Explainer: What are tropical glaciers and why are they an indicator for climate change?

By 2026, some of the world’s few remaining tropical glaciers could be gone, climate scientists are warning.

Indonesia’s national geophysics agency has found that the “Eternity Glaciers” in the Jayawijaya mountains of the country’s Papua province could melt completely by 2026 or before due to rising temperatures, The Guardian reports. This could have serious implications for the regional ecosystem and sea levels.

The words “glacier” and “tropics” seem incongruous at first glance. But, as in colder climes, tropical glaciers occur in the high mountain ranges in the tropics, where the thermometer drops low enough to turn rain into snow.

There are only a few areas left globally, and they have shrunk significantly over the last few decades thanks to increasing temperatures. They can now only be found in very few places, mainly the Himalayas, the Andes, some of Africa’s highest elevations and Eastern Indonesia.

But according to Donaldi Permana, coordinator for climate research at Indonesia’s Meteorological, Climatological and Geophysical Agency, most of these tropical glaciers are in retreat as a result of global warming and climate change.

“Tropical glacial melting is very sensitive to climate change,” he told the World Economic Forum. “There is nothing to protect them against rises in temperature where they are located.”

In the Papua province of Indonesia, the Eternity Glaciers have shrunk by three-quarters in depth between 2010 and 2021 and their total area dropped from 2.4 square kilometres in 2000 to 0.23 square kilometres – less than a tenth of their original size.

Despite Jayawijaya’s peaks standing close to 5,000 metres tall and catching nearly 300 days of rain a year, rising temperatures mean that rain no longer turns into snow and the glaciers melt.

Although the trend is well-known, scientists like Permana are now warning that a combination of global warming and the Earth’s weather system moving into a hotter phase could spell the end for the Eternity Glaciers. It’s a phenomenon that affects other tropical glaciers, too, and their melting rate is increasing rapidly.

“When I was in school, we learnt that they were called Eternity Glaciers because they have been there forever,” says Permana. “From our regular monitoring, we now see that it’s unlikely that the glaciers will survive.”

He added: “The glaciers in Papua are at a lower elevation than the other tropical glaciers. Based on our observations, we could see them go first – and the others may follow.”

In recent years, temperatures have been held in check by the cooling qualities of La Niña, a weather phenomenon in the central and eastern tropical Pacific that affects temperatures across the globe. However, the world is now entering an El Niño period, which warms ocean temperatures and sets global temperatures rising. The summer of 2023 was the Earth’s hottest on record, and July 2023 was declared as the hottest month on the planet for 120,000 years, attributed to both climate change and the arrival of El Niño.

Glaciers are highly susceptible to climatic changes and considered visible indicators of global warming. In the tropics, an intensive dry season could deal the last blow to the Eternity Glaciers and their counterparts across the world.

“The temperature increase is just the first trigger for melting,” explains Permana. “As more and more ice disappears, a wider area of rock will be exposed and this darker area will absorb more radiation, which would have previously been reflected by ice and snow. So that’s why the glacier is not just melting from the top but also from the bottom.”

The glacier’s disappearance not only threatens the livelihoods of the local community but also their lives as a result of flooding.

“While this is not a problem in Papua – one of the wettest areas in the world – people in the Andes, for example, depend on fresh water from the glaciers during the dry season,” says Permana. “Without the glaciers, they will have to figure out where to get their freshwater from to survive,”

Further melting could also contribute to a rise in sea levels, which is already well documented, not least for the polar ice caps.

Following new documentation from the British Antarctic Survey this year, the secretary general of the United Nations' World Meteorological Organization, Professor Petteri Taalas, told Sky News that the world had lost its battle against glacial melting and rising sea levels across the globe. He also suggested that changing temperatures could be a constant for thousands of years given the high levels of carbon dioxide already in the atmosphere.

Indonesia faces a unique challenge, as it not only has a high share of coal in its energy mix but is also the world's top exporter of coal. However, the country has set ambitious targets to move towards net-zero emissions by 2060. The International Energy Agency forecasts that, by 2030, exports of critical minerals needed for many clean energy technologies, could outperform even its largest-ever export revenues from coal.

According to the World Economic Forum’s Global Risk Report 2023, failure to mitigate climate change, natural disasters, extreme weather and large-scale environmental damage are perceived by experts to be some of the biggest risks of the next 10 years. It calls for reinforced collective action to divert the world from this path.

Donaldi Permana’s quotes have been edited for length and clarity.