A man with hat and warm clothing puts a silver cylinder on a huge shelf with similar containers.

The largest ice drilling archive in the world is to get an upgrade: its cooling system changes from prohibited coolant that can damage the ozone layer to a more environmentally friendly technology.

”the ultimate Cold materials Through ozone-saving solutions is a very important, legally driven topic, ”says Tas van Umment, a climate scientist from Hobart, Australia, the co-chair of the international partnerships in ice core sciences.

ice scales

The ICE Core Facility of the US National Science Foundation (NSF-ICF) in Denver, Colorado, houses around 25,000 meters of ice drilling nuclei, all of which were drilled with NSF financing since the facility opened in 1993. This includes the core of the vostok station in the Antarctic 1 Oldest continuous ice, as well as new nuclei from the Allan Hills of Antarctic, which contain the oldest of each promoted ice and are millions of years old. "You are a hot good," says Curt Labombard, curator of the facility.

such nuclei contain Trapped air, particles and chemical isotopes that provide information about the past atmospheric composition and temperatures as well as events such as volcanic eruptions. As a rule, removed cores are cut into sections, with some sections analyzed by researchers and others are kept in an archive for later examination.

The 1500-cubic meter freezing chest of the Denver archive is held on icy -36 ºC. How many household cooling cabinets and air conditioning systems that were built in the 1990s are based on a refrigerant called hydrochloro fluorine hydrogen (HCFC).

forbidden coolant

Lecks of HCFCs from production facilities or devices can destroy the protective ozone layer of the earth . Therefore like their more destructive offspring, the hydrocarbons (CFCs), HCFCs gradually banned . The Montreal protocol passed in 1987 to save the ozone layer prohibited the new HCFC production in wealthy countries after 2020 and after 2030 in poorer countries.

That is why many newer refrigerators and climate systems use hydrofluoro-fluoring hydrogen (HFCS), which are much less problematic for the ozone layer than HCFCs, but can be strong greenhouse gases -up to 15,000 times more than carbon dioxide. Two other large ice drilling nuclei archive facilities, the Canadian Ice Core Lab at the University of Alberta in Edmonton and the European ice drilling facility at the Alfred Wegener Institute in Bremerhaven, Germany, use HFCS.

but also HFCs are gradually dismantled according to a change in the Montreal protocol from 2016, whereby chemists and companies are looking for “replacement for the substitutes”, says Mark McLinden, who examines the U.S. National Institute for Standards and Technology in Boulder, Colorado, refurbishment.

The breakdown rules apply to new devices, not for existing, but Labombard says that the operators of the NSF facility felt that the time had come for an upgrade. The decades-old freezer is inefficient, its software is outdated and the costs for maintenance and repair are increasing, says Michael Jackson, program manager for Antarctic Erd sciences at the NSF, which leads the renovation .

future -proof refrigerant

common options for replacement refrigerants that are not damage to the ozone layer and are less powerful greenhouse gases are hydrofluorolefines, propane, ammonia and co . All have their advantages and disadvantages, including that some are poisonous or flammable. Another large ice drilling core deposit, in Japan, uses ammonia. The facility manager of the Denver Archives have chosen ‘transcritical’ CO 2 , which can behave at the same time like a gas and a liquid-an increasingly popular option for efficient commercial refrigeration systems. Jackson says that Co 2 , although it is a greenhouse gas, cannot be flammable and “is more efficient at low operating temperatures”, and adds that “it is difficult to quantify, but Co the most future -proof refrigerant at low temperature seems to be.

Working on the new NSF freezer should begin in August and be completed in the first quarter of 2026.

Various universities keep their own ice drilling nuclei in smaller cooling stores. Some observe with interest on how the renovation of the NSF-ICF works, because they too have to replace outdated refrigerants. "We are in the same boat," says Ellen Mosley-Thompson, paleo climatologist at Ohio State University in Columbus. Labombard says that the team in Denver is ready and willing to help others. “ We have offered help and would like to share our experiences,” he says.