Read here. We've had several postings on Heidi who never seems to be at the top of her scientific game, if she ever had one. She is truly either a bimbo dimwit or a serial liar BS'er regarding sea levels.
As can be seen here or here, there is absolutely no empirical evidence (note: 3mm/year equals 12 inches/century; since 2006 seas have risen at 0.76mm/year rate) that comes anywhere close to her projection of a 3-foot rise in sea levels. Her testimony in Congress should be assessed for what it is: rantings of a bimbo inclined to exaggerate, without empirical merit.