by Kimberly Hatfield
At its simplest, sea ice is frozen ocean water, a force of nature. It covers nearly 10 million square miles of Earth’s polar ends, and plays a critical role in regulating ocean currents and climate balance. Arctic sea ice is the pillar for life above and below the water, and is an important barometer of climate change.
FACT: Arctic winter sea ice has declined by 3-4% per decade since the 1980s. Scientists at the National Snow and Ice Data Center (NSIDC) study Earth’s frozen regions using satellites and data from field expeditions. Shipping and weather records, some dating back centuries, also provide historical trends. Satellite data shows that Arctic sea ice extent, or cover, is in decline. Sea ice reaches a maximum level in March and a minimum summer level in September, and NSIDC studies show summer sea ice has declined a whopping 30% in the past 30 years.FACT: In 2012, Arctic sea ice reached record low levels. Julienne Stroeve, PhD, Senior Research Scientist at NSIDC traveled to the Arctic Ocean to study sea ice during 2012. She found the view from ground level much different from what she had expected from her research. The ice was much more broken up and there was more open water than our passive microwave algorithms indicate. So that means that even though the extent may have been high in the region I was observing, in reality it was quite a bit lower, so sometimes the satellite observations may be conservative, she says. In September 2012, Arctic sea ice reached a record low of 3.41 million square kilometers; it was 49% less than average from 1979-2000, according to the NSIDC.
FACT: 80% of sunlight striking snow-covered sea ice is reflected back into space. The Polar regions play a critical role in regulating global temperatures. Earth’s oceans and atmosphere systematically circulate to the colder Poles to help balance temperature. Sea ice is an excellent insulator for the warmer ocean below, and its brilliant white surface is a very effective screen from the sun’s powerful rays. Managing temperatures and protecting from the sun, sea ice is the earth’s perfect middle layer.
FACT: The Arctic was warmer during the 20th century than any time since the 1600s Global warming has affected the Arctic more than any other region on earth, say many researchers, and loss of sea ice may be adding fuel to the fire. As sea ice decreases, darker ocean water is exposed to the sun’s powerful rays, which may in turn spur an unwelcome cycle of warmer water ultimately melting more sea ice. If this continues, the aforementioned vital middle layer could be worn thin, and there have been predictions that we will see an ice-free summer in our lifetimes.
FACT: Sea ice is alive! During the 6-months of winter, temperatures average around -30F. The saline ocean surface freezes, releasing salt and storing key nutrients within its layers. Ice crystals measuring 1/8 inch can eventually form ridges 20 feet thick, and the underside of that ice is alive with algae and other organisms adapted to extreme conditions, thus forming important building blocks of the region’s food chain.
FACT: Sea ice actually ages. In the summer, temperatures rise to about 32F and the ice releases fresh water and vital nutrients as sunlight reaches the ocean, stimulating new life and a fresh supply of food. Historically, some ice persists throughout the summer, becoming older, stronger “multiyear ice.” Polar bears rely on this ice for hunting and cover.
FACT: Sea ice provides habitat for the region’s sea and land animals. The Arctic is home to many of the world’s most rare and spectacular wildlife, including the iconic polar bear. Marine mammals and animals rest, birth and nurse their young on the ice’s surface. Seal pups need at least 12 days on sea ice to nurse, and snow-white Canadian Ivory gulls closely tie breeding, feeding and migration with sea ice. These gulls have experienced an 80% drop in populations in Canada since the 1980s, reports SeaWeb. Data on polar bear populations, estimated to be between 20,000 and 25,000 (2008), is being closely watched. The area of Canada’s Western Hudson Bay, for example, experienced a 22% population decline that was directly tied to longer ice-free seasons on Hudson Bay says Polar Bear International.
There are many ways your family can learn more, and make a difference. Check out NASA s kid-friendly site on climate change. Take the “ocean pledge” at Seaweb.org. Be good stewards through the plants you grow, the purchases you make, the organizations you support, and the waste you reduce and recycle. Unplug, change a bulb, have a meatless Monday, and carpool. Your small connections make a difference.
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Kimberly Hatfield is a freelance writer on the East Coast focusing on health, nature and business. Follow her on Twitter at @fieldnotes2014.