Report: ‘Arctic Ice Almost As Extensive As It Was 42 Years Ago in 1971’
Green shows current ice. Red shows 1971 ice.
The IPCC report from 1990 showed that ice extent was low in the early 1970s.
www.ipcc.ch/ipccreports/far/wg_I/ipcc_far_wg_I_full_report.pdf
NCAR also noted that prior to 1972, ice extent was low.