Decrease in Arctic Sea Ice
Arctic Sea Ice is declining annually at a rate of approximately 9.3% per decade. Although melting of sea ice does not change the level of the oceans directly, it nonetheless does occur because of global atmospheric warming, and that has major implications for the continental ice sheets in Greenland and Antarctica. If those were to melt entirely, it would cause the oceans to rise approximately 70 meters and would result in massive flooding in the world's highly populated coastal areas.
NOAA Arctic Report 2017
The following video is from the Arctic Program of the National Oceanic and Atmospheric Administration website