September 15, 2000
This photograph near the North Pole was taken in late April of 1999. There was still plenty of ice at the north pole then - it's about 4 m thick. Perhaps you've heard reports that there was no ice at the North Pole on one day this summer when a tourist ship was able to cruise all of the way to the pole. In a normal summer, only about 90% of the ice north of 80 degrees north latitude is ice-covered. Large fractures or leads always occur each year when the ice deteriorates as summer progresses. The motion of the winds and the force of the ocean currents play a big role in determining where and when the ice opens up. So water at the pole may be a matter of happenstance and may not in itself be a source of concern.
Since the 1970s, the extent of the Arctic sea ice has been retreating about 1/4 of 1% per year based on analyses of satellite observations made by Claire Parkinson, Don Cavalieri, Per Gloersen, Joey Comiso and Jay Zwally at Goddard Space Flight Center. It should be mentioned that when the Arctic sea ice melts in summer, sea level doesn't rise. The sea ice is already floating on water and is in equilibrium with it. The concern, though, is that sea ice plays an important role in controlling climate, and the amount of open water and ice affects how much energy is absorbed and reflected back to space. With more open water, more energy would be absorbed by the water and less reflected back to space. Consequently, temperatures would be expected to increase even more.
Is the Arctic sea ice declining in more recent years? Yes. Was there open water at the North Pole this summer? Yes, at least on some days. The response seems to be that we should be uneasy about the former but not alarmed by the latter.