Plants emerging from beneath melting Canadian ice caps

Noting that the plateau ice caps of Baffin Island, Arctic Canada, are sensitive indicators of climate, Anderson et al. analyze aerial imagery and find that ice cover has diminished by more than 50 percent since 1958. Linear projections suggest that all ice caps on the island's plateau will disappear by 2070 A.D. From radiocarbon dating of dead vegetation that has emerged as ice margins have receded, the authors find that ice caps are now the smallest that they have been since at least 350 A.D. Cosmogenic radiocarbon accumulating in exposed rocks, which reveals their postglacial exposure history, shows that the plateau supported ice caps for most of the past 2800 years, accentuating the anomalous nature of twentieth-century warmth. Periods of widespread ice cap expansion during the Little Ice Age coincide with peak levels of volcanic aerosols in the stratosphere and reduced solar luminosity, suggesting a trigger mechanism for the Little Ice Age. The current warming exceeds any sustained warm episode in this area for at least the past 1600 years.-American Geophysical Unionws