Spying on Sea Ice | Popular Science

Arctic researchers rely on a fleet of unmanned aircraft
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After the record minimums of 2007 and 2008, researchers will be watching the 2009 sea ice outlook closely. "We're heading towards an Arctic that won't have any sea ice in 20-30 years -- the most recent research indicates that the last time that happened was at least 5,500 years ago," said [Walt] Meier. "To get back to the sea ice levels we saw in the 1980s would take several very cold winters in a row."

1. If a temporarily ice-free Arctic is supposed to be 20-30 years away now, why were we told in 2007 that it was only 5-6 years away?

2. If an ice-free Arctic occurred as recently as 5,500 years ago, what was the cause?

3. How do we know that we won't soon face several very cold winters in a row?