That would make ice cores a record of those specific locations rather than a broader measure of the sea where the evaporation occurred. (theinconvenientskeptic.com)
The current rate of CO2 rise in atmospheric concentrations is unprecedented with respect to the highest resolution ice core records which cover the last 22,000 years. (metlink.org)
Ice core records prove that current levels of carbon dioxide and methane, both important greenhouse gases, are higher than any previous level in the past 400,000 years. (earthobservatory.nasa.gov)