You’ve probably seen pictures of stranded polar bears and heard
that global warming is causing the melting of Arctic sea ice —
that is, floating ice formed from freezing ocean surface water.
But you may imagine, as most people do, that this distant
phenomenon is unfolding gradually over a centuries-long time
frame. Julienne Stroeve, a climate scientist at the National
Snow and Ice Data Center in Boulder, Colo., has compiled
detailed measurements that melt away any such misconceptions.
Stroeve is closely monitoring the extent of Arctic sea ice, and
her research shows that dramatic changes are occurring right now
— far faster than most experts anticipated and with enormous
consequences for the whole planet, not just the Arctic region.
For instance, during the warmest part of 2010, the total amount
of Arctic sea ice — the so-called “seasonal minimum” — was the
third-smallest ever recorded. The smallest and second-smallest
seasonal minimums were measured in 2007 and 2008, respectively.
Natural variability, includ