"Mark Serreze, the director of the NSIDC, said that making a clear separation between manmade and natural factors is “very difficult""; Stroeve: "In our climate model simulations we don’t see evidence of a tipping point"

In Wake of Sea Ice Loss, Focus on New Models, Melt Ponds | Climate Central

“... The argument that the ice loss is outpacing model projections no longer seems to be true,” said Marika Holland, a researcher at the National Center for Atmospheric Research, in an email conversation.

Recent studies have also zeroed in on the relative contribution of manmade global warming to sea ice loss compared to natural climate factors. The research has shown that manmade global warming is likely responsible for 50 to 60 percent of Arctic sea ice decline during the satellite era. Mark Serreze, the director of the NSIDC, said that making a clear separation between manmade and natural factors is “very difficult,” since as the sea ice thins, it become more vulnerable to melting spurred by weather patterns.
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Stroeve said that sea ice volume, which incorporates measurements of ice extent as well as thickness, is a more important metric than sea ice extent alone. Ice extent, she said, will exhibit considerable variability even after the arrival of ice-free summers, whereas ice volume trends would be more consistent. “Because you could have an anomalously cold summer that allows a thin layer of ice to remain and increase the extent. In our climate model simulations we don’t see evidence of a tipping point, so it appears that even though the Arctic may become ice-free, the ice could also recover for a few years.”