How much Antarctic ice has melted recently?

A continent‑wide record shows faster grounding‑line retreat

A three‑decade satellite record has produced the first continent‑wide map of grounding‑line migration — the places where ice sheets detach from bedrock and begin to float. Analyses of those radar data indicate Antarctica has lost a very large area of grounded ice over the past 30 years: scientists summarize the net loss as roughly ten times the size of Greater Los Angeles, with an average grounding‑line retreat on the order of several hundred square kilometres per year (reported values center near 442 km² per year for the period analyzed).

Why grounding lines matter

Grounding lines mark the boundary that holds back inland ice. When they retreat, grounded ice is exposed to faster flow and melting, which can accelerate discharge into the ocean. That amplifies sea‑level rise beyond what would occur from surface melting alone.

Consequences and takeaways

• The new, high‑resolution record shows sustained, widespread retreat rather than isolated, short‑term shifts.
• Many coastal hazard and risk assessments have assumed lower present‑day sea levels; updating those baselines is likely to raise near‑term exposure for people and infrastructure.
• The results underscore the need to improve ice‑sheet models and to integrate the new grounding‑line data into projections used for coastal planning.

Uncertainties remain about how fast the trend will continue: ice‑sheet dynamics are complex and influenced by ocean warming, bedrock geometry and future climate forcing. But the new map removes a major blind spot in observations and strengthens the evidence that Antarctic changes are already contributing to global sea‑level rise.