A worrying report regarding the retreat of ice on the Arctic Ocean has just been published by the National Snow and Ice Data Center in Boulder, Colorado.

Due to the warmth of the summer, the retreat of the ice is an annual occurence. However, this year it shrank by more than a million square miles - an area about six times that of California - leaving it below the average minimum ice area of recent decades. 

Several scientists, inlcuding Igor Polyakov, an ice expert at the University of Alaska, have studied satellite imagery going back many years and believe that a retreat this size likely never occurred at any point during the last century.

Dr. Serreze, a senior researcher at the ice center, believes the current ice patterns can no longer be put down to natural variability. "We're starting to see the system respond to global warming," he said.

At the same time, he and other scientists understand that ice patterns are extremely complex affairs, and as a result it is impossible to say with 100% certainty how human and natural factors are affecting these patterns.

But the findings of the ice center are certainly causing many observers to sit up and take notice.