The Jamapa Glacier retreat is climate change in action, and an extinction affecting rivers, rural communities, industries and marine ecosystems.
At 9am on the final day of May 2025, 70-year-old mountaineer Hilario Álvarez stopped at the edge of Mexico’s last glacier. And he listened. There it was, at an altitude of 5,300 metres: the soft crackling of melting ice. He squinted to watch the drops of water, sliding down stalactites hanging beneath the ice sheet before disappearing into the porous soil of Citlaltépetl, the highest mountain in Mexico.
It is from this ice on Citlaltépetl – also known as the Pico de Orizaba volcano – that a river springs. Across hundreds of kilometres, it touches the lives of millions of people before flowing into the Gulf of Mexico. That May, Álvarez inspected a cavity that had formed between the ice and the earth, large enough for an adult to crawl inside. “Last year, there was a little more [ice] surface area,” he says. “Today, there is less and it is thinner.”
What is clear is that the Jamapa Glacier has reached the point of no return. A 2024 National Autonomous University of Mexico (UNAM) study, poetically entitled Announcement of an approaching death, compared past projections for the glacier’s evolution with the current reality. It concluded that, by the end of this decade, the climatic conditions necessary for Jamapa to continue functioning as a glacier would only occur at altitudes similar to Citlaltépetl’s peak.
The mid-point of these requisite climatic conditions for any glacier is called the equilibrium line. Above the line, the glacier accumulates more ice than is lost through melting; below the line, the opposite is true. As Jamapa’s equilibrium line continues to rise, there will be changes that force a reconsideration of whether or not it is still technically a glacier. That is according to Guillermo Ontiveros, the study’s lead researcher. “When do we say that a glacier ceases to exist? There is still no consensus,” he tells Dialogue Earth.
What does seem inevitable, according to Ontiveros, is that Jamapa will fragment into two ice bodies, one high and one low. That division could happen at any moment, and “could already be interpreted as the death of the glacier”.
Over his lifetime, Álvarez has seen all but one of the 14 glaciers that once existed on this mountain disappear. That morning, the sounds beneath the ice felt like another farewell.
“Perhaps we will become extinct together.”
Signs of climate change
During that same mid-2025 ascent, Álvarez noticed something he had never experienced since his first climb of Pico de Orizaba in December 1968, when he was only 13. He felt “warm rain” falling on the glacier. It left the ice washed and shiny, exposed directly to the sun’s rays.
A 2024 study documenting the glacier’s accelerated retreat says its surface area was 0.46 sq km in 2019. By 2024, it had shrunk to 0.37 sq km, and the crevasse under the ice at its edges had deepened. Importantly, the air temperature at the bottom of the ice body and within its accumulation zone had also risen steadily, the study notes.
As he descended, Álvarez followed the path of the meltwater. The weather behaved “like never before”, he says. There were blizzards and sudden changes. At 5,000 m, it began to rain, with lightning, in a place where it once only snowed.
Experts say this is a sign that the zero isotherm – the invisible line above which precipitation usually falls as snow – has shifted upwards. “Fifty years ago, it didn’t rain at 4,000 m. Now it rains up to 5,600 m,” says Álvarez.
Downpours like the one he experienced change everything: they cause landslides, erode the mountain and alter its morphology. They leave behind moraines – marks on rocks that reveal the presence of glaciers that have since disappeared.
Rain, once rare at these heights, is part of the glacier’s final climate. Meanwhile, its meltwater flows along an underground river towards the Gulf of Mexico.
Human impact
Once it leaves the mountain, the Jamapa enters forests of Mexican mountain pine (Pinus hartwegii). According to two local sources who did not want to be identified over safety concerns, illegal logging and timber trafficking groups operate here. Some of these groups even stop those who climb the volcano and charge a “right of way” fee.
Mountaineers and expedition members who spend the night in the Piedra Grande lodge, located on the north side of the volcano at an altitude of 4,200 m, hear vehicles passing along clandestine trails all night. One expert with decades of experience in the area, who also did not want to be named, says there are at least 30 such routes in the 20,000 hectares that make up the Pico de Orizaba National Park’s protected area. Logs are transported through here to cities in the two states that divide the mountain, Puebla and Veracruz.
