Armed with aerial photos that reveal these trimlines, the researchers mapped the past and present sizes of the ice sheet in a 3D computer model. (carbonbrief.org)
So, while the specific size of the ice sheet was different, the overall conditions are degraded in ways not likely to have existed in the past all at the same time. (realclimate.org)
There are more, however, including the amount of sunlight an ice sheet is able to reflect; the larger an ice sheet, the more sunlight is reflected, but the smaller an ice sheet, the more ocean there is surrounding the ice sheet to absorb the sunlight which in turn heats up the surrounding waters increasing the melt which decreases the size of the ice sheet which in turn... and so goes the cycle. (relevantmagazine.com)