What you are doing here is not helpful. Yes, the Greenland ice sheet has been melting since before industrialization [1]. Yes, at current rates the ice will take 10,000 years to melt, as long as Jericho has been a city [2].

Productive responses to these claims include: Greenland's rate of melting has dramatically accelerated since industrialization and will likely continue accelerating as atmospheric carbon rises further.

and

Even losing a small percentage of the ice sheet will have devastating consequences in some regions.

These responses have a remote shot at making someone think about their position and whether it makes sense. Snarky answers where you accuse someone of ignorance over their informed claims only make you and your side look bad. I'm on your side, and I don't care for it.

[1] https://www.nationalgeographic.com/science/article/greenland...

[2] A little more tricky, sources rightly refuse to assume constant melt rate for their models. We can eyeball this, though. https://www.smithsonianmag.com/smart-news/greenlands-oldest-... gives amount of ocean rise in the last 8 years (as of 2019) as a quarter inch, and says 25 feet total ocean rise if the whole thing melted. 4 quarter in./in. * 12 in./ft * 25 ft * 8 years = ~9600 years