The Arctic is melting faster than expected.

Due to insufficient data of temperatures in the Arctic region, prior climate change models failed to factor in 19 percent of worldwide air temperature heating over the last 150 years. While scientists have been aware of the exclusion of precise historical numbers up north, the community believed that the effects of the temperature change was relatively small on its own, but were surprised with the aggregate heating effect of the figures.

Source: http://phys.org/news/2016-07-historical-global-nasa.html