Tundra covers roughly 10 percent of Earth’s surface, spread across three distinct types: Arctic tundra stretching across the far north of North America, Europe, and Asia; alpine tundra found on high mountains around the world; and a small pocket of Antarctic tundra on islands near the southern continent. Most of it sits between 60° and 75° north latitude, but tundra can appear anywhere conditions are too cold and windy for trees to survive.
Arctic Tundra: The Largest Belt
The biggest stretch of tundra on Earth forms a continuous band across the top of the Northern Hemisphere, running along the Arctic coasts of North America and Eurasia and the coastal margins of Greenland. Much of Alaska and about half of Canada fall within this zone, including vast areas of the Northwest Territories, Nunavut, and northern Quebec. In Europe, Arctic tundra covers northern Scandinavia (particularly Norway’s Finnmark plateau and parts of northern Sweden and Finland) and extends across Iceland’s interior highlands.
The largest single expanse sits in Russia. Siberian tundra stretches from the Kola Peninsula in the west all the way to the Chukchi Peninsula in the east, covering millions of square kilometers north of the taiga forest belt. These North American and Eurasian tundra regions were once connected by a land bridge between Siberia and Alaska, which is why many of the same plant and animal species appear on both continents.
What Defines the Southern Boundary
The northern tree line is the single most important geographic marker for where tundra begins. This boundary circles all of Earth’s northern landmasses for more than 8,300 miles, forming the planet’s largest ecological transition zone. North of it, cold air, frozen soils, and limited sunlight prevent trees from growing. South of it, boreal forest (taiga) takes over.
The tree line isn’t a clean, straight border. It loops north and south depending on local terrain, ocean currents, and wind patterns. In some places the shift from forest to tundra happens gradually over dozens of miles, with stunted, scattered trees giving way to open ground. In others, the transition is sharp enough to see from a plane. Near the Arctic Circle in northern Alaska, for example, forests begin giving way to tundra within a relatively narrow band.
Alpine Tundra on Mountains
Alpine tundra accounts for about 3 percent of Earth’s land surface and appears on mountains worldwide, wherever elevation pushes conditions above the tree line. The altitude where this happens varies enormously depending on latitude and local climate. In the Himalayas, the Southern Rockies, and California’s Sierra Nevada, alpine tundra begins around 3,300 to 3,600 meters (roughly 10,800 to 11,800 feet). On the Lesotho Plateau in South Africa, it starts much lower, around 2,300 meters. In the Andean steppe of Argentina, tundra conditions can appear as low as 1,650 meters because of the region’s dry, cold winds.
Other notable alpine tundra locations include the European Alps, the Tibetan Plateau (one of the world’s largest high-altitude tundra zones), the Andes above the tree line in Peru and Bolivia, and scattered peaks in East Africa like Mount Kilimanjaro and Mount Kenya. Although these alpine environments share many features with Arctic tundra, including low-growing vegetation, harsh winds, and a short growing season, they receive more sunlight and lack the months-long polar darkness that defines the far north.
Antarctic Tundra
Antarctica itself is mostly covered by ice sheets too thick and cold for even tundra vegetation. But small patches of Antarctic tundra exist on the continent’s coastal fringes and on nearby sub-Antarctic islands. The South Shetland Islands, particularly King George Island, support herb tundra communities of mosses, lichens, and a few hardy flowering plants in areas exposed by retreating glaciers. Other sub-Antarctic islands with tundra-like vegetation include South Georgia, the Kerguelen Islands, and the Falkland Islands. These pockets are tiny compared to Arctic tundra, but they represent the only tundra ecosystems in the Southern Hemisphere outside of high mountain ranges.
Why These Boundaries Are Shifting
Tundra is not a fixed zone. Between 1985 and 2020, boreal tree cover expanded by about 844,000 square kilometers, a 12 percent increase, and the tree line shifted northward by roughly 0.4 degrees of latitude. That’s a meaningful change over just 35 years. The strongest gains in tree cover occurred between 64° and 68° north, right at the border where forest meets tundra, supporting the pattern of a steady poleward creep.
This means tundra is shrinking from its southern edge as warming temperatures allow shrubs and then trees to colonize ground that was previously too cold. The expansion is happening across the entire northern tree line, not just in isolated spots. At the same time, small net losses in forest cover appeared at the southern edge of the boreal zone (47° to 52° north), suggesting the whole system is sliding northward. For the tundra itself, the practical result is that the biome’s total area is gradually contracting as forests advance into territory that has been treeless for thousands of years.