Supplement to: Rhodes, Rachael H; Brook, Edward J; Chiang, John C H; Blunier, Thomas; Maselli, Olivia J; McConnell, Joseph R; Romanini, Daniele; Severinghaus, Jeffrey P (2015): Enhanced tropical methane production in response to iceberg discharge in the North Atlantic. Science, 348(6238), 1016-1019, https://doi.org/10.1126/science.1262005