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Effects & Impacts: Antarctica melting

Larsen C ice shelf fracture image: John Sontag NASA

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Antarctica melting

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Summary

  • Antarctica is almost twice the size of Australia and contains 90% of the world’s freshwater that, if it all melted, would add ~60-70m to sea levels.
  • 125,000 years ago when temperatures and CO2 levels were similar to that of today, sea levels were ~6-10 metres higher than today.
  • Over the past 50 years, the west coast of the Antarctic Peninsula (Figs. 2 & 3) has been one of the fastest warming parts of the planet, with air temperatures five times the average rate of global warming due to polar amplification.
  • The East Antarctic Ice Sheet (EAIS)(Figs. 2 & 3) is not as stable as previously thought and is contributing to rising sea levels. Temperatures there reached 38.5°C above normal in 2022, a new world record for the largest temperature excess above normal ever measured at an established weather station.
  • The Western Antarctic Ice Sheet (WAIS) covers islands and land below sea level (Figs. 2-4), which makes it particularly vulnerable to collapse. The Thwaites Glacier is currently of greatest concern. Increasingly warmer ocean water is melting it from below, undercutting it so that it’s collapsing. Nicknamed the ‘Doomsday Glacier’, it acts like a plug, holding back the WAIS ice sheet.

The ‘Doomsday Glacier’ is poised to lose its ice shelf this year. – Live Science May 2026

Home > Climate wiki > Effects > Antarctica melting

Summary

  • Antarctica is almost twice the size of Australia and contains 90% of the world’s freshwater that, if it all melted, would add ~60-70m to sea levels.
  • 125,000 years ago when temperatures and CO2 levels were similar to that of today, sea levels were ~6-10 metres higher than today.
  • Over the past 50 years, the west coast of the Antarctic Peninsula (Figs. 2 & 3) has been one of the fastest warming parts of the planet, with air temperatures five times the average rate of global warming due to polar amplification.
  • The East Antarctic Ice Sheet (EAIS)(Figs. 2 & 3) is not as stable as previously thought and is contributing to rising sea levels. Temperatures there reached 38.5°C above normal in 2022, a new world record for the largest temperature excess above normal ever measured at an established weather station.
  • The Western Antarctic Ice Sheet (WAIS) covers islands and land below sea level (Figs. 2-4), which makes it particularly vulnerable to collapse. The Thwaites Glacier is currently of greatest concern. Increasingly warmer ocean water is melting it from below, undercutting it so that it’s collapsing. Nicknamed the ‘Doomsday Glacier’, it acts like a plug, holding back the WAIS ice sheet.

The ‘Doomsday Glacier’ is poised to lose its ice shelf this year. – Live Science May 2026

  • Ice sheet: continental glaciers that have joined together to cover the surrounding land in an area greater than 50,000 km². There are only three in the world: Greenland, and two in Antarctica: the WAIS and the EAIS (Processes: Fig. 1). The existence of these ice sheets are why we are still in an ice age.
     
    • Marine ice sheet: an ice sheet whose base is on ground below sea level. This makes it particularly vulnerable to undercutting by warming waters (Fig. 1). The WAIS is largely a marine ice sheet (Figs. 2 & 3).
    • Outlet glacier: drains inland glaciers/ice sheets through gaps in the surrounding topography. If an outlet glacier reaches the coast (some terminate inland) it can become an:
    • Ice shelf: a tidewater (coastal) glacier or ice sheet that flows down to a coastline and onto the ocean surface, where it floats. Pine Island and Thwaites Glaciers are outlet glaciers with ice shelves; the Thwaites ice shelf is now breaking up (May 2026).
    • Grounding line: the point where the bottom or ‘basal’ (bottom) side of a glacier leaves land and extends out over the ocean (Fig. 1).
      • If the grounding line is below sea level, the glacier is prone to undercutting by increasingly warmer ocean waters (Fig. 1) 
      • If land behind the grounding line slopes down inland instead of upwards, warm water can flow further underneath inland, destabilising the glacier even faster (Fig. 1). Thwaites Glacier, now considered the most unstable is grounded below sea level, and much of the the land behind the grounding line slopes down.
Fig. 1: Antarctica showing the Larsen and Wilkins Ice Shelves, Pine Island Glacier, and Thwaites Glacier — an ice shelf roughly the size of UK (176 x103 km2). The front of the glacier—its terminus—is nearly 120 km wide and >1000m below sea level.
Fig. 2: Antarctica showing the Larsen and Wilkins Ice Shelves, Pine Island Glacier, and Thwaites Glacier — an ice shelf roughly the size of UK (176 x103 km2). The front of the glacier—its terminus—is nearly 120km wide and >1000m below sea level.
Fig. 2: Antarctica without ice (not accounting for any isostatic rebound). The West Antarctic Ice Sheet (WAIS) sits largely on islands and underwater trenches. This makes it particularly vulnerable to undercutting and collapse.
Fig. 3: Antarctica without ice (not accounting for any isostatic rebound). The West Antarctic Ice Sheet (WAIS) sits largely on islands and underwater trenches. This makes it particularly vulnerable to undercutting and collapse.
How Antarctica looked in Earth’s past when temperatures were last between 1°C and 2°C (~125,000 years ago). Image: Lau et al; 2023
Fig. 4: How Antarctica looked the last time  temperatures were between 1°C – 2°C warmer (~125,000 years ago). Image: Lau et al; 2023.

A first threshold, potentially as low as 1–2 °C above pre-industrial levels, triggers the long-term collapse of ~40% of marine ice volume in West Antarctica. Marine-based sectors in East Antarctica, representing ~5 m of potential sea-level rise, are at risk of losing stability at 2–5 °C. – Winkelmann et al 2026

2024 was warmest year on Earth since direct observations began… 1.62°C above our 1850-1900 average, making it the second year above 1.5°C. Berkeley Earth, 2025
Video 7: Prof.Tim Naish from Wellington University explains what Antarctica may be melting faster than anyone realizes, and the implications for humanity are potentially disastrous.

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