The Beaufort Gyre is an important ocean current system in the Arctic Ocean, located predominantly north of Alaska and Canada. This large, wind-driven current influences the polar region and has potential connections to global climate patterns. Understanding this gyre is becoming increasingly important as the Arctic experiences rapid environmental changes.
Understanding the Beaufort Gyre
The Beaufort Gyre is an anticyclonic (clockwise) current in the Canadian Basin of the Arctic Ocean. This immense current is driven primarily by persistent winds associated with a high-pressure system known as the Beaufort High. The Earth’s rotation also influences its movement, contributing to its circular pattern.
Within this circulation, the gyre acts as the Arctic Ocean’s largest reservoir of freshwater. This freshwater accumulates at its center due to the balance between pressure and the Coriolis effect. As of 2021, the Beaufort Gyre held approximately 22,000 cubic kilometers of freshwater, representing an increase of about 23% since 2003. This volume, roughly equivalent to all of the North American Great Lakes combined, forms a dome that has expanded vertically by about 15 centimeters since 2002.
Its Role in Arctic Dynamics
The Beaufort Gyre performs several functions within the Arctic ecosystem. It stores and redistributes freshwater from various sources, including melting sea ice, glacial melt, river runoff, and water flowing in from the Bering Sea. This accumulation prevents the immediate release of this freshwater into the North Atlantic, regulating its flow over decades.
The gyre influences sea ice formation and movement. It acts as a trap, corralling vast amounts of sea ice in its clockwise swirl, which historically allowed the ice to thicken over several years. This process contributed to the formation of thick, multi-year sea ice that once covered large parts of the Arctic Ocean. The gyre’s influence also extends to nutrient distribution and marine life by affecting primary productivity.
Beyond its local effects, the Beaufort Gyre functions as a climate regulator for high-latitude regions. By sequestering freshwater and influencing sea ice, it modulates ocean properties within the Arctic and impacts the transport of heat globally. It helps maintain equilibrium in the polar environment by keeping freshwater at the surface, which in turn helps protect the sea ice from further melting.
Observed Changes and Underlying Causes
Changes have been observed in the Beaufort Gyre in recent decades, particularly an increased accumulation of freshwater and alterations in its circulation. Since the 1990s, the gyre has gained approximately 8,000 cubic kilometers of freshwater, nearly twice the volume of Lake Michigan. This increase in freshwater content has led to a noticeable freshening of the gyre.
The primary causes of these changes are linked to altered wind patterns and the accelerating melt of Arctic sea ice. The decades-long decline of summer and autumn sea ice cover has left the Beaufort Gyre more exposed to the wind. This increased exposure has caused the gyre to spin faster, intensifying its clockwise current and trapping more freshwater within its circulation. Persistent westerly winds, which have continued for over 20 years, have further contributed to the increased speed and size of the gyre, preventing the accumulated freshwater from leaving the Arctic Ocean.
Scientists are concerned about the potential for “release events” of this stored freshwater. While the gyre has shown a recent transition to a more stable state, the thinning of the cold halocline layer could still enable a future release. This cold halocline layer normally isolates warmer, saltier Atlantic water at depth. It has thinned due to reduced input of cold, salty water from the Pacific Ocean and increased mixing from the eastern Beaufort Sea.
Wider Environmental Consequences
A sudden release of the Beaufort Gyre’s stored freshwater into the North Atlantic could have major environmental consequences. This influx of freshwater has the potential to disrupt the Atlantic Meridional Overturning Circulation (AMOC), a large system of ocean currents that transports heat throughout the globe. If the AMOC were to slow down, it could lead to significant temperature shifts, potentially causing a temporary but noticeable cooling in Western Europe, despite overall global warming trends.
Such a release could also affect Arctic marine ecosystems. Changes in ocean stratification, where layers of different densities form, could occur. This altered stratification might impact the mixing of nutrients and organic material in the ocean, potentially affecting the marine food chain and wildlife within the Arctic. Continued sea ice decline could also be exacerbated if the delicate balance maintained by the gyre is disturbed. Scientists are actively researching these potential impacts, recognizing that changes in Arctic Ocean circulation could have broader climate implications beyond the polar region.