These holes were filled with contemporary ice chart data from ships, where available, and with more recent, long-term satellite data where nothing more suitable could be sourced from the time.

BBC: Earliest satellite maps of Antarctic and Arctic sea-ice

Below is a three month price history chart comparing the stock performance of ICE vs.

FORBES: Connect

This continues a steady decline in Arctic ice volumes since 1980, as you can see in the chart below from the University of Washington.

FORBES: Move up http://i.forbesimg.com t Move down