What's sad is 60 seconds of googling would point him to a paper answering the exact question he believes cannot be answered: http://www.pnas.org/content/112/44/13508.full.pdf
>Analysis based on previously published relationships linking emissions to warming and warming to rise indicates that unabated carbon emissions up to the year 2100 would commit an eventual global sea-level rise of 4.3–9.9 m