Editorial: The grim story of melting Arctic ice
This image made available by NASA shows the amount of summer sea ice in the Arctic on Sunday, Sept. 16, 2012, at center in white, and the 1979 to 2000 average extent for the day shown, with the yellow line. Scientists say sea ice in the Arctic shrank to an all-time low of 1.32 million square miles on Sunday, Sept. 16, 2012, smashing old records for the critical climate indicator. That's 18 percent smaller than the previous record set in 2007. Records go back to 1979 based on satellite tracking. (AP Photo/U.S. National Snow and Ice Data Center) Purchase photo reprints »
Advances in climate science will enable us to understand how a warming planet is a changing planet. Consider two recent studies that received deserved coverage. The news isn’t at all encouraging.
Last week, researchers with the U.S. National Snow and Ice Data Center reported that the amount of Arctic sea ice visible from space fell to its lowest recorded level, based on satellite images since 1979. For years, scientists have believed that disappearing Arctic ice would provide a first measure of global warming. With declines charted this summer, they are warning that Arctic ice is disappearing faster than scientific models predicted.
A researcher with the data center, Julienne Stroeve, said the new evidence suggests that the Arctic could be ice-free before 2050, the date earlier forecast for that development. The center says the record for the least amount of Arctic ice was broken Aug. 26, when it fell below levels charted in 2007. Gone was an area of ice larger than Texas. August is near the end of summer at the top of the planet. The amount of ice rises and falls yearly, with the changing seasons.
But this year, something is happening up north at summer’s end that has scientists talking. Even with less direct sun, the ice has been disappearing. That suggests, according to Walt Meier of the data center, that the ice cover that remained through the summer is thinner and more fragile than the ice that remains in solid form from one year to another. In other words, even a weaker sun up north in August and September has been able to melt it.
Because of planetary warming, scientists reason, ice just isn’t growing back at the poles during winter seasons as it once did.
A satellite study found that the extent of ice present a week ago in the Arctic was 1.32 million square miles — the smallest frozen area in the ocean since record-keeping began 33 years ago.
Not surprisingly, the loss of Arctic ice has northern hemisphere governments racing to gain advantage over new transportation routes and fishing stocks. That is understandable; we can only wish governments, particularly our own, responded as energetically to the crisis of global warming.
Less ice in the Arctic, scientists note, means the loss of the cooling effect that helps moderate temperatures to the south, and produces more moisture in the climate. The decrease in ice in the Arctic is believed to influence the shape and position of the jet streams, those rivers of strong winds in the upper levels of the atmosphere. A climate scientist with the National Resources Defense Council says that melting Arctic ice will likely result in tropical air flowing further to the north and for colder Arctic air to reach more areas lower on the globe. Both changes are expected to accelerate extreme weather. Expect longer cold and hot spells alike.
Down at the other end of the planet, offshore Antarctic ice is growing, as that region comes out of its winter season. But don’t be cheered by that fact. As science journalist Michael D. Lemonick noted in a post Saturday on the ClimateCentral.org website, Antarctic sea ice has increased by about 1 percent per decade over the past three decades. The ice loss in the Arctic, by contrast, was 15.5 percent per decade. And while Antarctic sea ice is growing slightly, Lemonick notes that the ice positioned atop the land mass at the South Pole is shrinking “at an accelerating rate, with worrisome implications for global sea level rise.”
He says scientists have long predicted that temperatures would rise in the Arctic faster than at the South Pole, where ice sits on land surrounded by oceans (the Arctic, contrast, is an ocean ringed by land masses). When — not if, but when — the planet’s southernmost ice melts, that will fuel rising sea levels everywhere. Earlier this summer, a study by U.S. Geological Survey scientists found that sea levels on the East Coast of the U.S. are rising faster than elsewhere. A project led by Asbury Sallenger Jr. called a 600-mile zone from North Carolina to north of Boston a “hot spot.” It found that since 1990, sea levels have been rising three to four times faster than the global average of 2 inches a year. The levels are up 4.8 inches a year in Norfolk, Va., for instance.
By the year 2100, sea levels around the world could climb by 3.3 feet, according to computer models. Sallenger’s study suggests that levels on the East Coast could exceed that by 8 to 11 inches.
The consequences will be felt most dramatically during Atlantic storms. And the nature and intensity of those future storms, scientists say, will be influenced by changes in bigger climate patterns, including shifts in the jet streams. Scientists are bringing us tomorrow’s story on climate change today. We must listen and learn from what they have to teach us.