The Arctic coastal tundra is a unique and expansive biome. This region, found at the northernmost edges of continents, holds significant global importance. Its distinctive features and the life it supports are linked to the planet’s broader ecological systems, making it a subject of scientific interest.
Defining Arctic Coastal Tundra
The Arctic coastal tundra is a treeless biome situated along the coastlines of the Arctic Ocean. It is defined by extremely cold temperatures, a short growing season, and permafrost, which is ground that remains frozen for at least two consecutive years. Winter temperatures can drop to -30°C, while summer mean temperatures are around 4.5°C, with a growing season from mid-June through August.
This environment is a low, flat, and often boggy coastal plain, ranging from 0 to 150 meters in elevation. The underlying permafrost contains high ice content, including ice wedges and pingos, which are mounds of earth-covered ice. Proximity to the ocean influences its climate, making it wetter and foggier than inland tundra. This biome is distributed across northern Alaska, Canada, Siberia, and Greenland.
Life in the Extreme
Life in the Arctic coastal tundra exhibits adaptations to its harsh conditions. The flora consists of low-growing plants such as mosses, lichens, sedges, grasses, and dwarf shrubs like dwarf birch, willow, and northern Labrador tea. These plants possess shallow root systems, growing only in the “active layer” of soil that thaws during the brief summer. Many can photosynthesize efficiently in the cold, indirect light of the Arctic summer.
The fauna includes polar bears, caribou, musk oxen, and arctic foxes, along with a diverse array of migratory birds. Caribou herds utilize the tundra for calving, taking advantage of nutritious plants during summer. Animals survive the cold through adaptations like thick fur, while many bird species migrate thousands of miles to warmer regions for winter, returning to the tundra for breeding and to exploit abundant summer food sources. The tundra’s wetlands provide crucial breeding grounds for millions of waterbirds, including ducks, geese, loons, and shorebirds, offering abundant food and fewer predators.
Ecological Significance
The Arctic coastal tundra plays a significant role in global ecosystems. It functions as a carbon sink, storing vast quantities of organic carbon within its permafrost, accumulated over thousands of years. This frozen carbon reservoir represents more than half of the global terrestrial carbon. The tundra also contributes to global climate regulation through the albedo effect, where snow and ice-covered surfaces reflect solar radiation back into space, helping to cool the Earth.
Beyond its climate-regulating functions, the tundra provides important habitat for wildlife. It serves as an important breeding ground for millions of migratory birds. Coastal areas also support marine mammals like beluga whales and walruses. Indigenous communities, such as the Inuit and Saami, have lived in and relied on the Arctic for millennia, with their cultural identity and traditional livelihoods intertwined with the tundra’s ecosystems.
Responding to Change
The Arctic coastal tundra is experiencing significant impacts from global climate change. A primary effect is the thawing of permafrost. As permafrost thaws, previously frozen organic matter decomposes, releasing greenhouse gases like carbon dioxide and methane into the atmosphere, which further accelerates warming. This process can transform the tundra from a carbon sink into a net carbon source.
Permafrost thaw also leads to ground subsidence and coastal erosion. Land can sink as the ice within the permafrost melts, creating irregular surfaces and depressions that fill with water to form thermokarst lakes. Coastal erosion rates are accelerating, with some areas losing up to five meters of coastline annually, exacerbated by reduced sea ice buffering and increased storm surges. These changes directly impact plant and animal life through habitat loss and altered migration patterns. For instance, melting permafrost can drain wetland breeding sites for birds, and changes in vegetation patterns affect grazing animals like caribou.