Nature Geoscience 6, 339–346 (2013); published online 21 April 2013; corrected after print 26 April 2013.

In the version of this Progress Article originally pubished, the authorship pseudonym was incorrectly stated as the PAGES 2k Network. The correct name is the PAGES 2k Consortium, referring to a group of authors (from within the more extensive PAGES 2k Network) who temporarily worked together for the purpose of producing this paper. This has been corrected in the PDF and HTML versions.