Drilling for the oldest ice

Using new drill technology scientists are now searching for the best place in Antarctica to obtain the oldest ice core ever drilled.

More than a decade ago, the European Project for Ice Coring in Antarctica (EPICA) drilled the oldest existing core, which contains 800,000-year-old ice, from an ice dome in East Antarctica known as Dome C. The core reaches only as far back as the latter part of the Pleistocene epoch, when Earth began cycling between warm and cold periods every 100,000 years. Before 1 million years ago, the cycle occurred every 40,000 years (L. E. Lisiecki and M. E. Raymo Paleoceanography 20, PA1003; 2005), so scientists want an ice core that is twice as old as EPICA to better understand this transition.

Digging such a core would cost about US$50 million and take several years, so researchers want to be sure that the location is optimal — with ice that is sufficiently deep but not melted at the bottom by geothermal activity. “It’s absolutely crucial to thoroughly investigate all options,” says Eisen. Enter a new breed of drill, designed to do fast, cheap reconnaissance instead of extracting a single, intact ice core, as previous deep drills have done.

One promising location, ‘little Dome C’, lies just 40 kilometres away from the EPICA site — and is where the £500,000 (US$620,000) Rapid Access Isotope Drill (RAID) will start boring this month, led by climate scientist Robert Mulvaney of the British Antarctic Survey in Cambridge, UK. A narrow drill, RAID will excavate to 600 metres in about 7 days — compared with 5 years for a 3.4-kilometre core such as EPICA’s. And rather than extract a core, RAID will measure the ice’s temperature and collect chips of ice. Scientists will then comb these for clues from isotopes as to the age and temperature of the ice at the bottom of the sheet.

There is competition here as well. Another more conventional drill operation, run by Chinese scientists, has already been drilling for several years and might actually obtain a core sample 1.5 million years old first.

In a paper published today in Geophysical Research Letters, researchers studying an icecore drilled in the West Antarctic Ice Sheet have found strong evidence of the 16th century Little Ice Age in the southern hemisphere.

In a paper published today in Geophysical Research Letters, researchers studying an ice core drilled in the West Antarctic Ice Sheet have found strong evidence of the 16th century’s Little Ice Age in the southern hemisphere. From the abstract:

The temperature in the time period 1400–1800 C.E. was on average 0.52 ± 0.28°C colder than the last 100-year average. … This result is consistent with the idea that the [Little Ice Age] was a global event, probably caused by a change in solar and volcanic forcing, and was not simply a seesaw-type redistribution of heat between the hemispheres as would be predicted by some ocean-circulation hypotheses.

In an effort to emphasis human-caused global warming and eliminate any evidence of climate change caused by other factors, many global warming scientists have argued that the Little Ice Age was not a global event but merely a cooling in Europe. This data proves them wrong. The global climate has varied significantly in the recent past, and not because of human behavior. Other factors, such as fluctuations in the solar cycle, must be considered more seriously for scientists to obtain a better understanding of the Earth’s climate.