Glaciers: archives in danger

Scientific data obtained from studying ice cores drilled out of glaciers has substantially contributed to a universal knowledge through the understanding of our climate and environment, providing thus objective data that allows for informed decision-making for the well-being of humankind. In particular, this data provides the international community, via the IPCC (Intergovernmental Panel on Climate Change), to set the global physical context guiding transition policies needed to be implemented to curb global warming.

Still, glaciers are retreating unrelentingly, practically all over the world. This phenomenon is irreversibly altering the chemical composition of the snow strata, thus destroying the potential of these records forever, along with all hope of reconstructing the history of geochemical signals associated with climate, human activity and the biological evolution of our environment.

By the end of the century, ice-covered areas below 3,500 meters in the Alps, and 5,400 meters in the Andes will probably have disappeared.

In the firm belief that we need to start protecting this invaluable heritage right now, scientists from several nations have decided to collect samples (ice cores) from endangered glaciers so that future generations of researchers may benefit from high-quality raw material and continue to contribute to the environmental and climate science, crucial for the future of humanity.

Understanding past environments to anticipate future change

When drilling down through the glacier to bedrock, each of the layers of snow and ice that we pass through represents the state of the climate and the atmosphere over a successive period of years, and they are the only natural record of it that we have. The deepest layers are also the oldest, dating back from a century to a few millennia. Sometimes, at the base of these glaciers, you can even find layers formed during the Last Glacial Maximum approximately 20,000 years ago.

Analysis of ice cores allows us to reconstruct past changes in the climate, the environment and in particular, the atmospheric composition: temperature variations, atmospheric concentrations of greenhouse gases, emissions of natural aerosols or man-made pollutants, etc.

Ice offers a unique insight, especially when it comes to the increase in atmospheric pollution over the past century, by highlighting regional disparities as well as characterizing the origin of that pollution.

Damages already visible

The Alps

Glaciers in the Alps are vital European observation points. Truly high-altitude laboratories, alpine glaciers have long been the subject of studies. Their recent accelerated retreat is clearly linked to global warming. In the center of an industrialized Europe, ice from Mont Blanc has notably preserved traces of natural climate variations over the past millennium.

While the temperature has increased by 1 °C in France over the past century (compared to 0.6°C worldwide), it has risen 1°C to 3°C at 1,800 meters in the Alps in the winter. Similarly, on-site measurements taken from a drilling hole on the Col du Dôme at 4,300 meters in the French Alps indicate an increase in the temperature on the surface of the glacier of almost 1.5°C between 1994 and 2005. We know that the temperature of the ice on the Col du Dôme is closely linked to that of the air and that future warming will only accelerate this glacial warming.

The Andes

The Andean barrier is geographically unique and helps us establish a link between the tropical region - a driver for climate - and high-altitude regions where glaciers records covering longer periods (800,000 years in Antarctica) already exist.

The rise in temperature related to global warming will be sharper in the tropical regions at an altitude of around 6,000 meters reaching +5°C by the year 2100 in some scenarios. This is particularly true in the Andes, where the abrupt retreat of the glaciers since 1960 has led to the disappearance of many of them, such as the Chacaltaya glacier in Bolivia. This glacial retreat is extremely worrying in terms of water resources for the local populations.