When you lose a glacier
2025/03/01 Galarraga Aiestaran, Ana - Elhuyar Zientzia Iturria: Elhuyar aldizkaria
“The message is not optimistic, because this is the reality. We're not going to start covering the glaciers with white plastic sheets like they do in the Alps. No matter which side we look at, such measures make no sense unless we continue to exploit the ski slopes for a little longer. There are no tasks.”
“The loss is irreversible. It’s not just ice; when we lose the glacier, we lose the historical record. As the layers of snow accumulate, organic traces are trapped in the ice: lichens, leaves, etc. They form a history book. When the glacier melts, all that information disappears.”
These are the words of the glaciologists Eñaut Izagirre Estibaritz and Ixeia Vidaller Gayán, respectively. They do not conceal the brutality of the situation and the extent of the loss. UNESCO has declared 2025 the International Year of Glacier Conservation, and March 21 will be International Glacier Day.
Both nominations have the same objectives. According to UNESCO, the main goal is to make people aware of the key role that glaciers, snow and ice play in the climate and hydrological cycle, along with the economic, social and environmental consequences of the changes taking place in the Earth’s cryosphere. From a scientific point of view, the aim is to share best practices and knowledge relevant to the area and to address issues related to the accelerated defrosting of glaciers and its consequences.
This is exactly what Izagirre and Vidaller are all about, focusing on the nearest glaciers: The glaciers of the Pyrenees. They form the largest group of glaciers in southern Europe and reached their maximum during the Little Ice Age. But since 1850, they are losing their surface and their thickness. In southern Europe, the glaciers of the Pyrenees are very sensitive to changes in climatic conditions, so they are of great importance as geo-indicators of climate change. In this sense, it is significant that the loss has accelerated or accelerated in recent times.
An accelerated loss
At the end of 2024, the two researchers published a study that demonstrates acceleration, together with other members in the journal Regional Environmental Change of the group Nature. Specifically, after the loss of mass in 2022 and 2023, they described the state of the glaciers in the article, confirming that these two years represent a particularly hard turning point.
Izagirre explains that in 2011, the Monte Perdido glacier was systematically investigated and then the study has been extended to the entire mountain range. In this regard, the support of technology has been essential: “Now we get much more detailed data and better resolution, and the logistics are also much easier. For example, we used to go to Monte Perdido with the laser scanner on the ground and collect the data from the witness. It was very heavy and not easy logistically. Now, thanks to drones, we have high-resolution laser scanners and orthoimages of the air and we get three-dimensional images of the entire mountain range."
“In reality, in other areas, this technology is already used, but for us it is very useful. This allows us to have topographic maps with very high resolution”, adds Vidaller. “So, if you want to know how the glaciers have evolved over a period of time, you just have to compare the images of both periods and see how they have changed over that period. In addition to these maps, we also use other methods to collect data, and from the analysis of all of them we have seen that from 2011 to 2020 the glaciers have been decreasing year after year, both in expansion and thickness. During this decade, about one meter per year was thinned. In 2022 and 2023, the thinning has been much more pronounced: the loss of thickness has tripled and, in some places, even quadrupled”, explains Izagirre.
The loss on the surface is also obvious. The study shows that the largest glaciers (covering more than 10 hectares) have decreased the most from 2020 to 2023, with an average loss of 8.3 hectares. It is more representative if we look at the percentages, since the glacier of Ossau and the glacier of Eastern Maladeta have lost more than a quarter of their surface: 30.3% and 36.6%, respectively.
Impact of climate change
The researchers have also described the climatic conditions from 2020 to 2023 in their article. “Contrary to what many people think, glaciers are not so affected by how much snow they get in winter, but by how long it lasts in summer,” explains Vidaller. “In 2022 and 2023, by the beginning of June, ice had already begun to appear, meaning there was not enough snow on the glaciers to protect them from melting. Then, in the summer, there were strong heat waves, with temperatures higher than usual and longer durations. And, even in the fall, the temperatures were quite high.”
"It should be noted that if the snow melts rapidly in the spring, everything accelerates, because the albedo effect also decreases," adds Izagirre. The reflection of the sun's rays is called the albedo effect; if the snow disappears, the Sun heats the rock at the edge of the glacier, which also causes the ice to melt, even if the air temperature is ignored.
And, according to the models, these climatic conditions (advanced springs and strong and long heat waves) will occur more and more times, Izagirre recalls. "The situation is irreversible, and although early predictions indicated that glaciers would be lost by the middle of the century, we are now seeing that it is likely to happen in a shorter period."
In addition to warming up, Vidaller points out another factor associated with climate change: Cattle of dust from the Sahara. Due to climate change, it is expected that this will also happen more often, and it has been observed that the glaciers are seriously affected: “Not only because of the albedo, because the dust obscures snow and ice, but also because of its influence on the structure.”
Interaction of factors
In fact, this is what researchers at the BC3 research centre on climate change demonstrated in a study published in the journal Annals of Glaciology in November 2023. The study, carried out in the Monte Perdido glacier, showed that the impurities present in the ice have reshaped the microstructure of the ice, changed its dynamics and accelerated the degradation of the glacier.
