In 2006 scientists were predicting that the north polar ice cap would be totally gone (melted) in summer time by the year 2050 if we did not change our levels of greenhouse gas emissions radically and quickly.

By January of 2007, with new data at hand, the prediction became that 2020 was the year by which the north polar ice cap would be completely gone in summer.  Here are the source links:

• Reuters - Arctic ice cap melting 30 years ahead of forecast
• ECCHO - Arctic ice cap melting 30 years early
• UN Environment Programme - Polar maps