Beringia, an ancient landmass, represents a prehistoric connection between continents. This vast region, now largely submerged, played a profound role in shaping global ecosystems and facilitating the dispersal of diverse life forms. Understanding Beringia’s existence and eventual disappearance provides insights into past climatic shifts and their environmental and biological consequences.
The Bering Land Bridge: Location and Formation
Beringia was an expansive area connecting what is now northeastern Siberia and Alaska, extending into parts of the Yukon and Northwest Territories in Canada. This land bridge emerged during periods of global glaciation when massive ice sheets locked up vast amounts of Earth’s water, causing sea levels to drop. During the Last Glacial Maximum (LGM), approximately 26,000 to 19,000 years ago, global sea levels were about 120 to 130 meters (300 to 400 feet) lower than today, exposing the shallow continental shelf beneath the Bering and Chukchi seas.
This exposed landmass was immense, reaching up to 1,000 kilometers (620 miles) wide and stretching over 1,600 kilometers (1,000 miles) from north to south. Its total area was approximately 1.6 million square kilometers (620,000 square miles), comparable in size to the Canadian provinces of British Columbia and Alberta combined, or even as large as Australia. The most recent emergence of the Bering Land Bridge began around 38,000 years ago, with some studies suggesting its full exposure around 35,700 years ago. This unglaciated plain served as a unique continental link for thousands of years.
Beringia’s Ancient Ecosystem and Migratory Significance
The environment of Beringia during its exposure was distinct from surrounding glaciated regions. It was predominantly a “mammoth steppe” or “steppe-tundra,” a vast, dry grassland ecosystem rich in grasses and other herbaceous plants. This landscape was largely ice-free due to its arid climate, which prevented significant snow accumulation despite cold temperatures. This unique biome supported large mammals, often referred to as megafauna, adapted to grazing on the abundant vegetation.
Herds of woolly mammoths, steppe bison, horses, and caribou roamed these plains, alongside predators such as scimitar cats, American lions, and giant short-faced bears. Beringia served as a pathway for the dispersal of species between Asia and North America. This land bridge facilitated the migration of early humans, known as Paleo-Indians, from Siberia into the Americas. This movement involved humans following large animal herds across the exposed land, gradually populating the North American continent. Evidence suggests human presence in interior Alaska and the Yukon as early as 14,000 years ago, following these ancient routes.
The Submergence of Beringia
Beringia disappeared as Earth’s climate began to warm at the end of the last ice age. Starting around 18,000 years ago, vast continental glaciers across the Northern Hemisphere began to melt. This massive meltwater input caused global sea levels to rise steadily. As sea levels climbed, the low-lying plains of Beringia were gradually inundated by encroaching waters.
By approximately 11,000 years ago, the land bridge was completely submerged, forming the Bering Strait that exists today. This submergence re-established the water connection between the Pacific and Arctic Oceans, effectively severing the terrestrial link between Asia and North America. The submergence of Beringia led to environmental shifts, including changes in ocean currents and the expansion of shrub tundra in previously dry regions. Today, only a few islands, such as the Diomede Islands and St. Lawrence Island, remain as visible remnants of this once-expansive prehistoric landscape.