Taku Glacier is the largest glacier draining the Juneau Icefield, and
reaches tidewater near the mouth of the Taku River. Taku Glacier histo
rically calved icebergs into a 100-m-deep tidal basin but presently te
rminates on its shoal moraine and outwash apron. Radiocarbon dates, de
ndrochronology, and investigations of lateral moraines indicate that f
ive major cycles of growth and recession of Taku Glacier occurred duri
ng the last 3000 yr. The timing of advances and retreats between 3000
and 2000 yr ago appear asynchronous with nearby glaciers, Those betwee
n 2000 and 100 yr ago generally coincide with land-terminating Juneau
Icefield glaciers, suggesting these events were driven by changes in g
lacier mass balance caused by regional climatic fluctuations. However,
a retreat of Taku Glacier ca. 1650 yr BP preceded retreats at nearby
glaciers by about 200 yr. In addition, since 1890 Taku Glacier has adv
anced 7.3 kin, during a period when virtually all nearby land-terminat
ing glaciers have been retreating. The history of Taku Glacier shows t
hat the behavior of tidewater glaciers can reflect climatic changes oc
curring over sustained periods of time (>100 yr), but that intrinsic d
ynamic instabilities may cause retreats and advances unrelated to clim
ate shifts.