Nav: Home

Receding glaciers in Bolivia leave communities at risk

October 20, 2016

A new study published in The Cryosphere, an European Geosciences Union journal, has found that Bolivian glaciers shrunk by 43% between 1986 and 2014, and will continue to diminish if temperatures in the region continue to increase. "On top of that, glacier recession is leaving lakes that could burst and wash away villages or infrastructure downstream," says lead-author Simon Cook, a lecturer at the Manchester Metropolitan University in the UK.

Receding glaciers also put water supply in the region at risk. Glacial meltwater is important for irrigation, drinking water and hydropower, both for mountain villages and large cities such as La Paz and El Alto. Throughout the year, the 2.3 million inhabitants of these two cities receive about 15% of their water supply from glaciers, with this percentage almost doubling during the dry season. Glacier retreat also means less water is available to supply rivers and lakes, such as southern Bolivia's Lake Poopó, which recently dried up.

The new study is one of the first to monitor recent large-scale glacier change in Bolivia, to better understand how receding glaciers could affect communities in the country. "The novelty of our study lies in the bigger picture -- measuring glacier change over all main glaciated ranges in Bolivia -- and in the identification of potentially dangerous lakes for the first time," Cook says.

The team measured glacier area change from 1986 to 2014 using satellite images from Landsat, the U.S. Geological Survey's and NASA's Earth observation programme. They found that the area of the Bolivian Andes covered by glaciers decreased from about 530 square kilometres in 1986 to only around 300 square kilometres in 2014, a reduction of 43%.

As glaciers recede, they leave behind lakes typically dammed by bedrock or glacial debris. Avalanches, rockfalls or earthquakes can breach these dams, or cause water to overflow them, resulting in catastrophic floods known as glacial lake outburst floods. The team reports that both the number and size of glacier lakes in the study region increased significantly from 1986 to 2014.

After studying glacier change, the researchers used their 2014 glacial-lake observations to identify the lakes where outburst floods could occur and present a hazard to populations. "We mapped hundreds of lakes," Cook explains. "Some lakes are very small and pose little risk. Others are very large, but there's little or no possibility that they would drain catastrophically. Others are both large enough to create a big flood, and sit beneath steep slopes or steep glaciers, and could be dangerous."

They identified 25 glacial lakes across the Bolivian Andes as potentially dangerous to communities and infrastructure, as they could result in very damaging floods. If the smallest of these 25 lakes was to drain completely, it would yield a flood with a peak discharge of 600 cubic metres per second. The largest could result in a discharge of over 125,000 cubic metres of water, about 50 times the volume of an Olympic swimming pool, in a second.

While measuring glacier area change was a relatively simple task, Cook says "identifying which lakes are dangerous is the million dollar question" as there are various factors to take into account.

"We considered that a lake was dangerous if there were settlements or infrastructure down-valley from the lake, and if the slopes and glaciers around the lake were very steep, meaning that they could shed ice or snow or rock into the lake, which would cause it to overtop and generate a flood - a bit like jumping into a swimming pool, but on a much bigger scale!"

Such catastrophic floods have occurred in the region in the past. Dirk Hoffmann, a researcher at the Bolivian Mountain Institute and co-author in The Cryosphere study, recently documented a glacial lake outburst flood in the Apolobamba region that happened in 2009 and killed farm animals, destroyed cultivated fields and washed away a road that left a village isolated for months. "As those locations are very remote and far away from the cities, authorities at national level and the wider public are often not even aware of the new dangers that mountain dwellers are facing due to the impacts of climate change, and no appropriate measures are being taken," Hoffmann says.

Cook says these events could be under-reported, suggesting the risk of such floods in the Bolivian Andes has been overlooked. "We heard of other [glacier lake outburst flood] events from villagers when we visited the Apolobamba region in 2015, but there is no mention of these in publications or papers, possibly because many of these communities are relatively remote." Hoffmann adds: "A nation-wide risk assessment of potentially dangerous glacial lakes would be of great interest to local communities in glacier watersheds."

In the study, the team also estimated that glacier area will be severely reduced by the end of the century, to about a tenth of the 1986 values. This would put communities even more at risk from water scarcity, Cook says. "We predicted in our study that most glaciers will be gone or much diminished by the end of the century - so where will the water come from in the dry season? Big cities like La Paz are partially dependent on meltwater from glaciers. But little is known about potential water resource stress in more remote areas. More work needs to be done on this issue."

The team hope the study raises awareness about the rapid glacier loss in Bolivia, how it could change in the future, and how it could affect water supply and cause glacial lake outburst floods. "Ultimately, I hope that our results will be useful to people in Bolivia - governments, agencies, people living in rural areas and cities," Cook concludes.
-end-
Please mention the name of the publication (The Cryosphere) if reporting on this story and, if reporting online, include a link to the paper or to the journal website.

European Geosciences Union

Related Climate Change Articles:

The black forest and climate change
Silver and Douglas firs could replace Norway spruce in the long run due to their greater resistance to droughts.
For some US counties, climate change will be particularly costly
A highly granular assessment of the impacts of climate change on the US economy suggests that each 1°Celsius increase in temperature will cost 1.2 percent of the country's gross domestic product, on average.
Climate change label leads to climate science acceptance
A new Cornell University study finds that labels matter when it comes to acceptance of climate science.
Was that climate change?
A new four-step 'framework' aims to test the contribution of climate change to record-setting extreme weather events.
It's more than just climate change
Accurately modeling climate change and interactive human factors -- including inequality, consumption, and population -- is essential for the effective science-based policies and measures needed to benefit and sustain current and future generations.
Climate change scientists should think more about sex
Climate change can have a different impact on male and female fish, shellfish and other marine animals, with widespread implications for the future of marine life and the production of seafood.
Climate change prompts Alaska fish to change breeding behavior
A new University of Washington study finds that one of Alaska's most abundant freshwater fish species is altering its breeding patterns in response to climate change, which could impact the ecology of northern lakes that already acutely feel the effects of a changing climate.
Uncertainties related to climate engineering limit its use in curbing climate change
Climate engineering refers to the systematic, large-scale modification of the environment using various climate intervention techniques.
Public holds polarized views about climate change and trust in climate scientists
There are gaping divisions in Americans' views across every dimension of the climate debate, including causes and cures for climate change and trust in climate scientists and their research, according to a new Pew Research Center survey.
The psychology behind climate change denial
In a new thesis in psychology, Kirsti Jylhä at Uppsala University has studied the psychology behind climate change denial.

Related Climate Change Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Climate Crisis
There's no greater threat to humanity than climate change. What can we do to stop the worst consequences? This hour, TED speakers explore how we can save our planet and whether we can do it in time. Guests include climate activist Greta Thunberg, chemical engineer Jennifer Wilcox, research scientist Sean Davis, food innovator Bruce Friedrich, and psychologist Per Espen Stoknes.
Now Playing: Science for the People

#527 Honey I CRISPR'd the Kids
This week we're coming to you from Awesome Con in Washington, D.C. There, host Bethany Brookshire led a panel of three amazing guests to talk about the promise and perils of CRISPR, and what happens now that CRISPR babies have (maybe?) been born. Featuring science writer Tina Saey, molecular biologist Anne Simon, and bioethicist Alan Regenberg. A Nobel Prize winner argues banning CRISPR babies won’t work Geneticists push for a 5-year global ban on gene-edited babies A CRISPR spin-off causes unintended typos in DNA News of the first gene-edited babies ignited a firestorm The researcher who created CRISPR twins defends...