If you've read the article you will have found the explanation there. The problem isn't the already floating ice, which indeed does not rise the sea level, but the land ice the floating mass is attached to.
Climate change is one contributor to the dynamics of that glacier, so yes it has a lot to do with it, but either way this has nothing to do with your original post, in which you apparently weren't even aware of the fact that the melting of the glacier would rise the sea level which your provided source also states, so I'm glad we have at least made progress on that front.
Nothing to do with cLiMaTe ChAnGe.
[0] https://www.nature.com/articles/s43247-021-00242-3 - "High geothermal heat flow beneath Thwaites Glacier in West Antarctica inferred from aeromagnetic data" - 17-Aug-2021