The sea ice cover blanketing the Arctic Ocean and nearby seas thickens and expands during the fall and winter each year. It reaches its maximum yearly extent in February or March. This year (2018), on March 17, the Arctic sea ice cover peaked at only 5.59 million square miles (14,478,033.54 km2), the 2nd lowest max on record. It is only about 23,200 square miles (60,000 square kilometers) larger than the record low maximum reached in last year, on March 7, 2017.
This continues a trend of shrinking sea ice, with the four lowest Arctic sea ice maximum extents on record in the last four years. In the video published by the NASA Goddard Channel, Climatologist,
Dr. Parkinson explains: “I got a job at NASA’s Goddard Space Flight Center in July of 1978, and I’ve been here ever since. I’ve had the phenomenal opportunity of getting to start when the satellite data were still fairly new and when, at Goddard, people were trying to figure out how to use the satellite data to reveal information about Earth.”
“After several years when we started getting a longer record, then our attention got changed into ‘well, what kind of trends are we seeing in sea ice?'”
“We’ve maintained this record of sea ice and we recognize now that it’s very important for the climate change because the sea ice is one of these variables in the Earth system that has been changing the most dramatically, especially in the Arctic.”
But the sea ice doesn’t just react to warming global temperatures. It can actually accelerate the temperate increases.
“The less sea ice coverage feeds back into the [global] warming,” says Dr. Parkinson. “Because if you’ve got less sea ice cover, that means less of the Sun’s radiation that comes down to the Earth’s surface will get reflected back.”
Decrease in the Arctic Sea Ice Extent: a continuing trend
Sea ice fluctuates with the seasons: it grows during the cold, dark winters until reaching an annual maximum extent in February or March in the Arctic, and then shrinking through the summer until reaching a minimum in September.
“In the Arctic case, in late summer, it extends over about 5 million km2 (1,930,000 square miles). In late winter, it extends way further, over about 15 million km2 (5.8 million square miles), which is about one and a half times the area of Canada (9.985 million km2).”
So, studying sea ice includes how it changes seasonally. Rather than just looking at the annual summer minimum, scientists track how the ice changes throughout the year, to get a fuller picture of change.
“Every month of the year has decreased ice levels in the Arctic and it doesn’t mean every single year has less ice than the year before, but it means that, overall, the trend is downward.”
The Arctic has gone through repeated warm episodes this winter, with temperatures climbing more than 40 °F (22 °C) above average in some regions. The North Pole even experienced temperatures above the freezing point for a few days in February.
The stunning video below, taken from a bird’s eye view by photographer Peter Cox shows icebergs and ice sheets rapidly melting in the Arctic. United Nations Environment Program said that global warming has been responsible for the melting sea ice around the North Pole.
- “Arctic Wintertime Sea Ice Extent Is Among Lowest On Record” on NASA Goddard web site
- Arctic Ocean on wikipedia
- Dr. Claire L Parkinson biography on NASA.gov
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