Wow, so glad he (?) qualified that with "...almost undoubtedly..." which, if I can go off on tangent here for a moment... WTF does that mean? Undoubtedly means without a doubt. Qualifying it with almost puts it back into what, the realm of well, maybe, possibly, could-be... But this {expletive} is no-doubt counting on people to read over that quickly and just remember that big word, undoubtedly. Well, it isn't, there is a lot of doubt, even from the very statements he's making.
Ok, the glacier "...has markedly sped up..." Hmm, seems to me that means more ice coming down, increased flow. Gee, to do that you'd need more snow & ice at the source... Doesn't sound like a warming trend but rather a cooling trend.
It's summer time in Antarctica......glaciers will flow faster.....basal slippage from the melting water as its base. Simple really...if they would only think about it or clarify that it is flowing faster all year round, in which case the increased cold and snow fall their would account for both.