Dear Dr. Melia, thank you for your revised manuscript. While I am generally satisfied with most of the edits in response to the reviewer's concerns, I have a few concerns that require addressing before accepting the manuscript for publication in The Cryosphere.

As the reviewer's noted, it's incorrect to equate reduction in model-spread with a reduction in uncertainty. Note when bias correcting with regards to SIT, this will be especially true as the models tend to have high spatial correlation between each other in terms of their SIT, and not with the observations (see Stroeve et. al. 2014, The Cryosphere). On line 22 of the introduction I do not think it's correct to then state you explore how the uncertainty in SIT projections is reduced through bias correction, it is the spread that is reduced. The same on page 28, line 2 and elsewhere. I think it is important to make a very clear distinction between the two and do not equate them on page 30 (line 1) or elsewhere.

Reviewers are also concerned about referring to PIOMAS as observations. So online 27, the statement observationally-based estimate of SIT from PIOMAS is incorrect. Yes observations of SIC go into forcing PIOMAS but it is still a model and it does have biases with respect to the observations (again see Stroeve et al. 2014), and interestingly PIOMAS agrees more closely with the CMIP5 models than with the observations in terms of spatial pattern correlation,which in turn will impact your bias correction. On line 27 (section 2.1), I would instead rewrite to state modeled SIT with the coupled ice-ocean PIOMAS model, driven by observations of SIC, reanalysis data. etc. Similarly on line 14, page 21, you should say "estimates" instead of "observations". You may also want to address the issue of PIOMAS thickness patterns being better correlated with CMIP5 models than with the observations in section 4.4. One thing that stands out for example in Figure 6 is that your ice is too thin for the thick ice regions (i.e. north of Greenland and the CAA), which is true also in PIOMAS.



I am curious about how thin the SIT is in September. Most evaluations between observations and PIOMAS have been in spring. Having thickness only up to 1.5m in the CAA seems too thin as this is the old MYI region and winter ice thickness typically exceed 5m. That would suggest 4m of summer melt. Can you say anything about validation of these thickness in September?

Section 3, first paragraph, this isn't quite correct. There are publications that have made estimates of how much the loss of sea ice is a result of GHGs vs natural variability (see Notz et al., 2013, Notz, 2015). Stroeve et al., 2012 also provide an estimate as does Kay et al., 2011.

Also I would be cautious about saying ice age correlates with thickness. While Maslanik et al., 2007 did show correspondence, adding on two more years of ICESat data shows this correlation breaks down.