Get ready for a chilling tale of the West Antarctic ice sheet's potential fate, a story that could reshape our understanding of the land beneath. Antarctica, with its vast, thick ice sheet, appears as a continuous landmass spanning both hemispheres, but beneath this icy exterior lies a dynamic and controversial narrative.
The West Antarctic ice sheet, shaped like a hitchhiker's thumb, is on the move. Affected by our warming oceans and atmosphere, it's melting at an astonishing rate, and here's where it gets controversial: this melting isn't just about rising sea levels and storm surges, it's about the land itself and the dramatic changes it will undergo.
Researchers, including us, have found evidence in sediment layers on the sea floor that when West Antarctica melted in the past, there was a rapid increase in onshore geological activity. This evidence predicts a future of dramatic shifts and apocalyptic events.
As far back as 30 million years ago, an ice sheet covered much of Antarctica. But during the Pliocene Epoch, the ice sheet on West Antarctica retreated drastically. About 5 million years ago, conditions around Antarctica began to warm, and the ice diminished. This led to a warm climate phase similar to what we're experiencing today.
Glaciers are not static; they flow and move, scraping and carrying debris as they go. When the climate warms, this process accelerates, and glaciers calve into the sea, forming icebergs. These icebergs can carry continental rock material out to sea, dropping it as they melt. This process, combined with the release of pressure on the land as the ice melts, can cause earthquakes and increase volcanic activity, as we're seeing in Iceland today.
In early 2019, we joined a scientific expedition to the Amundsen Sea. Our goal was to recover material from the seabed to understand what happened in West Antarctica during its melting period. We drilled into the ocean floor, recovering sediment cores containing layers deposited between 6 million years ago and the present.
One of our team members, Christine Siddoway, made an unexpected discovery: a sandstone pebble in a disturbed section of the core. Tests showed this pebble came from mountains deep in Antarctica, over 800 miles away. This finding, confirmed by analyzing silt, mud, rock fragments, and microfossils, revealed a deep-water ocean passage across the interior of Antarctica, rather than the thick ice sheet we see today.
The chemical and magnetic properties of the core material provided a detailed timeline of the ice sheet's retreats and advances. Analyses led by Keiji Horikawa matched thin mud layers in the core with bedrock from the continent, showing that icebergs had carried materials long distances. Horikawa discovered multiple mud layers deposited between 4.7 million and 3.3 million years ago, suggesting the ice sheet melted and reformed repeatedly over short spans of time.
Our teammate, Ruthie Halberstadt, combined this chemical evidence with computer models, showing how an archipelago of ice-capped, rugged islands emerged as ocean replaced the thick ice sheets. The biggest changes happened along the coast, with a rapid increase in iceberg production and a dramatic retreat of the ice sheet edge.
The release of pressure on the land as ice melts can cause dramatic shifts, including earthquakes, volcanic activity, and massive rock avalanches and landslides. These events, known as "catastrophic geology," have happened elsewhere on the planet, such as between Utah and British Columbia at the end of the last Northern Hemisphere ice age. Today, we see similar events in coastal Canada and Alaska.
Our analysis of the Amundsen Sea's past and the resulting forecast indicate that the changes in West Antarctica will not be slow or imperceptible. Instead, we can expect geologically rapid shifts that will be felt locally as apocalyptic events, with worldwide effects. When the West Antarctic ice sheet collapses again, catastrophic events will return, and this will happen repeatedly as the ice sheet retreats and advances, opening and closing connections between the world's oceans.
This dynamic future may also bring swift responses in the biosphere, such as algal blooms around icebergs and an influx of marine species into newly opened seaways. Vast tracts of land on West Antarctic islands could turn green with mossy ground cover and coastal vegetation.
The future implications for West Antarctica are profound, and this story is a reminder of the powerful forces at play beneath the ice. It's a tale that highlights the importance of understanding our planet's past to prepare for its future.
