast lowland sits the Great Vasyugan Mire, the world’s largest individual peatland complex, stretching across roughly 55,000 square kilometers of largely uninhabited terrain. For perspective, that’s bigger than Denmark.
Canada ranks as the other global heavyweight. The Hudson Bay Lowlands, the Mackenzie River basin, and much of northern Alberta and Manitoba are blanketed in bog. Finland and Sweden together hold enormous tracts, as does Norway. In the British Isles, Ireland and Scotland are disproportionately bog-rich relative to their size. Ireland’s midlands were once dominated by raised bogs, and blanket bogs still cover large stretches of western and upland landscapes in both countries. Smaller but ecologically important bogs also exist in the Baltic states, northern Germany, Poland, and parts of the northern United States, particularly Minnesota, Michigan, Wisconsin, and Maine.
In the Southern Hemisphere, bogs are rarer but not absent. Patagonia, New Zealand’s South Island, and parts of Southeast Asia (especially the tropical peatlands of Borneo and Sumatra) all contain significant peat-forming wetlands, though tropical peatlands differ from the classic cold-climate bog.
What Makes a Landscape Form a Bog
Bogs need two things: consistent rainfall that exceeds evaporation, and poor drainage. They form in places where water sits on or near the surface year-round, creating waterlogged, oxygen-starved conditions that prevent dead plant material from fully decomposing. Over centuries, that partially decayed vegetation compresses into peat.
A true bog is “ombrotrophic,” meaning it gets all its water and nutrients from rain and snow rather than from streams or groundwater. This makes bog water extremely acidic and nutrient-poor. The pH of near-surface water in a typical bog ranges from 3.4 to 4.0, roughly as acidic as orange juice. Decomposition is so slow that over 99% of a bog’s nitrogen is locked in the peat itself, unavailable to plants. This harsh chemistry is what gives bogs their distinctive look: dominated by sphagnum moss, low-growing heather-family shrubs, sedges, and scattered stunted trees rather than lush vegetation.
Raised Bogs vs. Blanket Bogs
Not all bogs look the same. The two main types form in different landscapes and have distinct shapes.
Raised bogs develop in lowland basins or former lake beds. Over thousands of years, sphagnum moss grows upward from the center, creating a dome of peat that rises above the surrounding water table. These bogs are common across the midlands of Ireland, the Baltic region, and parts of Scandinavia and Canada. Because they’re elevated above groundwater influence, they depend entirely on rainfall.
Blanket bogs form in upland areas with high rainfall and cool temperatures. Instead of filling a basin, peat spreads across the landscape like a blanket, draping over gentle slopes and hilltops. On Dartmoor in southwest England, blanket bog covers the gentle slopes above 400 meters elevation, with peat at least half a meter thick mantling the open moor. Blanket bogs are especially characteristic of western Ireland, Scotland, Wales, and Norway, where oceanic climates deliver rain on 200 or more days per year.
Why Bogs Favor Cool, Wet Climates
The global distribution of bogs follows a clear climatic pattern. They cluster between roughly 50°N and 70°N latitude, in the boreal and subarctic zones, because these regions combine three ideal conditions: cool temperatures that slow decomposition, abundant precipitation, and flat or gently rolling terrain left behind by glaciers. The retreating ice sheets of the last glacial period carved out countless shallow depressions and disrupted drainage patterns, creating the waterlogged basins where many bogs began forming 8,000 to 12,000 years ago.
Further south, bogs become restricted to mountains or coastal zones where altitude or maritime weather recreates those cool, wet conditions. That’s why you find bogs in the highlands of Scotland and the mountains of Dartmoor but not in the warmer, drier lowlands of central England or southern France.
Carbon Storage and Global Importance
Bogs punch far above their weight in the global carbon cycle. Despite covering just 5% of Earth’s land surface, peatlands store an estimated 942 billion tonnes of carbon, roughly double the carbon held in all the world’s forests combined. They have the highest carbon storage capacity per unit area of any terrestrial ecosystem.
The rate at which bogs pull carbon from the atmosphere varies by region. Boreal and subarctic peatlands in Canada and Siberia accumulate carbon relatively slowly, around 0.8 tonnes of CO₂ equivalent per hectare per year. Temperate blanket bogs in the UK accumulate carbon much faster, at roughly 11.8 tonnes of CO₂ equivalent per hectare per year. Present-day measurements of active sphagnum moss growth in temperate bogs show sequestration rates around 9 tonnes of CO₂ equivalent per hectare annually.
This carbon storage is why bog destruction matters so much. When bogs are drained for agriculture, peat extraction, or development, the exposed peat oxidizes and releases its stored carbon as CO₂. Protecting and restoring bogs in Canada, Russia, Scandinavia, and the British Isles is now a significant part of international climate strategies, because keeping that carbon locked in waterlogged peat is far easier than trying to recapture it once it’s in the atmosphere.