A very popular point puts changes of the Arctic sea ice into a historic perspective and claims 'there always have been natural variations'. Just like ebb and flow sea ice will come and go - nothing special.

The opposite states the abstract of the 'History of sea ice in the Arctic':

The current reduction in Arctic ice cover started in the late 19th century, consistent with the rapidly warming climate, and became very pronounced over the last three decades. This ice loss appears to be unmatched over at least the last few thousand years and unexplainable by any of the known natural variabilities.

The question is how does the signal of recent decline compares to known variations and a new papers by Christophe Kinnard and colleagues nicely visualizes this aspect. 'Reconstructed changes in Arctic sea ice over the past 1,450 years' describes the use of a network of high-resolution terrestrial proxies from the circum-Arctic region to reconstruct past extents of summer sea ice.

Check out the course of the top curve and then try to accept the Deluge as a matter of ebb and flow.

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