"Atmospheric concentrations of GHGs are at levels that are unprecedented in at least 800,000 years. Concentrations of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) have all shown large increases since 1750 (40%, 150% and 20%, respectively)..."
January 1, 1970
https://en.wikiquote.org/wiki/Scientific_consensus_on_climate_change