GeoMag

I C E C O R E S O F G R E E N L A N D

ROBERT COOMBE

ICE CORES OF GREENLAND

Celsius. When examining the ice cores, scientists look for three important details: the ratio of different oxygen and hydrogen isotopes to indicate former temperatures; the air bubbles in the core can be analysed to see the methane and carbon dioxide concentrations; and the radioactive elements (artificial or natural) in the ice can be studied to determine the date of the layers of ice. The data provided by the ice cores can then be compared with data from the present day, to help us analyse trends in temperature and greenhouse gas levels. Most of our data to prove climate change derives from ice cores, and this is due to the physical nature of their being layers of ice. Given that the lower down layers of ice have literally frozen data from years in the past, they act as an extremely reliable measure. A problem we may face in the future is that as ice sheets melt the central scientific evidence to plot the climate of the past disappears with it. Thus, it is imperative, that ice cores continue to be cored, stored and examined as soon there may be significantly less ice for us to analyse!

Ice Cores of Greenland Ice Cores are one the best ways for today’s climatologists to reconstruct the climate of the past, and prove to its many sceptics, that anthropogenic climate change is a real phenomenon and that carbon dioxide concentrations and the average global temperature are rising. Greenland is one of the best spots to collect and examine ice cores. Due to its vast size and very low population density, 0.028 people per square kilometre, most of Greenland’s ice sheets and glaciers have been untouched by humans and are well preserved and uncontaminated. Greenland’s ice cores can be used to measure the climate up to 130,000 years ago. 79% of Greenland is covered in ice, making it a playground for climatologists trying to uncover the climate of earlier periods of the Quaternary. Ice is split into layers, and the Ice at the top of the sheet is the snow that has fallen most recently, but the further down you go into the ice sheet, the further back in time you go. The ice at the bottom layer of the sheet is from snow that would have fallen many millennia ago, and that ice can provide us vital information about the temperature and carbon dioxide levels in the past. At its thickest, the Greenland Ice Sheet is three kilometres deep, and scientists are desperate to try to retrieve ice right at the bottom of the layer, as it will provide us with an image of the climate much longer ago. The problem is that the drills can only dig out ice cores at a of max six metres in length at a time, and due to the freezing conditions in Greenland, it makes it hard for scientists to drill for extensive periods of time. Nevertheless, after 500 drills or so, ice cores formed up to 130,000 years ago are drilled out, transported, and then stored by universities and labs to be examined. Projects like the Greenland Ice Sheet Project and the East Greenland Ice Core Project have been established, with funding from US and Swiss science foundations, to carry out the drilling and experiments. The ice cores are often shipped back to the US and stored in the National Science Foundation’s great big ice core ‘freezer’, which is 55,000 cubic feet in size and is held at -36 degrees

22 | Geographical Magazine • Merchant Taylors’ School

2021/22 Edition | 23