Receding glacier, southern
Greenland. One of many glaciers on southern Greenland that has retreated (melted)
dramatically since the end of the Little Ice Age (about 1850). In front of the present ice
margin is the large brown unvegetated region formerly occupied by ice and bounded by the
"end moraine," or rocky ridge that marks the maximum Little Ice Age extent of
the glacier. Photo
credit: Jonathan Overpeck.
Muskox on Greenland. Arctic
wildlife undoubtedly have been, and will be, affected by Arctic climate and vegetation
change. Photo credit: Jonathan Overpeck.
|Arctic Environmental Change
of the Last Four Centuries
|J. Overpeck, K. Hughen, D. Hardy,
R. Bradley, R. Case, M. Douglas, B. Finney, K. Gajewski, G. Jacoby, A. Jennings, S.
Lamoureux, A. Lasca, G. MacDonald, J. Moore, M. Retelle, S. Smith, A. Wolfe, &
|Science, v. 278, n. 5341 p.
|Abstract A compilation of paleoclimate records
from lake sediments, trees, glaciers, and marine sediments provides a view of
circum-Arctic environmental variability over the last 400 years. From 1840 to the mid-20th
century, the Arctic warmed to the highest levels in four centuries. This warming ended the
Little Ice Age in the Arctic and has caused dramatic retreats of glaciers, melting
of permafrost and sea-ice, and alteration of terrestrial and lake ecosystems. Although
significant warming, particularly after 1920, was likely due to increases in atmospheric
trace-gases, the initiation of the warming in the mid-19th century suggests that increased
solar irradiance, decreased volcanic activity, and feedbacks internal to the climate
system played roles.