BOULDER, COLORADA (NYTIMES) - A "crazy year" in the Arctic has resulted in the second-lowest extent of sea ice in the region, scientists said Monday (Sept 21).

Researchers with the National Snow and Ice Data Centre said the minimum was most likely reached on Sept 15, with 3.7 million sq km of ocean covered in ice.

Since then, with temperatures falling and new ice forming, coverage has been increasing.

Since satellite measurements of sea ice began four decades ago, only 2012 has had a lower minimum, when 3.4 million sq km were measured.

The 2020 minimum was nearly 2.6 million sq km less than the average annual minimum between 1981 and 2010.

This year also continues an alarming streak: The 14 lowest ice years have occurred in the past 14 years. Many scientists expect that the Arctic could be devoid of ice in summers well before mid-century.

"It's been a crazy year up north, with sea ice at a near-record low, 100-degree heat waves in Siberia, and massive forest fires," Mark Serreze, director of the National Snow and Ice Data Centre, said in a statement.

"We are headed towards a seasonally ice-free Arctic Ocean, and this year is another nail in the coffin."

Arctic sea ice grows to its maximum extent during fall and winter and then melts during spring and summer.

The maximum this year, 15.2 million sq km, was reached in early March.

The researchers noted that as it is every year, their announcement of a minimum was preliminary: A brief warm spell or shifting winds could bring more melting. That has happened twice in this century.

Temperatures soared across much of the Arctic this summer. In late June, Siberia was engulfed by a zone of stagnant air that kept heating up.

This led to record temperatures: Verkhoyansk, Russia, 643km farther north than Anchorage, Alaska, reached 37 deg C one day.

Sea ice has been shrinking by more than 13 per cent per decade, relative to the 1981-2010 average, as global warming affects the Arctic more than any other part of the world.

The region is warming more than twice as fast as any other.

Sea ice loss plays a role in this rapid warming. Ice reflects most of the sunlight that strikes it.

But when it melts, more ocean is exposed. The ocean surface is darker and absorbs more of the sun's rays, re-emitting the energy as heat.

That leads to more warming and more ice loss, with the process continuing in what scientists call a feedback loop.