Ice core data - Ice Ages and Interglacials: Measurements, Interpretation, and Models - page 134

4
Ice core data
Oard (2005) provides an excellent introductory overview of ice cores from the
ice sheets at Greenland and Antarctica. The two great ice sheets presently existent
on Earth are located where landmasses exist near the poles: Greenland and
Antarctica. Both ice sheets store a huge amount of water, as indicated in Table
4.1 . If the Antarctic ice sheet were to fully melt, the ocean level would rise about
68 meters. Full melting of the Greenland ice sheet would add another 7 meters.
Since the average depth of the oceans is about 3,800 meters, there is considerably
more water in the oceans than there is tied up in the ice sheets. However, the ice
sheets account for about half the fresh water on the planet.
4.1 GREENLAND ICE CORE HISTORICAL TEMPERATURES
Figure 4.1 provides a rough topographical map showing the locations of several
major ice core sites on Greenland. The characteristics of the various drilling sites
are summarized in Table 4.2 . Annual snowfall varies from over 70 cm/year of
water (equivalent) in the extreme south, to 30-50 cm/year in the lower to mid
range, to 10-30 cm/year in the north. At the highest point on Greenland, the
annual mean temperature is 30 C, varying between 15 C in midsummer to
41 C in midwinter.
The Joint European Greenland Ice Core Project (GRIP) drilled a 3,029m ice
core down to bedrock in central Greenland from 1989 to 1992 at 72 N. The ice
cores contained records of past climate—temperature, precipitation, gas content,
chemical composition, and other properties.
After five years of drilling, the Greenland Ice Sheet Project-2 (GISP2)
penetrated through the ice sheet and 1.6m into bedrock in July, 1993, recovering
an ice core 3,053 meters in depth, about 28 km from GRIP. This was the deepest