Dear Jakob,

thank your for submitting your revised manuscript and response to the reviews. Having check the revision in comparison to the reviewers’ suggestions I find that not all of their comments, especially from rev. 2, were sufficiently considered. I therefore provide you with a list of specific questions and suggestions below and ask you to consider those before I would be able to accept your manuscript for publication in TC. Looking forward to your response,

Olaf
Co-Editor in Chief, The Cryosphere


Your response stresses at several instances that your submission is intended to be a Brief Communication (BC). With the reviewers’ comments in mind I wonder if a BC is indeed the best format, or whether a normal paper would not make more sense. If you want to stick to a BC, then please make sure that the wording is very concise, unambiguous and fit and extensive elaborations for explanations could be omitted.

In the first two paragraphs rev. 2 provides a very structured criticism what should be improved in the manuscript. Your response falls short of showing what you indeed did to adequately consider them. E.g. point 2. steeper bedrock topography is briefly mentioned in the revision, but I do not find that this is the intended discussion the reviewer asked for. Please specify what you did change.
Regarding point 4., you toned down the role of the type of triggering mechanism, but it is still stressed in the abstract that you „ … hypothesize that the surge is initiated as a result of increased pressure melting caused by ice accumulation resulting in extremely high basal flow velocities.“
I find such a statement unfit for an abstract. In fact, although it is in principle alright to have some hypothesis at the end of a paper, which cannot be fully falsified or verified (as long as that is clearly stated), in the present case I find that these two possible trigger mechanisms are insufficiently discussed in the MS.
My suggestions here are
a) say in the abstract what you did and what you did (or did not) find (evidence) and
b) explain in more detail why you come to a certain conclusion, e.g. the statement on p4/l26 requires more explanation.
„... thermal switch hypothesis being at play, because …“.

Your response to rev. 2 comment on p4., l26: „we…discussed this advantage in Section 4.“: I did not see where you added or extended such a discussion, please clarify.

Figure 1:

a-c: Provide georeferenced coordinates (mandatory!). You don’t need a grid, it would be sufficient to show a couple of lat/lon ticks/labels on the border of the figure.

a-c: Add units of velocity

cross correlating -> cross-correlating Landsat …

Explain graph d please further in the caption, not too clear yet, especially the difference between the black lines and the red/yellow lines; e.g. by: "values for the quiescence have been multiplied by …, values for the build-up …“. This leads to ambiguities. A figure should be understandable from the caption alone.

insert after (yellow): both, for Landsat and Planet.

Figure 2:

„Note that … is much larger than …“
In addition to showing the original series, why didn't you take this into account by extrapolating the series from 2000-2011 into 2016 and thus calculating more realistic changes in surface elevation? I appreciate that you want to stick simply to the dates of elevation observations, but the physical point you try to make could be emphasized in this way much more, e.g. the impact on erosion rates etc.

Figure S1a: add georeferenced coordinates.

Minor comments:

p1/l32: remove extra )
p2/l19: you use two numbers, 30 and 3 m, but do not explain what they mean. Resolution, pixel size, etc.
p2/l37: remove extra )
p3/l9: Figures should be sorted according to order of appearance in the text.
p3/l18: terminus -> apparent terminus
pe/l19: add after moraine: ... dynamically decoupled from the active part of the glacier. That would take care of the rev.’s criticism.
p3/23,24: remove () from Gardelle citation.
p4/3: "Projected extents“: explicitly clarifiy of what - the lake. of what?
-> the lake. Unclear what you want to say here: if a lake would form again with a certain water level, then would you get this extent?

Dear Jakob,

thank your for revising the paper and responding to my request. I now find the paper in a more consistent and concise shape than before. I'm therefore happy to accept it for publication in TC. Nevertheless, please consider the technical corrections I ask you to apply before you submit the final version.

Regards,
Olaf


Abstract:
l13: leads -> led
l14: which is -> which were
l14 data reaveals -> data reveal

p1l26: shouldn't it be "were proposed"?
Figure 1: please mention in the caption which coordinate system is used now in the figure for georeferencing.
Figure 3: add "respectively" after "the surge" in last line.
Supplement
Figure S1: add georeferncing lines, labels and system to figure a.
Figure S2: add (red) and (black) to caption when you refer to lake volume and lake level. Green marker in b hardly visible.
p6l6 remove () from citation