melt events have occurred at Summit in the past and I have quoted the longest-term average frequency of ~150 years (exactly 153 from the paper) over the past 10,000
The unprecedented melt has happened 65 times in the last 10,000 years. But it is worse than it seems. If there was any significant melting, the albedo of the ice surface would have dropped off visibly and dramatically. It didn’t change at all.
Every skier can tell the difference between fresh unmelted snow and melting snow. Fresh snow is very bright – and you need sunglasses. Melting snow is much darker. The snow on top of most of the ice sheet shows no sign of melt.
Look how much brighter the snow on Greenland is, than the sea ice to the north.