It’s refreshing to see NSIDC director Mark Serreze coming to grips with his role in stirring up Arctic ice scare stories (like the famous “death spiral”) in 2007:
“In hindsight, probably too much was read into 2007, and I would take some blame for that,” Serreze said. “There were so many of us that were astounded by what happened, and maybe we read too much into it.”
With sea ice levels in the Arctic at record lows this month, a new report comparing scientists’ predictions calls for caution in over-interpreting a few weeks worth of data from the North Pole.
The Sea Ice Outlook, which will be released this week, brings together more than a dozen teams’ best guesses at how much sea ice will disappear by the end of the warm season in September. This year began with a surprise. More sea ice appeared than anticipated, nearing its mean level from 1979-2007. But then ice levels plummeted through May and into June. Scientists have never seen the Arctic with less ice at this time of year in the three decades they’ve been able to measure it, and they expect below average ice for the rest of the year.
But looking ahead, the ultimate amount of sea ice melt is hard to determine. Some trends, like the long-term warming of the Arctic and overall decreases in the thickness of sea ice, argue for very low levels of sea ice. But there are countervailing factors, too: The same weather pattern that led to higher-than-normal temperatures in the Arctic this year is also changing the circulation of sea ice, which could keep it in colder water and slow the melting.
“For this date, it’s the lowest we’ve seen in the record, but will that pattern hold up? We don’t know. The sea ice system surprises us,” said Mark Serreze, director of the National Snow and Ice Data Center.
The loss of summer sea ice over decades is one of the firmest predictions of climate models: Given the current patterns of fossil fuel use and the amount of carbon dioxide already in the atmosphere, sea-ice-free summers in the arctic are a virtual certainty by the end of century, and possibly much sooner. As the globe heats up, the poles are disproportionately affected. Warmer temperatures melt ice, revealing the dark sea water that had previously been covered. That changes the albedo, or reflectivity, of the area, allowing it to absorb more heat. That, along with many other feedback loops makes predicting change in the Arctic immensely difficult.