Not only the size of the sea ice has changed, but so has the character. Arctic ice has become much younger. As NOAA explains, when it comes to ice, age refers to thickness and durability. Young ice it is thinner and is more likely to melt in summer. Older ice – usually four years or more – is ice that survives throughout the year and thickens over time. Per National Snow and Ice Data Center, old ice can grow between 1.8 and 7.6 meters thick.
As you can see in the chart, the older ice in the Arctic is a piece of what it once was. In 1985, 33% of Arctic ice was very old ice; as of March 2020, only 4.4% of sea ice was old.
Conformable NOAA20-30 years ago, the Arctic sea ice was dominated by the old sea ice. Over time, however, the old ice came out of the Arctic through the Fram Strait, where it melted into the relatively warmer Atlantic waters. This was not a problem then, as new batches of old ice were created in Beaufort Gyre, which NOAA describes as a “nursery” for young ice to become thicker and stronger as it moves around. many years. Today, summers in the southern branch of the Beaufort Gyre are often too hot for the ice to survive, the agency said.
To use a phrase from NSIDC, this “Benjamin Button ice” is an element in the dangerous cycle, one in which rising air and ocean temperatures more easily destroy first-year ice and weaken older ice. If this cycle continues and older ice disappears from the Arctic Ocean, the world could see ice-free summers in the Arctic as early as 2030.