Further down, the river reaches settlements in the municipality of La Perla, such as Vaquería and Nuevo Jacal. According to official data recorded in 2020, more than 55% of La Perla’s population live in extreme poverty and almost 40% live in moderate poverty.
The Pico de Orizaba National Park’s director Armando Fuentes tells Dialogue Earth there are 24 water committees in the area, made up of residents participating in reforestation and land care. He acknowledges that illegal logging remains a serious problem. The park’s former director, Luis Álvarez, says many farming families make ends meet by facilitating passage of this timber.
Mexico’s National Forestry Commission (Conafor) has established forest loss as a factor that directly contributes to global heating: the carbon that would have been absorbed by felled trees becomes atmospheric. This heating melts glaciers.
However, Mexico’s environment ministry (Semarnat) says deforestation is the national park’s biggest problem, and that it is being compounded by the water running down the slopes and elevated sections of the mountain, causing severe impacts for the flora, fauna and soil. Landslides, Semarnat says, are the expression of the direct relationship between glacier melt and damage to the surrounding forest.
One of these landslides formed during Hilario Álvarez’s descent. A loud crackling from the earth announced the fall of rocks, stones, mud and water.
Signs from the sea
After its course has run more than 300 km, beyond the mountain forests, Jamapa’s meltwater joins the Cotaxtla, one of four great rivers that originate in the Pico de Orizaba National Park. It then flows through regions of fruit crops, sugar cane and extensive livestock farming. “For more than 500 years, there has been a very strong link between human communities and this river,” Jordi Vera, a researcher specialising in water consumption in the region, tells Dialogue Earth.
On its way to the sea, the river supplies water to more than half a million people across at least 34 municipalities. It also passes by large industrial operations that extract groundwater, explains Vera.
The researcher predicts that the lower basin areas “will have to adapt” to the river’s new state, that of a seasonal flow that is dependent on the rain. “People are already very concerned, because it is their most immediate source and they will no longer have water by gravity,” Vera continues. “They will have to pump it from nearby streams. Other strategies are being discussed, such as adjusting consumption and reusing water.”
This is reinforced in Announcement of an approching death, which states that the glacier’s extinction “will affect the availability of water supply” in the Jamapa River Basin.
Finally, the Jamapa flows into the Gulf of Mexico at the edge of its coral reef system. The linear distance between Citlaltépetl and this point is 110 km, but the stream of water that began as meltwater to become a torrent of sediment, nutrients and energy, feeding coral reefs and sustaining rich marine biodiversity, has been on a winding 368 km journey.
As Leonardo Ortiz, a biologist at the University of Veracruz, tells Dialogue Earth: “The glacier and the reefs have been connected for about 10,000 years.” In 2019, Ortiz led a team that discovered 23 new reefs on the central coast of Veracruz.
This team also participated in a citizen lawsuit that reached Mexico’s supreme court. Its historic ruling in February 2022 ordered a halt to the expansion of the port of Veracruz, due to its environmental impact. The case set key precedents and is considered “a turning point” for environmental law in Mexico according to the lawyer who led the 10-year litigation, Xavier Martínez. He describes to Dialogue Earth how, for the first time, the court used the “principle of prevention” and “revoked all permits and ordered a holistic and comprehensive evaluation”. The mega-project was deemed environmentally damaging, therefore infringing the human right to a healthy environment.
Today, these reefs are facing the disappearance of Jamapa, which will reduce the river’s nutrient supply. “It’s as if we were using the state of the reef and the state of the glacier as indicators of how the system is functioning,” says Ortiz. “It’s a symptom that tells you: this is happening in the glacier. But if it’s happening in the glacier, it’s happening even more intensely everywhere else.”
It is difficult to predict just what follows from the absence of the glacier. But what can be said, Ortiz notes, is that the disappearance of the glacier will affect the ecological niche of the reefs – their conditions for existence and reproduction.
Amid wind, rain and thunder, Hilario Álvarez was lucky to complete his 2025 descent from the glacier safely: “There was a lot of very strong lightning close by.”
He knew then that his body was no longer what it once was – the mountain had exacted a heavier toll than it did when he first climbed it as a boy. But with three decades of high-difficulty ascents behind him, Álvarez says the “unpredictable and beautiful” Citlaltépetl will likely summon him again.
Whether the Jamapa Glacier will still be there is less certain.
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