A New Theory of Glacier Collapse That Changes Climate Math

Scientists say that silence is the first thing that catches their attention about Antarctica. There is nothing but white stretching toward an unblinking horizon as the wind moves across the ice like a low breath. Thwaites Glacier, also known as the “Doomsday Glacier,” is a Florida-sized block of ice that empties into the Amundsen Sea.

Climate models treated its possible collapse like a set of falling dominoes for years. The glacier may collapse inland in a cascading failure known as marine ice cliff instability if the floating ice shelf at the front is removed, exposing a tall ice cliff. Maps of coastal risk and sea-level projections are products of the calculations that went into that scenario.

According to recent modeling research, collapse might not happen so smoothly or catastrophically.

A mechanism that has grown in significance as the planet warms—meltwater seeping to the base of glaciers and lubricating their slide over bedrock—has been incorporated into the physics of glacier flow by researchers at the University of California, Berkeley and other institutions. The new theory places more emphasis on what occurs beneath the ice, unseen and persistent, rather than cliffs breaking like brittle glass.

While sheer cliff failure might not be enough to cause rapid retreat by 2100, it’s possible that thick, swift-moving glaciers are more susceptible to this lubrication than previously believed. That subtlety is important. It modifies the rate—and possibly the likelihood—of severe sea level rise this century.

One can witness chunks of ice breaking off a glacier’s front with a deep, resonant crack while standing on the deck of an icebreaker in the Amundsen Sea. The scene seems violent and immediate. The true drama, however, might be taking place behind our eyes as meltwater lakes form on the surface, drain through fissures, reach the base, and lessen friction like oil on machinery.

A feedback loop is suggested by the updated models. Glaciers are more susceptible to additional acceleration through basal lubrication when they accelerate for one reason, such as a retreating terminus. More crevasses are opened by faster ice, allowing more water to flow downward and reducing resistance even more. It’s not a line of dominoes. From below, the system is amplifying itself.

It seems as though the climate math has changed from a single, dramatic tipping point to a number of interrelated processes, some of which are gradual and some of which are abrupt.

The worst-case estimates from earlier were real. They were founded on the most up-to-date knowledge at the time. High-resolution simulations, however, now show that ice cliffs must rise above a specific altitude—roughly 135 meters—before they begin to fail consistently. Even then, failure seems to happen more slowly than initially anticipated.

Thwaites is not stable because of that. It implies that the collapse mechanism might not be the same as the story that made headlines.

Another reassuring notion, however, has been called into question by a different line of research from Rutgers University: that iron fertilization from melting Antarctic glaciers might cause algae blooms that absorb carbon dioxide from the atmosphere. Iron in meltwater was significantly lower in field measurements close to the Dotson Ice Shelf than models had predicted. It seems that the ocean’s capacity to naturally fertilize and offset emissions is not as strong as anticipated.

One can’t help but feel both relieved and uneasy as these discoveries mount. I’m relieved that some runaway situations don’t appear to be as likely. Concern that over longer timescales, other feedbacks, such as lubrication-driven acceleration, might prove to be just as destabilizing.

West Antarctica has been steadily losing mass since 2002, according to satellite data. The buttressing effect of floating ice shelves is being weakened by the thinning of these shelves from below due to warm ocean currents slipping beneath them. Inland glaciers accelerate, thin, and retreat if that support is removed.

Whether changes will occur over centuries or if basal lubrication could cause sudden collapses in ten years is still unknown. Although the ice sheet is large, layered, and imperfect, models can replicate flows and friction. Results can be changed by minute changes in the topography of the bedrock.

Forecasts of the climate rely on these nuances. The annual variations in sea level rise of a few centimeters compound over decades, impacting everything from insurance markets to the planning of infrastructure in cities such as Jakarta and Miami. Climate risk appears to be a slow burn for investors. According to the new theory, it might be erratic, quiet for years before abruptly changing when circumstances are right.

Researchers have seen glaciers in Greenland react to meltwater bursts that reach their base in a matter of days. It’s sobering how immediate that is. It implies that glaciers are dynamic systems that respond to temperature and hydrology nearly instantly rather than being inert giants.

There’s a sense that glacier science is shifting from generalizations to more specifics. The storyline has evolved beyond “warming equals collapse.” Ocean currents, bedrock slopes, sediment layers, and waterways are all being impacted by the warming.

Climate math is made more difficult by this intricacy. It also makes it better.

Coastal planners might gain time if the domino theory turns out to be less prevalent. However, the threat still exists if lubrication-driven feedbacks increase; it just takes a different form.

Antarctica does not ultimately fall apart for dramatic effect. Physics affects it. The narrative becomes less dramatic and more complex as scientists work to solve those equations; it is less about a single catastrophic event and more about systems that are pushed, accelerated, and gradually rebalanced under a warming sky.