Authors: M Sigl; M Winstrup; J R McConnell; K C Welten; G Plunkett; F Ludlow; U Büntgen; M Caffee; N Chellman; D Dahl-Jensen; H Fischer; S Kipfstuhl; C Kostick; O J Maselli; F Mekhaldi; R Mulvaney; R Muscheler; D R Pasteris; J R Pilcher; M Salzer; S Schüpbach; J P Steffensen; B M Vinther; T E Woodruff Journal: Nature Date: 2015-07-08 Impact factor: 49.962