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A key pacemaker of ice ages on the Earth is climatic forcing due to variations in planetary orbital parameters. Recent Mars exploration has revealed dusty, water-ice-rich mantling deposits that are layered, metres thick and latitude dependent, occurring in both hemispheres from mid-latitudes to the poles. Here we show evidence that these deposits formed during a geologically recent ice age that occurred from about 2.1 to 0.4 Myr ago. The deposits were emplaced symmetrically down to latitudes of ~30°-equivalent to Saudi Arabia and the southern United States on the Earth-in response to the changing stability of water ice and dust during variations in obliquity (the angle between Mars' pole of rotation and the ecliptic plane) reaching 30-35°. Mars is at present in an ‘interglacial’ period, and the ice-rich deposits are undergoing reworking, degradation and retreat in response to the current instability of near-surface ice. Unlike the Earth, martian ice ages are characterized by warmer polar climates and enhanced equatorward transport of atmospheric water and dust to produce widespread smooth deposits down to mid-latitudes. [ABSTRACT FROM AUTHOR]

Analyzes backscatter images and sub-bottom profiler records obtained during the 1999 expedition of the SCICEX submarine in the Arctic Ocean. Discovery of multiple bedforms indicative of glacial scouring and moulding of the sea floor, combined with large-scale erosion of submarine ridge crests; How these distinct glaciogenic features demonstrate that immense, Antarctic-type ice shelves of up to 1 kilometer thick and hundreds of kilometers long existed in the Arctic Ocean during Pleistocene glaciations.

Examines the new ice core from Greenland yielding the first high-resolution picture of the start of the last ice age in the Northern Hemisphere. Prevention of the cores from revealing either the onset of ther glacial period or events during the preceding warm interglacial period by structural disturbance of the deepest ices; Location of the North Greenland Ice Core Project core in a volcanic center; Reduction of the thinning of deep ice layers.