7 of Top 10 Polar Ice Sheet Melting Years Happened in Last Decade

Areas in red highlighting changes to the thickness of Greenland's ice sheets between 1992-2020. Image: Northumbria University at Newcastle

For those wanting a more visual idea of what this means, this is about the same amount of ice as would be contained in an ice cube roughly 12.5 miles (20 kilometers) on each side.

That melting has also contributed to a net 0.8 inches (21 millimeters) of global sea level rise during that almost thirty-year period.

The research also showed that glacier and other melting in Greenland and Antarctica were the two largest contributors to that overall melt loss and sea level rise since 1992. Almost two-thirds of that melting comes from Greenland, which by itself has contributed to 0.53” (13.5 mm) of total sea level rise. Most of the other net melting, almost one-third of the total, comes from Antarctica, where melting has caused seas to rise by 0.29” (7.4 millimeters).

Other analysis showed polar ice melting, while significant by itself, is only about a fourth of total sea level rise due to ice melt throughout the world, almost all of which eventually finds its way to the oceans. That means the total sea level rise from all melting works out to about 3.3 inches or 84 millimeters.

While that may seem low, it is disproportionately distributed nearer to the equator and is more than enough to induce flooding at far higher rates than ever before on all coastal areas.

A comparison of the accelerating melting rates in the Arctic and Antarctic regions. Image: University of Leeds, etc., and the Journal Earth System Science Data, CC

The rate of polar ice melt is also accelerating, at a rate which the Intergovernmental Panel on Climate Change (IPCC) projects will on its own produce net sea level rise of between roughly 6 inches to 11 inches on average by the end of the century. Since the factor of three multiplier to figure total sea level rise will still apply due to all other melting, that means total sea level rise will, by these calculations, amount to a net rise of 24 to 44 inches worldwide by 2100. That works out to a possible average rise of about 3.5 feet.

That will also disproportionately be distributed closer to the equator because of the earth’s rotation, with ocean levels rising by as much as two or three times those values. At the high end of the estimates, that would mean total sea level rise close to the equator could be as high as 11 feet (3.4 meters) at the extreme.

With roughly 10% of the world’s population living close to sea level, that could mean climate displacement of at least 1.1 billion people less than 80 years from now. It will also mean the almost certain submerging of cities such as Miami, U.S.; Shanghai, China; Manila, Philippines; Bangkok, Thailand; and Kolkata, India, at the same time, not to mention the wiping out of entire nations such as the Pacific Island country of Vanuatu and most of Bangladesh.

The data would mean the extreme weather events the world is experiencing now, in terms of hurricanes and super cyclones, would bring with them storm surges as much as 30 feet high on a regular basis.

This is all an enormous jump from the polar ice melt rates going back to just before this data was taken. As of the early 1990s, polar ice melt was virtually flat, with some melting seasonally only to have most of it recovered and reconverted into ice later in the same year. That is why ice sheet melting at the time contributed to only 5.6% of all sea level rise at that time. Since that time, however, polar ice melting rates have accelerated by a factor of five and will likely continue to accelerate even more.

The study, published by a collective of researchers with Northumbria University in Newcastle, U.K., acting as a lead hub for the investigation, is based on extensive satellite data provided by the Ice Sheet Mass Balance Inter-Comparison Exercise, or IMBIE for short. IMBIE was founded in 2011 as a long-term collaborative project between the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA) of the United States. The goal of the collaboration was to provide more confidence in metrics regarding precisely how fast the global cryosphere is melting, and how it contributes to global sea level rises.

The cryosphere includes ice melt from all regions, with the Arctic (extending down through Siberia as an important subset of that area), Greenland, Antarctica, and the Himalayan Mountain Range in Asia being some of the most important contributors.

This current third formal assessment of the state of polar melting on behalf of IMBIE involved data analyzed by 68 polar science specialists representing 41 international organizations. The information used to calculate the net impact of global melting came from 17 separate satellite missions carried out jointly by the ESA-NASA team.

In summarizing their results, besides calling attention to the total sea level rise contributed by polar melting since 1992, the researchers also noted that polar ice melting is accelerating at alarming rates.

They reported that the worst year of polar ice melting to date was in 2019, when those two regions lost 612 billion tons of ice. A then-unusual Arctic heatwave caused Greenland to shed a record 444 billion tons of ice just in that year alone. The same year glaciers in West Antarctica lost 168 billion tons of ice on its own; that was its sixth-highest melt rate in history.

This data builds on recent studies which have shown the Arctic has this century been warming at rates 4X what the rest of the planet has been experiencing.

As the Arctic melting continues to grow more extreme, secondary effects such as permafrost warming will release new vast stores of carbon dioxide and methane. That will build more heat trapping capacity into the atmosphere and cause global temperatures to rise even faster.

Antarctica also continues to set melting records, with recent sea ice levels at their lowest levels in the entire 44 years since measurements started for that.

As Antarctica’s glacial sheets melt further, one of the newer threats discovered is about how an important ocean current in the Southern Oceans could slow or stop completely. When that happens, ecosystems will fragment, marine species will perish because not all can migrate to adapt, and wind currents will be widely disrupted in the Southern Hemisphere.

The paper describing this third assessment of the IMBIE polar melting dataset, “Mass balance of the Greenland and Antarctic ice sheets from 1992 to 2020,” by Inés N. Otosaka, et. al., was published on April 20, 2023, in the journal Earth System Science Data.