Ice — James Follett

The top brass of Western Intelligence are badly rattled when transatlantic cables are inexplicably and provocatively cut, and Russian and American relations reach freezing-point. Only Glyn Sherwood and Julia Hammond, two scientists working in the Antarctic, can guess the identity of the enemy. It is a gargantuan slice of the glacial continent bearing millions of tons of rock on its grasp, which triggers a series of disasters as it drifts inexorably north.