12/01/2019

A Frozen History Of Climate Change – In Pictures

The GuardianPhotographs Anna Filipova

Buried deep under the Greenland ice sheet is a unique archive of life on Earth 40,000 years ago. Scientists are using this information to try to predict future changes to the planet

Scientists at EastGrip are examining ice from as far back as the last ice age.


The East Greenland Ice Core Project (EastGrip) is an international science camp sited on the Greenland ice sheet, about 2,700 metres above sea level. EastGrip is run by Professors Jørgen Peder Steffensen and Dorthe Dahl-Jensen. Their task is to drill, retrieve and analyse ice cores that reach down to the bedrock.

More than 80% of Greenland is covered by ice, but the Greenland ice sheet is shrinking. The entire EastGrip camp – including tents, buildings, caves and a runway for aeroplanes – moves sideways by about 15cm per day. If the ice sheet melts entirely, the world’s sea level will increase by over seven metres, according to the latest UN World Climate Report.

Knowing how ice sheets have reacted to past and present climate changes will help scientists estimate how they will contribute to future sea level changes.

The dome is where EastGrip’s scientists go to warm up, eat and relax.

The entrance to the science trench, an ice tunnel 9.5 metres below the surface of the Greenland ice sheet.

Inside the science trench, scientists can analyse the ice without it melting. The trench’s tunnels, caves and stairwells were constructed by inflating giant balloons and slowly covering them with snow.

A freshly drilled ice core, from a depth of 1,767 metres. The ice here is about 40,000 years old, and holds unique archives of past atmospheric conditions, including temperature, volcanic eruptions and greenhouse gas concentrations.  

The scientists cut and examine the ice cores inside the science trench, testing for volcanic ash, acid and ice crystal properties.  

Once the ice cores are drilled, they are logged in a refrigerated room at -35C (-31F) to prevent breaks.  

The scientists at EastGrip are now delving into ice from the last ice age, which is about 40,000 years old.  

Peder Steffensen explains: ‘The ice sheets in Greenland and Antarctica are unique as they are the only ones where the interior temperatures rarely (almost never) reach melting point during the summer. Snow remains snow, it does not melt away.’ As snowflakes hold small bubbles of air, their compressed layers are a timeline of information, he says – much like tree rings.  

Thirty people live and work at the camp during the summer months, when the temperature varies between –10C and -25C.  

A senior scientist collects fresh snow. Dr Barbara Seth, a driller at the camp, said: ‘Generally, everything is very intense in the field ... you are in an extreme and remote environment with nothing other than ice reaching far off into the horizon.’  

To get drinking water at the camp, scientists must melt snow from the ice sheet.  

There is no luxury transport for EastGrip’s scientists.  

Red flags attached to bamboo poles mark the boundaries of the camp for when visibility is low.  

All of the scientists’ food and equipment is flown in by the LC-130 Hercules, operated by the US Air National Guard. It is ski-equipped and lands directly on the ice sheet.

Links

No comments :

Post a comment

Lethal Heating is a citizens' initiative