Why since the end of November 2007, is Arctic sea ice volume is up 15 percent from 13,000 km³ to 15,000 km³?

http://ocean.dmi.dk/arctic/icethickness/anim/plots_uk/CICE_combine_thick_SM_EN_20071130.png

http://ocean.dmi.dk/arctic/icethickness/anim/plots_uk/CICE_combine_thick_SM_EN_20171130.png
15 answers 15