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NASA ice expert Claire Parkinson does the math on global sea ice and confirms that small gains around Antarctica do not cancel out large losses in the Arctic.

In 2011, annual snow cover extent over Northern Hemisphere continents (including the Greenland ice sheet) averaged 24.7 million square kilometers, which is 0.3 million square kilometers less than the long-term average.

Records from the last five decades show that on average, spring snow is disappearing earlier in the year than it did in the past.