Arctic sea ice in IPCC climate scenarios in view of the 2007 record low sea ice event

In September 2007, the Arctic sea ice extent reached a new record low of 4 million km2, about 1 million km2 lower than the preceding record low in 2005. The 2007 event is unprecedented in observed history. Here we try to summarize the current state of the discussion regarding the causes of this event and to which extent a prediction of such extreme events by models can be expected.