A first constraint on basal melt-water production of the Greenland ice sheet by Karlsson, NB, Solgaard, AM, Mankoff, KD, Gillet-Chaulet, F, MacGregor, JA, Box, JE, Citterio, M, Colgan, WT, Larsen, SH, Kjeldsen, KK, Korsgaard, NJ, Benn, DI, Hewitt, IJ, Fausto, RS