The low pass frequency filtering
due to the century long compaction time of the
snow crystals in the firn and the effects of the pressure on the air inclusions (both during the closing of air - paths in the firn and during the withdrawal of the ice core) significantly change the amplitude and phase of the CO2 content of the ice core with
respect to the isotopic content of the surrounding ice.
With
respect to Judith Curry: I will ask her
to give references
to better underpin her claims (for example on the claim that albedo increase on land
due to more
snow is compensating for the albedo decrease above the arctic sea).