A recent study by researchers at NASA’s Jet Propulsion Laboratory has brought to light that Greenland ice melting is occurring at a much faster rate than previously thought. The study, published in Nature, indicates that the Greenland Ice Sheet has lost 21% more mass in the past four decades than was estimated earlier, raising concerns about future ocean circulation and climate impacts.
The comprehensive analysis, spanning from 1985 to 2022, used nearly a quarter million pieces of satellite data to assess glacier positions across Greenland, shedding light on the alarming trend of Greenland ice melting. It found that out of the 207 glaciers studied, 179 have retreated significantly, while only one showed a slight advancement. The majority of the ice loss occurred below sea level in fjords around Greenland’s periphery, areas previously filled with ancient glacial ice.
Although the calving and retreat of ice from these glaciers have not directly contributed to the rise of sea levels due to their position in the water, the accelerated ice flow from higher elevations has had an impact. Chad Greene, a glacier scientist at JPL and the study’s lead author likened the retreat of glacier ice to “pulling the plug out of the fjord,” which speeds up the drainage of ice into the ocean.
Historically, the Greenland Ice Sheet has significantly contributed to rising global sea levels. Estimates by the Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) and the Intergovernmental Panel on Climate Change suggested that between 1992 and 2020, the ice sheet lost around 5,390 billion tons, raising the global mean sea level by approximately 0.531 inches. The new study adds to this understanding by quantifying the ice lost due to the retreat of terminal glaciers, which needed to be accounted for in the IMBIE assessment.
The additional ice loss represents a substantial influx of freshwater into the ocean. This could weaken the Atlantic Meridional Overturning Circulation, a crucial part of the global oceanic “conveyor belt.” Such changes in ocean salinity could affect weather patterns worldwide and various ecosystems.
The study reveals that while Greenland’s ice extent remained stable from 1985 to 2000, a marked recession began and continues to date. Notably, the glacier Zachariae Isstrom in northeast Greenland experienced the most significant loss, followed by Jakobshavn Isbrae and Humboldt Gletscher.
This large-scale pattern of retreat, linked to each glacier’s sensitivity to seasonal warming, suggests that those most affected in summer will likely face the greatest impact from climate change in the coming years.
JPL cryosphere scientist Alex Gardner, a co-author of the paper, emphasized the importance of this study in providing a systematic and comprehensive view of Greenland’s ice sheet. This perspective is crucial for understanding the broader implications of glacial retreat and its contribution to global environmental changes.
This groundbreaking study not only enhances our understanding of the current state of the Greenland Ice Sheet but also underscores the urgency of addressing climate change and its far-reaching impacts on the planet.