Nature 536, 411–418 (2016); doi:10.1038/nature19082

After publication, we were notified by E. Hawkins that there were errors in the source data file for Fig. 2 of this Article. The errors arose during the transcription from Matlab to Excel, and have no effect on the results or figures. There are two corrections, to columns A–C in sheets ‘panel_a’ and ‘panel_c’: (1) originally, column A incorrectly had the Antarctic, rather than Arctic, age scale; and (2) originally, because of the incorrect age scale, part of column B appeared in column C. The Supplementary Information to this Corrigendum contains the corrected source data file for the original Fig. 2. The original Article has not been corrected online.