The GeoChristian

The Earth. Christianity. They go together.

Antarctic ice cores: a window to ice age climate change

American researchers have completed the second deepest Antarctic ice core ever drilled. Analysis of dust and entrapped air bubbles give a picture of the Earth’s atmosphere and climate over the past 100,000 years.

From the National Science Foundation: Ice Cores Yield Rich History of Climate Change — Research project completes drilling for the year, reaching two miles below West Antarctic Ice Sheet.

On Friday, Jan. 28 in Antarctica, a research team investigating the last 100,000 years of Earth’s climate history reached an important milestone completing the main ice core to a depth of 3,331 meters (10,928 feet) at West Antarctic Ice Sheet Divide (WAIS). The project will be completed over the next two years with some additional coring and borehole logging to obtain additional information and samples of the ice for the study of the climate record contained in the core.

As part of the project, begun six years ago, the team, funded by the National Science Foundation (NSF), has been drilling deep into the ice at the WAIS Divide site and recovering and analyzing ice cores for clues about how changes in the concentration of greenhouse gases in the atmosphere have influenced the Earth’s climate over time.

Friday’s milestone was reached at a depth of 3,331 meters–about two miles deep–creating the deepest ice core ever drilled by the U.S. and the second deepest ice core ever drilled by any group, second only to the ice core drilled at Russia’s Vostok Station as part of a joint French/U.S./Russian collaboration in the 1990s.

“By improving our understanding of how natural changes in greenhouse gas influenced climate in the past, the science community will be able to do a better job of predicting future climate changes caused by the emissions of greenhouse gases by human activity,” said Kendrick Taylor, chief scientist for the WAIS Divide Ice Core Project.

The drilling site is about 966 kilometers (600 miles) from the South Pole, at an ice divide (which is analogous to a watershed divide) in West Antarctica, where the ice is flowing out to the sea in opposing directions.

“This location was selected because it is the best place on the planet to determine how greenhouse gases have changed during the last 100,000 years” said Taylor. Since it began, the WAIS Divide Ice Core Project has continuously collected ice from the surface down to a depth of 3,331 meters. The ice at this depth fell as snow about 100,000 years ago. The high annual snowfall at the site enables individual annual layers of snowfall to be identified and counted (much like counting tree rings) back to about 40,000 years. Below that, the layers become too compressed to allow annual layers to be resolved. Scientists hope for at least decadal resolution to this point, sufficient for the science goals to be achieved.

——————————

The drilling ceased 100 meters (328 feet) above the contact between the ice and the underlying rock, to avoid contaminating a possible water layer at the ice-rock contact. The basal water system may consist of water-saturated, ground-up rock, and has not been exposed to the earth’s surface for millions of years. It may harbor a unique and pristine biological environment that the U.S. Antarctic Program does not wish to contaminate.

A few thoughts:

  • We cannot understand climate change—natural or human-induced—without understanding the geologic past. Quaternary (ice age) history gives us a baseline for understanding the present.
  • It may be bitter cold on the surface of Antarctica, but much of the Antarctic ice cap is warm-based, meaning that the ice-rock boundary is wet rather than having the ice frozen to the rock substrate. Just like anywhere else in the Earth’s crust, there is a geothermal gradient within the ice. The deeper you go in the ice, the warmer the temperature, and three kilometers of ice is plenty thick to go from way below zero up to the melting point of ice.
  • Young-Earth creationists try to explain the origin of the Antarctic ice sheet as a post-flood event within the past 4500 years. A thorough rebuttal is found at the Answers in Creation site.

Grace and Peace

February 17, 2011 Posted by | Climate Change, Geology | , , | Leave a comment