Antarctica is losing ice, warming from below, and watching its ecosystems unravel. The continent sheds roughly 135 billion tons of ice per year, enough to raise global sea levels by 0.4 millimeters annually. That number, tracked by NASA’s GRACE satellites from 2002 to 2025, represents the net balance after accounting for snowfall gains in the east and massive losses in the west. The effects ripple outward from the ice itself to the ocean, the atmosphere, and every species that depends on the frozen landscape to survive.
Where the Ice Is Disappearing
Antarctica’s ice loss is not evenly distributed. The West Antarctic Ice Sheet is the primary source of trouble, losing far more ice than the modest gains from increased snowfall in parts of East Antarctica. Two glaciers in particular drive much of the concern: Thwaites and Pine Island.
Thwaites Glacier, often called the “doomsday glacier,” is larger than Florida and holds enough frozen water to raise global sea levels by 0.6 meters on its own. It already accounts for 4% of global sea level rise. Warm ocean tides push beneath the glacier and eat away at its underside, and the point where the ice meets the bedrock (the grounding line) is retreating at roughly 500 meters per year. Pine Island Glacier tells a similar story: between 1992 and 2011, its grounding line pulled back 20 kilometers on average, reaching 40 kilometers of retreat in the central section. During those same two decades, the ice thinned by more than 200 meters.
If every bit of Antarctic ice melted, global sea levels would rise 58 meters. That’s not a realistic near-term scenario, but it illustrates the sheer scale of what’s stored on the continent. Under high-emission projections, Antarctica alone could contribute up to 15 centimeters of sea level rise by 2100. Under low-emission scenarios, some models suggest the ice sheet could stabilize or even grow slightly, though current observations of ongoing net loss make that optimistic.
Warming From the Ocean Up
The atmosphere above Antarctica has warmed at about 0.12°C per decade since 1957, adding up to roughly 0.5°C total. The Antarctic Peninsula, which extends northward into warmer waters, has warmed far more dramatically than the continental interior. But the bigger story is happening underwater.
The Southern Ocean absorbs a staggering share of the planet’s excess heat. From 1970 to 2017, it stored 35 to 43% of the heat gained by the world’s upper oceans. In recent years that share has climbed to somewhere between 45 and 62%. Deep below the surface, warm water known as Circumpolar Deep Water is creeping onto the continental shelf and melting ice shelves from underneath. This “basal melting” is the primary driver of ice shelf thinning in the Bellingshausen and Amundsen seas, where melt rates have increased by an average of 30% across individual shelves, with some experiencing increases up to 60%.
This process matters because ice shelves act as brakes. They float on the ocean surface at the edges of the continent and hold back the glaciers behind them. As they thin and weaken, glaciers flow faster toward the sea, accelerating ice loss.
The Sea Ice Feedback Loop
Sea ice plays two critical roles in regulating Antarctica’s climate. First, its bright white surface reflects up to 80% of incoming sunlight back into space. Open ocean water, by contrast, reflects only about 6%. When sea ice disappears, the dark water absorbs far more solar energy, which warms the ocean further, which melts more ice. This self-reinforcing cycle is called the ice-albedo feedback.
Second, sea ice acts as an insulating blanket, reducing heat transfer between the ocean and the atmosphere by roughly a hundredfold. When it vanishes, the ocean dumps stored heat into the air, raising local temperatures and making future melt events more likely. The combination of these two effects means that losing sea ice doesn’t just reflect current warming. It amplifies it.
Emperor Penguins and Breeding Collapse
In 2022, Antarctic sea ice hit record lows, and the consequences for wildlife were immediate. In the Bellingshausen Sea region, some areas lost 100% of their sea ice during the critical breeding months. Of five emperor penguin breeding colonies studied in the region, four experienced total breeding failure. Every chick died before growing waterproof feathers, likely drowning when the ice broke apart beneath them.
This was the first recorded case of widespread emperor penguin breeding failure clearly linked to large-scale sea ice loss across multiple sites in a single season. Individual colonies have failed before, and some marginal colonies lose their ice so regularly that scientists call the pattern “blinking.” But simultaneous collapse across a region was unprecedented. One colony at Halley Bay in the Weddell Sea had already been forced to relocate 85 kilometers south after local sea ice disappeared starting in 2016. Population modeling based on current warming trends projects that over 90% of emperor penguin colonies will be functionally extinct by the end of this century.
Krill Decline and the Food Web
Antarctic krill, small shrimp-like creatures that form the base of the Southern Ocean food web, have experienced an estimated 38 to 81% reduction in biomass over the past few decades. Krill density has dropped by as much as 80% since the mid-1970s, closely tracking the decline in winter sea ice. Krill depend on the underside of sea ice during their early life stages, feeding on algae that grows there. Less ice means fewer krill.
The effects cascade upward. Adélie and chinstrap penguin populations have declined as krill became scarcer, even though krill still dominates their diet. The penguins haven’t switched to other food sources; there simply isn’t enough krill to go around, especially as recovering whale and fur seal populations compete for the same supply. If warming continues to reduce winter sea ice in the western Antarctic Peninsula and Scotia Sea, krill recruitment will remain sporadic and penguin numbers will likely keep falling.
What the Next Decades Look Like
The trajectory depends heavily on emissions. Under high-emission scenarios, Antarctica could contribute up to 15 centimeters to sea level rise by 2100, on top of contributions from Greenland and thermal expansion of warming oceans. The glaciers already in retreat, particularly Thwaites and Pine Island, may reach tipping points where their collapse becomes self-sustaining regardless of future temperature changes. Under low-emission scenarios, some stabilization is possible, but even at 1.5°C of global warming the continent will continue losing ice based on current observations at just 1.1°C.
The Southern Ocean will keep absorbing heat, ice shelves will keep thinning from below, and the feedback loops between ice loss, albedo, and ocean warming will continue reinforcing each other. For the species that depend on sea ice, particularly emperor penguins and krill, the window for preserving viable populations narrows with every decade of warming.