When you think about melting glaciers, South America probably isn't the first place that comes to mind. But in Bolivia, where tropical glaciers envelop the Andes Mountains, their fate looms large as climate change worsens. As a result, many rural communities at now risk from water deprivation and sudden flooding.
A new study published today in The Cryosphere, a scientific journal dedicated to the research of frozen water on Earth and other planets, found evidence to suggest that flooding from glacial lakes formed by trapped meltwater could be catastrophic for Bolivia's mountain villages. Its results underline how little we currently know about this phenomenon in Bolivia, and stress the importance of dedicating more resources to understanding climate change's effects across the globe.
The paper is among the first to measure significant glacial changes across the Andes, and its authors believe their findings could help to predict which lakes pose the greatest risk to rural communities.
"We talked to a village leader who recounted an event that his father had seen," Simon Cook, the study's lead author and a lecturer at the Manchester Metropolitan University, told me. "His father had witnessed a flood from one of these glaciers, only it wasn't documented, wasn't in any scientific paper, and wasn't reported locally. It was just one of those things that people would see."
When massive glaciers recede, several things can happen. Meltwater runoff, which provides drinking water, hydropower, and irrigation for local communities can disappear. Some 2.3 million urban residents living in La Paz and El Alto, for example, receive around 15 percent of their water from glaciers, according to the study. A 2009 New York Times profile of climate change in Bolivia speculated that El Alto, the country's second-largest city, could become "the first large urban casualty of climate change."
Another consequence of glacier melt is the formation of "proglacial lakes," which are created when water is dammed up by debris or bedrock. On their own, these lakes aren't inherently dangerous. But if displaced by a rock avalanche or landslide, they could overtake an entire village downstream. If access to roads is cut off by debris, communities can go weeks without disaster relief.
In Huaraz, Peru, a glacial lake called Palcacocha burst and flooded the city in 1941. An estimated 5,000 people were killed.
"It's a bit like dive-bombing into a swimming pool," Cook said.
Using satellite images, collected by the United States Geological Survey between 1986 and 2014, the team identified 25 lakes that could pose a risk to rural communities. Cook and his colleagues mapped "hundreds" of lakes in Bolivia. Their diagnoses were based on whether the lakes were located upstream from villages, roads, and infrastructure, and their vicinity to glaciers or mountains.
Between 1986 and 2014, Bolivian glaciers became 43 percent smaller as temperatures in the Andes Mountains increased by 0.7°C in 50 years. The country's most iconic glacier, called Chacaltaya, made headlines in 2009 after scientists discovered that 80 percent of its surface area had retreated since 1982. It was 18,000 years-old, and vanished in the relative blink of an eye, years before it was predicted to completely disappear.
The health of Bolivia's glaciers has been more or less neglected in scientific literature, according to Cook. Bolivia is one of the poorest countries in South America, and as a developing nation, is especially vulnerable to the effects of climate change. Approximately 60 percent of the country lives below the national poverty line.
"A lot of the research that's been done has focused on how big cities like La Paz—some ways away from the mountains—are going to be affected. If you're actually living up in the mountains, it's a bit of a double whammy. You're not only exposed to threat of lake outburst floods, but you're also exposed to changes in water supply," Cook added.
The researchers hope their results will be considered more broadly within Bolivia, and by NGOs working on water resource issues in developing South American nations. At the very least, Cook hopes the study can offer a wakeup call about the dangers of glacial lake flooding.
"It's a chance to put the entire jigsaw puzzle together."
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