Arctic Sea Ice Continues Trend of Shrinking Extents

Narration: Katy Mersmann, Claire Parkinson

Transcript:

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On March 17, the Arctic region reached a milestone

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…the second-lowest sea ice maximum extent since satellite measurements began.

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The four lowest maximum Arctic extents on record have been in the last four years,

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according to analysis from NASA and the National Snow and Ice Data Center.

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This year’s maximum extent reached 5.59 million square miles.

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But…what does that really mean?

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How, and why, do we track sea ice?

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We’ve got a good record of extents since the late 1970s.

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So by now, the record of the Arctic ice is clearly

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one of a decreasing ice cover.

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To answer some of my questions, I talked with Dr. Claire Parkinson,

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who has been studying sea ice from space for the past four decades.

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I got a job at NASA’s Goddard Space Flight Center in July of 1978,

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and I’ve been here ever since

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and I’ve had the phenomenal opportunity of getting to start

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when the satellite data were still fairly new and when,

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at Goddard, people were trying to figure out

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how to use the satellite data to reveal information about the Earth.

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After several years when we started getting a longer record,

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then our attention got changed into

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“Well what kinds of trends are we seeing in sea ice?”

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We’ve maintained this record of sea ice and we recognize now

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that it’s very important for climate change,

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because sea ice is one of the variables in the Earth system that has been changing

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the most dramatically, especially in the Arctic.

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But sea ice doesn’t just react to warming global temperatures…

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it can actually accelerate the temperature increases.

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Now the less sea ice coverage feeds back

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into the warming, because if you’ve got less sea ice cover,

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that means less of the sun’s radiation that comes down

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to the surface will get reflected back.

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Sea ice fluctuates with the seasons, growing during the cold,

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dark winters until reaching an annual maximum extent

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in February or March in the Arctic, and then shrinking through the summer

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until reaching a minimum in September.

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In the Arctic case, in late summer, it extends over about 5 million square kilometers.

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In late winter, it extends way further, over about

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15 million square kilometers, which is about one and a half times the area of Canada.

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So studying sea ice

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includes tracking how it changes seasonally. Rather than just looking

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at the annual summer minimum, scientists track how the ice changes throughout the year,

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to get a fuller picture of change.

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Every month of the year has decreases in the Arctic and it doesn’t mean

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every single year has less ice than the year before,

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but it means that, overall, the trend is downward.