Polar ice: sea ice, ice sheets and glaciers

Updated November 2026

The poles hold two kinds of ice: sea ice, frozen seawater a few meters thick, and land ice, the glaciers and ice sheets that can be kilometers deep. Both are shrinking, but only land ice raises sea level when it melts.

Sea ice and land ice

Sea ice forms when the ocean surface freezes. In the Arctic it is smallest in September and largest in March; around Antarctica the seasons are reversed. Because it already floats, melting sea ice does not raise sea level, just as melting ice cubes do not overflow a glass.

Land ice builds up from snow on land. The Antarctic Ice Sheet covers almost 14 million square kilometers and holds about 58 meters of potential sea-level rise; Greenland’s covers about 1.7 million square kilometers and holds about 7.4 meters. Together they store more than 68% of Earth’s fresh water.

Arctic sea ice is shrinking

On September 12, 2026 Arctic sea ice reached its yearly minimum of about 4.60 million square kilometers, tied for tenth lowest in the satellite record with 2008, 2010 and 2025 (NSIDC). The record low is 3.39 million square kilometers, set in September 2012. Since 1979 the minimum has shrunk by about 11.8% per decade, or about 73,200 square kilometers a year: 732,000 square kilometers every ten years. The 20 lowest minimums all came in 2007–2026. Winter ice is shrinking too: the March 2025 maximum was the lowest in the 47-year record.

Antarctic sea ice since 2016

Antarctic sea ice showed no significant overall trend over 1979–2020 (IPCC AR6) and was near record highs in 2013–2015. Since 2016 it has dropped sharply. The record low minimum was 1.79 million square kilometers on February 21, 2023. The September 2025 maximum (17.81 million square kilometers) ranked third lowest, and in early October 2026 daily extents fell to record lows for the date. NSIDC says the years since 2017 are still too few to confirm a new long-term trend.

Ice sheets and sea level

NASA’s GRACE satellites weigh the ice sheets from orbit. Since 2002 Greenland has lost about 264 billion metric tons a year and Antarctica about 135 billion, adding about 0.8 mm and 0.4 mm a year to global sea level: 1.2 mm a year together. In 2025 Greenland lost about 129 billion tons, less than its 2003–2024 average of 219 billion but still a loss (NOAA Arctic Report Card 2025).

From 2012 to 2025 global sea level rose 4.75 mm a year, up from 2.65 mm a year in 1993–2011 (WMO). Comparing the figures, the ice sheets supply roughly a quarter of today’s rise (1.2 ÷ 4.75 ≈ 0.25); mountain glaciers and warming, expanding seawater supply most of the rest.

Pages in this section

For the regions themselves, see Arctic governance and Antarctica and the Treaty.

Check yourself

If all the Arctic sea ice melted, would sea level rise?

Almost not at all. Sea ice already floats. Sea level rises when land ice from glaciers and ice sheets melts or slides into the ocean.

When are the Arctic and Antarctic sea ice minimums?

The Arctic minimum comes in September; the Antarctic minimum comes in February or March.

About how much do the two ice sheets add to sea level each year?

About 0.8 mm from Greenland plus 0.4 mm from Antarctica, or roughly 1.2 mm a year, based on NASA satellite data since 2002.

Sources