A large part of the ice loss is due to glaciers speeding up and transporting more ice from land into the ocean, as at Jakobshavn Isbræ in Greenland (pictured).
Photo Credit: Johan Nilsson
Scientific Frontline: Extended "At a Glance" Summary: Polar Ice Mass Balance
The Core Concept: A comprehensive synthesis of satellite data reveals that the Greenland and Antarctic ice sheets lost a combined 11,309 billion metric tons of ice between 1979 and 2023.
Key Distinction/Mechanism: Ice mass is lost dynamically when ice shelves thin, reducing their buttressing effect and allowing glaciers to accelerate their transport of land ice into the ocean, a process responsible for 84 percent of the total mass loss.
Origin/History: The IMBIE (Ice Sheet Mass Balance Inter-comparison Exercise) study aggregated data from 27 satellite missions, with records dating back to 1972 for Greenland and 1979 for Antarctica.
Major Frameworks/Components:
- Greenland Mass Loss: Transitioned from near equilibrium in the 1970s to a deficit of 264 billion metric tons annually in the 2010s, primarily driven by elevated summer temperatures and surface melting.
- Antarctic Mass Loss: Increased from 48 billion metric tons annually in the 1980s to 202 billion metric tons in the 2010s, primarily concentrated in West Antarctica due to basal melting by warm seawater.
- Methodological Synthesis: The study integrated 42 independent estimates combining satellite altimetry, gravimetry, and ice velocity with regional climate modeling to distinguish between surface processes and dynamic ice transport.
- Sea Level Contribution: The combined ice loss has contributed approximately three centimeters to the global mean sea-level rise since 1979.
Branch of Science: Earth Science, Physical Geography, Climatology, Glaciology, and Oceanography.
Future Application: The aggregated dataset provides crucial long-term trend analysis, enabling more accurate parameterization of future climate models and improving the reliability of global sea-level rise forecasts.
Why It Matters: The sustained and accelerating loss of polar ice sheets directly drives sea-level rise, increasing the risk of coastal flooding and erosion globally, with regional impacts varying due to factors like post-glacial rebound and the gravitational redistribution of seawater.
Since the 1970s, 11 trillion metric tons of ice have been lost from Greenland and Antarctica, according to a new international study based on data from a range of satellite surveys. This is enough water to form a layer 25 meters thick if spread out across the entire area of Sweden.
An international team of researchers has produced the most comprehensive picture to date of ice loss from Greenland and Antarctica. Between 1979 and 2023, these two ice sheets together lost 11,309 billion metric tons of ice, which corresponds to just over 3 centimeters of global sea-level rise.
“It can be difficult to get a sense of just how much ice we’re actually talking about. If the ice were spread out as water over the entire area of Sweden, it would form a layer 25 meters thick. The volume of water is equivalent to around 75 times the volume of Lake Vänern,” says Johan Nilsson, a researcher in physical geography at Uppsala University, who contributed satellite-based data to the study.
Five Decades of Satellite Data
The new international compilation is based on data from 27 satellite missions and reaches back as far as 1972 for Greenland and 1979 for Antarctica. The two major polar regions have been monitored through 2023. The researchers combined satellite measurements of ice height, the gravitational field, and the speed at which the ice moves with regional climate models to distinguish between processes on the ice surface and changes in ice dynamics. In total, the study is based on 42 independent estimates: 23 for Greenland and 19 for Antarctica.
“The amount of ice can both increase and decrease from one year to the next due to natural variations in the climate system. It is only when we track developments over several decades that the long-term trend becomes clear. Rather than individual research teams presenting their own separate figures, we have compiled the results into a single set of figures. This gives us much more reliable results that can improve future climate models and sea-level rise forecasts,” says Nilsson.
The Ice Sheets Are Losing More and More Ice
These extended time series make it possible to place current developments in a historical context and show just how rapidly the situation has changed.
In Greenland, the ice sheet was close to balance during the 1970s, when the amount of snowfall roughly equaled the amount of ice lost. During the 1980s, the average loss was around 60 billion metric tons per year. Three decades later, in the 2010s, it had risen to 264 billion metric tons per year. Behind this trend lies a decade of consistently high summer temperatures, which caused significant melting.