The focus was on a 20 cm section of an ice core from 2017, which was clearly marked by a layer of reddish-brown impurities. According to the researchers, the more particles there are, the smaller and more irregular (less rounded) ice grains appear. Numerous previous studies on polar ice indicate that this structural change facilitates the internal movement of the glacier. From this, they conclude that even in Monte Perdido, these microstructural changes can accelerate the flow of the glacier to warmer and lower areas, which would cause the ice to melt faster.
They also confirmed that the particles in the ice core of the Monte Perdido glacier were from the Sahara desert, and Vidaller recalls that in 2022 the arrival of Sahara dust cattle was also evident in the Pyrenees. Climate change is caused by more than just rising temperatures. “It’s because of the interaction of all factors,” he says.
On the other hand, there are also protective factors. Izagir gives some examples: “These are topoclimatic factors. The topography itself, whether the place is a celebrity or a laioza, whether the surface is covered with erosion or sediment, whether it stays in the wind... In these cases, during a snowfall or an avalanche, it is possible that more snow accumulates and the glacier lasts better. In the last year, for example, we have seen this: the glaciers of rugged circuses and halls of fame are the ones that have resisted the mass the best and, on the contrary, those that are in larger places, such as the glaciers of Aneto and Ossoue, have lost the most.”
However, he clarifies that even those who have maintained the situation have not maintained it because they are in balance. “I mean, it’s not because the balance between winning and losing has been zero, it’s because they’re rising to the top. And today, they are at the highest level that can last. They can’t climb higher because the sun gives them on the peaks. In other words, they stay in places where they can last and, in addition, they can’t climb any more.”
The conclusions of the researchers are clear and consistent with the theoretical predictions. “In the end, the Pyrenees are a reflection of what is to come,” warns Izagirre.
The global phenomenon
Izagirre can confirm first-hand that the melting of glaciers is not limited to the Pyrenees. In fact, it is investigating the third largest ice mass in South America, in Patagonia. “More than 90 percent of the Earth’s ice is in Antarctica and Greenland. The rest is located in the highest mountain ranges on the planet, in the sub-polar areas of the High Arctic, and on the periphery of the sub-arctic territory, and we are seeing in all of them that the melting of glaciers is accelerating in general. And the most negative balances are taking place in Patagonia,” said Izagirre.
He also explained the reason for this: “It doesn’t have as much ice as the highest mountain ranges, such as the Himalayas, Karakoram or Alaska, and it’s losing more than a meter of thickness a year. In addition, it reaches the sea, where there is not only contact with seawater, but also other dynamics that degrade the glacier: the geometry of the fjord, the landslides...”
There have been exceptions. Izagirre pointed out that some places in Karakorum, for example, are experiencing very large mass transfers in one place, and that positive balances are therefore taking place in those particular places. “But in most cases, more than 9 out of 10, they are melting and delaying.”
Some have disappeared before our eyes. According to the United Nations, among those lost in recent years are the Pizol Glacier (Switzerland, 2019), Sarenne (France, 2023), Anderson (USA, 2015), and Martial Sur (Argentina, 2018). Izagir has added tropical glaciers to the list of disappearing glaciers, some already lost and others in critical condition: From Tanzania (Kilimanjaro), Venezuela, Colombia...
What is lost
“When you lose a glacier, you lose more than ice,” says Vidaller. But he also explains what comes up: “The glaciers’ retreat reveals what we call the mother rock, the lithological substrate beneath the ice. It also shows the morphology that the glaciers produce. These are U-shaped valleys which are filled with water, either from melting ice or from rainwater. And the ibos are created. An example of this is the iboia Innominato, Aneton. In addition, we are seeing that the soil also forms very quickly. After all, the matter carried by the glacier builds up at the bottom and produces sediment. So, in two or three years, there is probably some soil with its plants, bacteria...”
But it is not only created, but also destroyed, and this is what Vidaller has been talking about: “When the ice disappears, there is a decompression effect on the rocks. Somehow, they breathe and fall and fall.”
Izagirre adds what happens to the permafrost on the wall: “He is not a permafrost in Siberia or Alaska, but a permafrost or alpine. After all, all rocks, whether granitic, metamorphic or sedimentary, have pores or fractures, and the water is frozen in the interstices. As the temperature increases, the water melts, and this change in volume causes cryoclasty or gelifration. That’s what makes the rock break and fall.”
As a result of all this, some of the traditional high mountain routes have become more dangerous than before; the normal route of Aneto, north of Monte Perdido... Undoubtedly, for mountaineers this is also a major loss.
Speaking of the human aspect, however, Vidaller has placed particular emphasis on awareness: “Some people don’t care about losing glaciers. He's also glad he won't need crampons. But I think we should take advantage of this loss to warn of climate change. In fact, it is not easy to be aware that the climate is changing because it is a long process. The loss of glaciers is occurring during our lifetime and is clear evidence for people to understand that it is a consequence of climate change.”
Even for those who answer that the fluctuations in the Earth’s temperature are cyclical, Vidaller has irrefutable evidence, as he also investigates the paleoclimate. He says it clearly: “It is true that the Earth’s climate changes cyclically, but if you look at the scale and speed at which change occurs, there has been nothing like it now in Earth’s history. For example, the last violent climate change occurred 11,700 years ago and was very rapid, one of the fastest known. This change took place between 1,000 and 1,200 years ago. This is happening on our own time scale.”
