Three sediment cores were collected along the West Antarctic Peninsula during RRS James Clark Ross expedition JR15003. Pb-210 analyses of sediment samples were carried out at GAU-Radioanalytical Laboratories, National Oceanography Centre, Southampton. The samples were measured by alpha spectrometry of Po-210, a proxy method that gives the activity of Pb-210, as Po-210 is a granddaughter of Pb-210 (Appleby, 2008; doi:10.1177/0959683607085598). The sediment samples were almost 2 years old, so it was assumed Pb-210 had reached secular equilibrium with Po-210 (half-life = 138 days) within the sediment (Baskaran, 2011; doi:10.1016/j.jenvrad.2010.10.007 and San Miguel et al., 2002; doi:10.1016/S0168-9002(02)01415-8).