The Arctic sea ice cover has melted to its lowest extent since satellite observations of it began more than three decades ago, breaking a previous record low set in 2007.
NASA and scientists at the University of Colorado, Boulder report the Arctic sea ice extent – the amount of ice covering the sea surface – fell to 4.10 million square kilometers in Aug. 26, 2012. And, with more days left in the summer melting cycle, they anticipate even more of a loss before the freeze cycle begins at the end of September.
“By itself it’s just a number, and occasionally records are going to get set. But in the context of what’s happened in the last several years and throughout the satellite record, it’s an indication that the Arctic sea ice cover is fundamentally changing,” said Walt Meier, a scientist at the National Snow and Ice Data Center (NSIDC) at the University of Colorado.
Sea ice in the Arctic goes through a regular yearly cycle of growing and melting. While it doesn’t raise sea level, says Meier, it does have an effect on the climate systems through how much energy gets absorbed from the sun.
Since the Arctic sea ice observational record began in 1979, the trend of ice melt went from slow and steady to more significant as time went on.
Over the last 10 years, according to Meier, this trend quickly began to escalate, with record-breaking years of sea ice melt along the way. The significant drop in the amount of Arctic sea ice, says Meier, “is a kind of an exclamation point on the long term trend.”
NSIDC officials say the previous record low, set back in 2007, happened because of a near-perfect summer weather for melting ice.
“The Arctic used to be dominated by multiyear ice, or ice that stayed around for several years,” Meier said. “Now it’s becoming more of a seasonal ice cover and large areas are now prone to melting out in summer.”
Because of this, he said, what’s occurring now is an overall thinning of the multiyear ice cover, as well as a decrease in the seasonal ice cover.
That thinning continues throughout the entire year because the ice in the wintertime is also thinner than it used to be, reflecting what Meier calls “another big change in the Arctic sea ice system.”
Meier worries about changes to the Arctic, and consequently Earth’s weather systems, should this trend of escalated sea ice melt continue.
The sea ice is very reflective, it’s white and reflects most of the sun’s energy, says Meier. Because there is continuous daylight during the Arctic summer, most of that solar energy is reflected back into space; it doesn’t warm things and helps keep the Arctic cool. Meier calls this process not only the Arctic’s “air conditioner,” but also the entire Earth’s “air conditioner” as well.
“As we lose that sea ice in the summertime,” says Meier, “it gets replaced by the ocean which is very dark relative to the sunlight. It absorbs most of that energy, reflects very little of it, and that energy then heats up the ocean, which heats up the atmosphere and makes the entire Arctic warmer than it normally would be without sea ice.”
This causes greater warming, taking what has been the globe’s air conditioner and kind of “draining out the coolant,” says Meier. As a result, the ability and efficiency of that process to help cool the Earth is reduced as more and more sea ice is lost in the summertime.
There has been a sort of climate balance on Earth between cold in the polar areas and warmth in the equatorial regions. The contrast between the polar cold and the equatorial warmth, according to Meier, sets up weather patterns like the jet-stream, ocean currents, storm tracks and where, when and how much it rains.
Changes in either climate system throw off this balance and disrupt weather patterns. There’s not enough data right now to say for sure what the exact impacts these weather changes will bring, but Meier suspects areas that are dependent on predictable weather patterns – such as agriculture and other things needed to help sustain life on Earth – may be affected. It’s possible, he says, that droughts may become harsher or that more flooding will occur.
Accelerated melting could also impact animals, such as polar bears, who make their homes on the Arctic ice. Meier says some of these polar animals will find new habitats to live in, but others will be forced to either adapt to the changing climate conditions or face extinction.
Walt Meier joins us this weekend on the radio edition of Science World. Check out the right column for scheduled air-times or listen now to the interview below.