General Comments

This manuscript contains valuable information and impressively comprehensive experimental results for guiding future modeling, data collection, and interpretation of Vanderford Glacier. However, currently the takeaways are not sufficiently clear, certain aspects of the methodology need to be more clearly explained and defended, and in general the manuscript needs to be edited for clarity and some technical errors.

The results here substantially contribute to the general understanding of Vanderford Glacier retreat, showing that observed calving has occurred in passive, non-buttressing ice, and did not contribute to the observed retreat rates. The authors' conclusion that basal melting likely is responsible for the observed grounding line retreat at Vanderford Glacier is important and well supported by their sensitivity testing, which suggests that high but plausible basal melt rates can reproduce observed retreat.

The authors interpret that because altimetry based estimates of melt rates are too low to reproduce observed grounding line retreat in their model, these observational datasets may be incorrect in this region. This conclusion may be valid but ought to be supported and discussed more quantitatively---two ways this analysis could be further improved are suggested in Specific Comments. 

As the manuscript discusses in a few places, there are other factors which play a significant role in the simulated grounding line dynamics, and additional observational constraints which would improve future modeling efforts, beyond the melt rate itself. The presentation of these other factors can be improved, as currently the emphasis on the melt rate as a source of error and uncertainty in the abstract and conclusion does not reflect the more balanced discussion section. I offer more specific comments on balancing the discussion of sources of error in Specific Comments.

Some of the scientific methods and assumptions need to be more clearly outlined and/or defended. These are also addressed in Specific Comments.

Specific Comments

See Supplement.

Technical Comments

See Supplement.