[mark-r]

The ice that's melting today is floating ice in the Arctic and Antarctic, because it's subject to warm ocean currents. Floating ice doesn't change sea levels when it melts. The ice that matters is the glaciers in Greenland and Antarctica. Glaciers weren't formed in a day, and they won't melt in a day either.

[needcheapbw]

That is correct. Glaciers melt constantly, new snow forms as moisture accumulates in higher elevations and condenses, falling as snow. The snow becomes the beginning of the glacier. It's a cycle that repeats. It is repeating right now, every year.

https://nsidc.org/cryosphere/glaciers/life-glacier.html

https://www.iceagenow.com/List_of_Expanding_Glaciers.htm

http://www.esa.int/spaceinimages/Images/2016/11/Pio_XI_Glaci...