Read here. Empirical-based scientists conducted real-world field research and determined that summer Arctic ice has been less than 50% than that during most modern summers. This clearly indicates that summers were definitely warmer in the recent past, despite the low levels of CO2.
BTW, this means polar bears survived this extreme ice shrinkage in the past and will do so again.
It also conclusively proves that the infamous disappearing sea ice "tipping point" that IPCC climate alarmist scientists claim is lurking in the next heat wave is likely non-existent - just like the scary boogieman living underneath the bed of children.
From the peer-reviewed study by Funder et al.:
"For several thousand years, there was much less sea ice in The Arctic Ocean – probably less than half of current amounts. This is indicated by new findings by the Danish National Research Foundation for Geogenetics at the University of Copenhagen...when the temperatures were somewhat warmer than today, there was significantly less sea ice in the Arctic Ocean, probably less than 50% of the summer 2007 coverage, which was absolutely lowest on record...The good news is that even with a reduction to less than 50% of the current amount of sea ice the ice will not reach a point of no return: a level where the ice no longer can regenerate itself even if the climate was to return to cooler temperatures. Finally, our studies show that the changes to a large degree are caused by the effect that temperature has on the prevailing wind systems. This has not been sufficiently taken into account when forecasting the imminent disappearance of the ice, as often portrayed in the media,”" [Svend Funder, Hugues Goosse, Hans Jepsen, Eigil Kaas, Kurt H. Kjær, Niels J. Korsgaard, Nicolaj K. Larsen, Hans Linderson, Astrid Lyså, Per Möller, Jesper Olsen, Eske Willerslev 201: Science]
Previous glacier/sea-ice and peer-reviewed postings.