摘要：In 2003, for the fi rst time, an undisturbed
Greenland ice core record
reaching further back than the glacial
period was completed. The 3090
m long ice core from NGRIP, on the
northern part of the Greenland Ice
Sheet, contains layers of snowfall
from the last 123,000 years. The
annual layers close to the surface
are 0.19 m thick, corresponding to
the present accumulation rate (in
ice equivalent) and the annual layers
at the base are all around 1 cm
thick. The basal annual layer thickness
is so well preserved due to a
basal melt of 7 mm/yr, reducing the
thinning near the bed (Dahl-Jensen
et al., 2003). This very high-resolution
record contains 1490 m of ice
from the present interglacial period
(0-11,703 yr b2k (before AD 2000)),
1600 m of ice from the glacial period
(11,703-115,000 yr b2k) and 90 m of
ice from the last interglacial period,
the Eemian climatic period (NGRIP
members, 2004)
