 The IPCC's sixth assessment report found that the Arctic will likely become nearly completely ice-free in September within the next few decades due to rising levels of greenhouse gases. This conclusion was reached after comparing observations with computer simulations of climate change. The simulations were adjusted to better reflect the observed changes in Arctic sea ice, which revealed that the Arctic could become ice-free much sooner than previously thought. This article was authored by Yanhee Kim, Sunky Minit, Nathan P. Gillett, and others.