CNN —
The climate crisis affects almost every region of the world. But perhaps one of the most visible indicators of its impact is its effect on Earth’s iconic glaciers, an important source of freshwater supplies. Glaciers have melted at a breakneck pace in recent decades, accounting for about 20% of global sea level rise since 2000.
Now researchers at the United Nations Educational, Scientific and Cultural Organization have found that glaciers in a third of the world’s most beautiful parks and protected areas will disappear by 2050 – regardless of whether global warming is slowed or not.
Among the glaciers on the brink of disappearing at World Heritage sites are those in two of the United States’ most-visited and popular parks — Yellowstone National Park, which experienced unprecedented flooding earlier this year, and Yosemite National Park.
The list also includes some of the largest and most famous glaciers in Central Asia and Europe, as well as the last remaining glaciers in Africa, namely Mount Kenya and Mount Kilimanjaro.
Glaciers at World Heritage sites shed around 58 billion tons of ice each year, UNESCO reports, which is the total amount of water used annually in France and Spain combined. And these glaciers have already contributed almost 5% to global sea level rise over the past 20 years.
The study provides the first global assessment of both the current and future scenario of glaciers in World Heritage sites, according to Tales Carvalho Resende, project manager at UNESCO’s Department of Natural Heritage and author of the report.
“This report sends a very strong message in the sense that World Heritage sites are iconic places – places that are extremely important to humanity, but especially to local communities and indigenous peoples,” Resende told CNN. “Ice loss and retreat are accelerating, so this sends an alarming message.”
Only if we limit global warming to 1.5 degrees Celsius above pre-industrial levels can we save the glaciers in the other two-thirds of these parks, scientists say — a climate goal the world is a long way from meeting, according to recent reports. The global average temperature has already risen by around 1.2 degrees since the industrial revolution.
Glaciers cover around 10% of the country and provide freshwater for households, agriculture and industry downstream. Under normal conditions, they take up to a millennium to fully form; Each year they gain mass from snow or rain and lose mass by melting in summer.
Melting glaciers might seem like a distant problem, but Resende said it’s a serious global problem that could hit communities downstream hard. He highlighted Pakistan’s deadly floods this year, which submerged nearly a third of the country. The multi-week floods were reportedly likely triggered by a combination of heavier-than-usual monsoon rains and multiple outbursts of glacial lakes due to melting that followed the recent extreme heat that engulfed the region.
“When water melts, that water will accumulate in so-called glacial lakes; and if water comes, these glacial lakes could burst,” he said. “And this outbreak can cause catastrophic flooding, which we’ve seen in Pakistan recently.”
Thomas Slater, a glaciologist at the University of Leeds in London, found that these glaciers contribute only a small part to sea-level rise compared to the amount of ice loss that the Antarctic and Greenland ice sheets could cause. Researchers like Slater have already found that these ice sheets will be the largest contributors to global sea level rise this century.
“While it is sad to hear that some of these glaciers may be lost, we should hope that reducing emissions can save most of them and avoid disrupting water supplies to millions of people worldwide living downstream,” he said Slater is not involved in the UN report, CNN said.
As the climate crisis accelerates, more water is being released from glaciers. In drought-stricken areas like the western U.S., a rise in meltwater may be a good thing, but Resende said it’s only temporary.
Once a glacier’s peak water — the maximum meltwater it contributes to the system — is reached, annual runoff decreases as the glacier shrinks to the point where it can no longer produce a water supply.
According to the report, many small glaciers in the Andes, central Europe and western Canada have either already peaked or are expected to do so in the coming years. In the Himalayas, annual glacial runoff is expected to increase sharply around 2050, before falling steadily thereafter.
If countries fail to keep global warming below 1.5 degrees or even 2 degrees, glaciers will only continue to recede, the report shows. In this future, locations would see significant glacial runoff during rainy seasons, with little to no flow to quench drier and hotter conditions.
“This is a hot topic in the research community right now – to see what the landscape will be like after the glaciers melt,” Resende said. “Unfortunately, the glaciers continue to melt because there are always delays. Because of this inertia, even if we stop or drastically reduce our emissions today, they will continue to decrease – and it is extremely important that we manage to implement adaptation measures.”
The report comes as leaders gather in Sharm el-Sheikh, Egypt, next week for the UN-brokered international climate talks, which will focus on getting countries to commit to more austerity to commit to fossil fuels that would limit global warming to 1.5 degrees. They will also discuss plans to adapt to worsening extreme weather events, such as heat waves, floods and storms.
“We really need to unite to make that 1.5 target as achievable as possible,” said Resende. “The effects could be irreversible, so this is really a promise to take urgent action.”