The recent increase in flow of outlet glaciers draining the Greenland Ice Sheet (GIS) has attracted considerable attention. Since the GIS was near its Holocene maximum extent during the Little Ice Age, how do we apportion these increases between natural retreat from the Little Ice Age and current atmosphere and ocean conditions? Ice caps adjacent to the ice sheet responded to the same climate signal as the ice sheet and may help this question.

Here we report preliminary results from two ice caps in central east Greenland. The eastern, Istorvet ice cap (70.88°N, 24.25°W), lies on the coast, beside the cold East Greenland Current. The western, Bregne ice cap (informal name, 70.90°N, 25.62°W) lies further inland. Recently emergent organic remains from > 50 sites attest to restricted extents of these glaciers. At least 15 species of plants and animals including Dryas octopetala, Saxifraga oppositifolia, and Dicristonyx torquatus indicate an ecological system similar to the present. At Istorvet ice cap these remains indicate initial thickening of the ice cap at ~AD 884 and an advance to within 500 m of the Little Ice Age extent at AD 1022 and 10Be ages from the Little Ice Age moraine it was formed at ~300 yr BP. 10Be ages of boulders on bedrock outside this moraine are ~11.0±0.3 kyr BP, confirming that this was the maximum Holocene ice cap extent. At Bregne ice cap in situ radiocarbon ages indicate a retracted ice cap from AD 1054 to 1393, followed by expansion. Cores from seven lakes draining these ice caps indicate only one expansion during the Holocene.

Our results thus far suggest that local ice caps in east Greenland were smaller than present until the last millennium as long term Holocene cooling reached critical conditions. If the GIS sheet followed this Holocene cooling pattern it implies the Little Ice Age limits represent its maximum expansion and that its increased dynamic activity currently is unique in the Holocene.