What is the record minimum Arctic sea ice extent when did it occur?
The record-lowest minimum extent occurred in 2012 at 3.39 millions square kilometers (1.31 million square miles). This time series ends on September 24, 2020. Researchers who study climate and sea ice expect that at some point the Arctic Ocean will lose its ice cover in late summer.
Why has no new record minimum Arctic sea ice extent occurred since September 2012?
No new records have been set since then, however, owing to an abrupt atmospheric shift during each August/early-September that brought low sea-level pressure, cloudiness, and unfavorable wind conditions for ice reduction.
What happened to Arctic sea ice in 2012?
Between the seasonal maximum extent that occurred on March 20, 2012 and the September 16 minimum, the Arctic Ocean lost a total of 11.83 million square kilometers (4.57 million square miles) of ice; this is by far the largest seasonal loss of sea ice in the satellite record.
What was the average September sea ice extent in 2012?
Overview of conditions. On September 16, 2012 sea ice extent dropped to 3.41 million square kilometers (1.32 million square miles). This appears to have been the lowest extent of the year. In response to the setting sun and falling temperatures, ice extent will now climb through autumn and winter.
How large of an area in the Arctic did sea ice cover in 2012?
1.58 million square miles
Details. On August 26, 2012, Arctic sea ice extent shrank to 1.58 million square miles (4.1 million square kilometers), an area about half the size of the Lower 48 United States. That ice was melting was not news; after all, the Arctic ice pack undergoes an annual cycle of winter expansion and summer melting.
What is the current extent of Arctic sea ice?
Overview of conditions Average Arctic sea ice extent for June 2022 was 10.86 million square kilometers (4.19 million square miles), ranking tenth lowest in the satellite record (Figure 1). The 2022 June extent was 900,000 square kilometers (347,000 square miles) below the 1981 to 2010 average.
What is perennial ice cover?
Perennial ice is, in theory, resistant to melting in summer. It’s thicker, and generally has a deeper cover of protective snow on top. By positioning robust ice in an area where ice typically melts, scientists may record more ice coverage come the September minimum.
Why is sea ice melting harmful?
Melting glaciers add to rising sea levels, which in turn increases coastal erosion and elevates storm surge as warming air and ocean temperatures create more frequent and intense coastal storms like hurricanes and typhoons.
How is sea ice extent calculated?
To estimate ice area, scientists calculate the percentage of sea ice in each pixel, multiply by the pixel area, and total the amounts. To estimate ice extent, scientists set a threshold percentage, and count every pixel meeting or exceeding that threshold as “ice-covered.” The common threshold is 15 percent.
Is Arctic sea ice increasing or decreasing?
Sea ice in the Arctic has decreased dramatically since the late 1970s, particularly in summer and autumn. Since the satellite record began in 1978, the yearly minimum Arctic sea ice extent (which occurs in September) has decreased by about 40% [Figure 5].
How has the maximum sea ice extent in the Arctic changed since 1979?
Since 1979, scientists have observed a decrease in the extent of Arctic sea ice in all months of the year. The September minimum extent is 36.5 per cent smaller in the period 2010–2019 than it was in the 1980s.
When was the last time the Arctic ocean was ice free?
In July of 2020, the area covered by sea ice in the Arctic Ocean reached a new low for the month. With record warming caused by human activity, the Northern Sea Route became ice-free earlier than previously recorded. At the end of July, Canada’s last intact ice-shelf collapsed.
When was the last time the Arctic was ice free?
Summary: Recent mapping of a number of raised beach ridges on the north coast of Greenland suggests that the ice cover in the Arctic Ocean was greatly reduced some 6000-7000 years ago. The Arctic Ocean may have been periodically ice free.
What is the extent of Arctic sea ice?
Overview of conditions Average Arctic sea ice extent for May 2022 was 12.88 million square kilometers (4.97 million square miles) (Figure 1). This was 410,000 square kilometers (158,000 square miles) below the 1981 to 2010 average, yet it was the highest May extent since 2013.
How is the Arctic sea ice extent defined?
Figure 1 shows Arctic sea ice extent from 1979, when routine monitoring by satellites started, to 2020. Sea ice extent is defined as the area of ocean where at least 15 percent of the surface is frozen. This threshold was chosen because scientists have found that it gives the best approximation of the edge of the ice.
What is happening to the minimum Arctic sea ice?
Arctic sea ice reaches its minimum each September. September Arctic sea ice is now declining at a rate of 13% per decade, relative to the 1981 to 2010 average. This graph shows the annual Arctic sea ice minimum each September since 1979, derived from satellite observations.
Why is Arctic sea ice extent important?
The area covered by Arctic sea ice is an important indicator of global climate change because as global temperatures rise, the rate at which warmer air and warmer water temperatures reduce the amount of existing sea ice can be measured.