In Antarctica, researchers are observing similar losses, increasing from around 48 billion metric tons per year in the 1980s to 202 billion metric tons per year in the 2010s. The losses are greatest in West Antarctica, where relatively warm seawater is melting the floating ice shelves from below. An ice shelf is a large, floating extension of ice connected to the ice sheet.
“You could compare the ice sheet to a tube of toothpaste, where the ice shelf acts much like the cap, holding back the ice behind it. When the ice shelf gets thinner, it’s like unscrewing the cap. Driven by its own weight, the ice can then move more quickly out toward the sea. As much as 84 percent of the total ice loss from Greenland and Antarctica during this period was due to glaciers speeding up and transporting more ice from land out into the sea.”
In recent years, ice losses have been smaller. In East Antarctica, unusually heavy snowfall has temporarily increased the amount of ice, while cooler summers in Greenland have reduced the rate of melting. However, the researchers emphasize that changes over individual years should not be interpreted as a reversal of the long-term trend.
“The time series of measurements, spanning more than 50 years, make it possible to distinguish these variations from the long-term trend and to better understand how the ice sheets are changing over time,” says Nilsson.
Sweden Will Be Affected
The ice loss has contributed just over 3 centimeters to the rise in global sea levels. However, the effect will vary from location to location. In Sweden, post-glacial land uplift is still ongoing, which affects how global sea-level rise is felt along the country's coasts. In southern Sweden, land uplift is minimal, and rising sea levels therefore increase the risk of coastal flooding and erosion. In central and northern Sweden, land uplift is greater and continues to offset a large proportion of the sea-level rise.
Where the ice is disappearing also has an impact on the extent to which sea levels are rising in Sweden. A loss of ice in Antarctica results in a greater rise in sea levels along Sweden’s coasts than an equivalent loss in Greenland. This is partly because the gravitational pull of the ice sheets affects the distribution of seawater across the Earth.
“What is happening in Greenland and Antarctica does not stay there. Three centimeters may not sound like much, but that is just the contribution made by the ice sheets since 1979. As sea levels continue to rise, this will also have consequences for our Swedish coasts, particularly in southern Sweden,” says Nilsson.
Funding: The work forms part of IMBIE (Ice Sheet Mass Balance Inter-comparison Exercise), an international research collaboration supported by the European Space Agency (ESA) and the US space agency NASA. IMBIE compares and combines independent estimates of the mass balance of ice sheets to produce an overall assessment. Among other applications, IMBIE’s compilations of the mass balance of the ice sheets are used as scientific evidence for the IPCC’s climate reports.
Published in journal: Scientific Data
Title: Mass balance of the Greenland and Antarctic ice sheets from the 1970s to 2023
Authors: Inès N. Otosaka, Andrew Shepherd, Charles Amory, Martin Horwath, Erik R. Ivins, Michalea D. King, Sophie Nowicki, Anthony J. Payne, Eric Rignot, Louise Sandberg Sørensen, Nicole-Jeanne Schlegel, Karen M. Simon, Benjamin E. Smith, Tyler C. Sutterley, Michiel R. van den Broeke, Isabella Velicogna, Geruo A, Cécile Agosta, Pavel Ditmar, Thorben Döhne, Marcus E. Engdahl, Xavier Fettweis, Rene Forsberg, Alex S. Gardner, Linda Gilbert, Heiko Goelzer, Noel Gourmelen, Andreas Groh, Nicolaj Hansen, Christopher Harig, Veit Helm, Shfaqat Abbas Khan, Christoph Kittel, Peter L. Langen, Mathias Larsen, Bryant D. Loomis, Malcolm McMillan, Brooke Medley, Daniele Melini, Ruth H. Mottram, Alan Muir, Johan Nilsson, Brice Noël, Mark E. Pattle, Mònica Roca i Aparici, Ingo Sasgen, Himanshu V. Save, Bernd Scheuchl, Ernst J. O. Schrama, Ludwig Schröder, Ki-Weon Seo, Sebastian B. Simonsen, Thomas Slater, Giorgio Spada, Bramha Dutt Vishwakarma, Nander Wever, David N. Wiese, and Bert Wouters
Source/Credit: Uppsala University | Sandra Gunnarsson
Edited by: Scientific Frontline
Reference Number: es091626_01
