The new discovery indicates that even during the warmest periods since the ice sheet formed, the centre of Greenland remained stable, allowing the landscape to be locked away, unmodified, under ice through millions of years of cyclical warming and cooling.
Understanding how Greenland's ice sheet behaved in the past, and in particular, how much of the ice sheet melted during previous warm periods as well as how it re-grew is important to developing a scientific understanding of how the ice sheet might behave in the future.
As global average temperatures rise, scientists are concerned about how the ice sheets in Greenland and Antarctica will respond.
Vast amounts of freshwater are stored in the ice and may be released by melting, which would raise sea levels, perhaps by many meters.
The magnitude and rate of sea level rise are unknown factors in climate models.
The study will appear in the forthcoming issue of the journal Science.
