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Study Reveals Dynamic Behavior of Greenland’s Glaciers
Although the term ‘glacial’ typically conjures images of slow, relentless movement, recent research indicates that glaciers exhibit rapid fluctuations in their movement on a daily and even hourly basis. These changes are closely linked to varying factors such as air temperature, rainfall, and tidal cycles.
A team of researchers, including experts from Hokkaido University in Japan, has conducted an extensive study on a Greenland glacier over six summer seasons. Their work focused on mapping the glacier’s movements in relation to local weather patterns and tidal influences, providing new insights into the mechanics behind glacier flow. The findings have been published in the journal The Cryosphere.
“Understanding short-term speed variations is essential for grasping the physical processes that govern glacial motion,” stated Shin Sugiyama, the study’s lead author from Hokkaido University. He emphasized that research on Greenland’s tidewater glaciers, particularly those near their calving fronts, remains limited. “Investigating glacier dynamics at the ocean boundary is vital for assessing both current and future ice sheet mass loss.”
The research team selected Bowdoin Glacier, known as Kangerluarsuup Sermia in Greenlandic, which terminates in Bowdoin Fjord in northwestern Greenland. This glacier, like many in the region, has been thinning and retreating rapidly since 2008.
To gather data, researchers installed GPS devices at various points along the glacier, from 500 meters to four kilometers from the calving front. They also deployed sensors to monitor local air temperature and rainfall, collecting a comprehensive dataset over a 90-day period spanning 2013 to 2019.
The study found that the glacier exhibited daily and twice-daily acceleration patterns. The initial increase in speed is attributed to daily meltwater flows resulting from rising daytime temperatures. The second spike, observed near the glacier’s terminus, aligns with the tidal movements occurring twice daily. Notably, peak speeds were consistently recorded either at or just before low tide.
In addition to these daily variations, the glacier experienced one to two significant acceleration events each year, often correlating with extreme weather conditions such as unusually high temperatures or heavy rainfall.
“The strong relationship between ice speed and temperature highlights the critical role of meltwater production in regulating the dynamics of Greenland’s outlet glaciers,” Sugiyama remarked. The research indicated that glacier flow accelerated significantly when temperatures surpassed 10 degrees Celsius, with a mere two-hour lag between maximum temperatures and peak speeds, demonstrating the rapid drainage of meltwater to the glacier bed.
However, the relationship between heavy rainfall and glacier speed presented a more intricate picture. Researchers believe this complexity arises from the interplay between tidal forces and the efficiency of sub-glacial drainage systems.
“Our findings provide crucial insights into the dynamics of tidewater glaciers and are significant for understanding the future developments of the ice sheet as climatic conditions continue to change in Greenland,” Sugiyama concluded.
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