“Curious changes have been taking place, with many animals invading this cold-temperature zone from the south and pushing up through Maine and even into Canada. This new distribution is, of course, related to the widespread change of climate that seems to have set in about the beginning of the century and is now well recognized — a general warming up noticed first in Arctic regions, then in subarctic, and now in the temperate zones of northern states.” — Rachel Carson, The Edge of the Sea, 1955
Ever since the middle of the twentieth century, Arctic warming has been a clear trend to those studying climate. Now, more than a half-century later, we are witnessing what appears to be the rapid demise of Arctic sea ice.
(Image Credit: World Wildlife Fund)
(Image Credit: JAXA)
For 2012, sea ice decline has been inexorable even after a stunning record loss just five years before. With more than two weeks remaining in the melt season, sea ice extent is about 420,000 square kilometers below the record set in 2007 while sea ice area is about 460,000 square kilometers below the record low set last year. If these measurements do not shatter the doubts of skeptics, deniers, and other unrealistic or traumatized persons, then nothing will. Those who cannot recognize these obvious and powerful trends have become inoculated to facts, immune to observations of the world around them, locked in a padded room of their own choosing.
In comparison with past record lows, this year alone is a 10% decline for sea ice extent and a 16% decline for sea ice area. With melt still continuing on an almost daily basis, we can expect these percentages to rise throughout the next couple of weeks. If current rates of decline hold for just the next seven days, we can expect to see loss values for both extent and area exceed 700,000 square kilometers (a 17% decline for extent and a 24% decline for area). If current decline rates hold for another week and a half, the percentage of sea ice area lost will approach the loss for 2007 — 27%.
Given these very high melt numbers, the question for many is — ‘how long can Arctic sea ice survive?’
For an increasing number of scientists and Arctic observers, the number of years remaining is swiftly shrinking. Just this year, a team of British scientists have indicated we could see nearly ice-free seas within a decade. This observation parallels those made by scientists at the Polar Science Center at the University of Washington whose sea ice volume measurements indicated a potential for near ice-free summers within the next five to ten years. Even Andrew Revkin, who has been very reluctant to admit the potential for ice-free summers in the near future, has now said that there’s about a 50% possibility for ice-free conditions within the next twenty years.
Five years ago, before the amazing summer melt of 2007, a person predicting a 50% chance for ice-free summers within twenty years would have faced scorn and derision. Most models indicated that the Arctic Ocean could experience a late summer ice-free condition by the end of this century. A seemingly comfortable, far off time that most didn’t worry about. Now, events are more pressing and far more immediate. Simply put, we are bearing unbelieving witness to the rapid loss of our north polar ice. Many of us just can’t abide with the fact that rates of ice loss indicate a high potential for nearly ice-free summers within the next 5-20 years.
It would take just two more melt seasons like the ones we’ve experienced this year and the one we experienced in 2007, to push sea ice area below 500,000 square kilometers and sea ice extent below 2 million square kilometers. When you consider the fact that these totals are smaller than Greenland, it would be more than fair to call this a nearly ice-free state. When taking into account past summer sea ice extent values at above 10 million square kilometers, this would represent a more than 80% loss since the early 20th century.
Using the same measure, we have currently lost more than 62% of sea ice for end of summer since the early 20th century. Most of this loss has occurred since the mid 1970s. So though loss is high over the course of the past 100 years, it is concentrated toward the end of the period.
To further put the unprecedented nature of this ice-loss period into perspective, it has been found through observations of the age of drift wood frozen in sea ice that this period of melt is the greatest seen in 3000 years. With melt continuing, this 3000 year marker is just a snap-shot of a dynamic and increasingly severe melt event. In the context of greenhouse gas concentration and forcing, we are currently at levels not seen in about 3 million years. So should these CO2 concentrations remain or continue to increase, we are likely to speed past the 3000 year melt mark and on into even less familiar territory.