Greenland’s Glaciers Retreat Twice as Fast in Two Decades

A recent study has revealed that the retreat rate of Greenland’s peripheral glaciers has doubled over the past two decades. Conducted by researchers from Northwestern University and the University of Copenhagen, the research spans from 1890 to 2022, providing the most comprehensive analysis of Greenland’s outlying glaciers to date. By integrating satellite images with a unique archive of historical aerial photographs, scientists have documented a significant acceleration in glacier retreat during the 21st century.

The study highlights that Greenland’s thousands of peripheral glaciers, separate from the massive central ice sheet, are now experiencing rapid retreat. Researchers utilized satellite imagery alongside historical photographs to assess changes in the lengths of over 1,000 glaciers along Greenland’s coastline. Although these glaciers have been retreating for much of the last century, the rate of retreat has markedly increased in recent years.

According to the findings, the pace of glacial retreat in the 21st century is now twice that of the previous century. This trend is observed across various climates and topographical features of Greenland, including some of Earth’s northernmost glaciers.

Impact of Climate Change on Glacier Dynamics

The research attributes this acceleration in glacier retreat primarily to climate change. As temperatures rise, glaciers across Greenland respond rapidly, underscoring the urgent need to address global warming. While the effects of climate change on the Greenland Ice Sheet, which covers approximately 80% of the country, have been widely studied, the fluctuations of peripheral glaciers remain less documented. This gap in knowledge is partly due to a lack of observational data prior to the advent of Earth-observing satellites in the 1970s.

A significant breakthrough occurred about 15 years ago when forgotten aerial photographs of Greenland’s coastline were rediscovered in a castle outside Copenhagen. These images, now preserved in the Danish National Archives, provided a foundation for researchers to reconstruct the historical data of the glaciers. The research team digitized thousands of aerial photographs taken from open-cockpit planes and collected contemporary imagery from multiple satellites. They also employed geo-referencing techniques to accurately position the photographs on the globe.

Mapping Historical Glacier Extents

As glaciers grow and subsequently retreat, they leave behind terminal moraines—sediment deposited by the glaciers. Identifying these moraines allowed researchers to map the historical extents of glaciers prior to the first aerial photographs taken in the early 1930s. By using imagery from the late 20th century as a baseline, the team calculated the percentage of glacier length lost over the past two decades.

The findings indicate that glaciers in southern Greenland have lost an average of 18% of their lengths, while those in other regions have experienced reductions of between 5% and 10%. As global temperatures continue to rise, understanding the implications of these melting glaciers is essential, particularly regarding rising sea levels and the availability of fresh water.

The full research is published in the journal Nature Climate Change, titled “Greenland-wide accelerated retreat of peripheral glaciers in the twenty-first century.” This study not only advances our understanding of climate impacts on glacial dynamics but also emphasizes the critical need for concerted efforts to mitigate climate change’s effects.

Dr. Tim Sandle, an expert in science journalism, has noted the importance of these findings in the broader context of environmental changes facing our planet.