Nature 386, 818–820 (1997); doi:10.1038/386818a0

On page 819 of this Letter, the location of the coral samples was incorrectly given as 50° 25.57′ N, 46° 22.05′ W. The correct location is 50° 33.0′ N, 46° 11.6′ W. None of the conclusions are affected. We thank A. Ruffman for drawing this to our attention. Correspondence should be addressed to M.J.R. (riskmj@mcmaster.ca).