East and South Asia Are the Largest Sources of Black Carbon Blanketing the Tibetan Plateau

A recent study conducted by researchers at the Chinese Academy of Sciences and published in the journal Science of the Total Environment suggests that black carbon and dust play a crucial role in the melting of Tibetan Plateau glaciers—and the researchers think they know the sources of that troublesome sediment.

“We believe that black carbon, dust, and other light-absorbing impurities must be important factors in accelerating … ice melting worldwide,” Yang Li, a coauthor of the study, told GlacierHub. And, according to the study, East and South Asia are the largest sources of black carbon emissions that are transported to the Tibetan Plateau.

Black carbon, also called soot, is a byproduct of the partial combustion of organic matter and fossil fuels.

Susan Kaspari is an associate professor at Central Washington University and worked previously with Shichang Kang, another one of the study’s authors. “When you see emissions coming off the back of a truck that’s really black, you’re seeing the black carbon,” Kaspari told GlacierHub.

Along with fossil fuels, an important source of black carbon is the burning of biofuels, such as wood or animal waste, she added.

“[Black carbon] doesn’t stay in the atmosphere a really long time,” Kaspari said. “Usually it will stay in the atmosphere on the scale of a few days to at the most, maybe two weeks.”

Gravity and precipitation eventually pull the black carbon back to earth. And that’s where the trouble comes in for glaciers.

Scientists describe black carbon, along with dust, as a light-absorbing particle, meaning that due to its dark color it absorbs more energy from the sun compared to other light-colored materials—especially the typically bright-colored surfaces of glaciers. When black carbon settles on snow and ice, “It absorbs more energy from the sun, and then that warms the snowpack or ice, and leads to accelerated melt,” Kaspari said.

Kaspari and Kang, among others, published a study in 2011 that detailed how black carbon concentrations in the Tibetan Plateau have increased dramatically. “We documented a three-fold increase from preindustrial to industrial periods, starting around the 1970s, relative to, prior to that period of time,” Kaspari said.

Various anthropogenic activities contributed to this increase, including the Kuwait oil fires set by Iraqi forces during the 1991 Gulf War.

Li’s new study focused on the Laohugou Basin on the northern slope of the western Qilian Mountains, which lie on the Tibetan Plateau. These mountains lost 20.9 percent of their glacial area—about 22 cubic kilometers of ice—in the past 50 years, according to a study conducted last year.

The accumulation zone of the glacier studied by Li and his coauthors (Source: Yang Li)

Li and his co-researchers sampled the ice, snow, and nearby topsoil of the Laohugou Basin glacier during the summer and winter of 2016 and measured concentrations of black carbon and dust. To determine the effect of the black carbon and dust on the amount of energy absorbed by the glacier, they used SNICAR, a model for determining the albedo of snow and ice surface.

They found large spaciotemporal variability in the concentrations of black carbon and dust. Still, they concluded that the concentrations of black carbon and dust on the glacier were “comparable to or higher than” concentrations on most other Third Pole glaciers. The concentrations, though, were lower than those of some select glaciers of the Tibetan Plateau, specifically, including the Baishui No. 1 and Xiao Dongkemadi glaciers, which indicated, according to the study, “discrepancies in the deposition, enrichment, and re-exposure of [black carbon] over the Tibetan Plateau.”

Li and his coauthors found, however, that dust plays a more important role than black carbon in accelerating melting.

The researchers walk on a glacier in the northeastern Tibetan Plateau (Source: Yang Li).

Susan Kaspari found a similar result in her 2014 study that measured black carbon and dust on the glacier ice and snow of Solukhumbu, Nepal.

“Let’s say you had a hundred parts per billion black carbon, which would be certainly enough black carbon to cause a change in how much energy is being absorbed,” she said. “If you put that on a snow pack that was quite clean, that black carbon could have a really large impact.”

“If you took that same amount of black carbon and it was deposited upon a snow pack that already had a lot of dust,” she added, “the efficacy, or how effective that black carbon would be in absorbing energy, would be a lot less because the dust is already absorbing some of that solar radiation that could otherwise be absorbed by the black carbon.”

The Tibetan Plateau is a region that is “naturally dusty already,” said Kaspari, who added that the rising temperatures brought about by climate change exacerbate the situation. “As the glaciers are retreating,” she said, “you’re exposing more and more area that used to be covered with glacier that has a lot of dust.”

And that dust, she added, gets blown onto glaciers.

A shot of the Amphulaptsa Pass, Nepal, taken during a 2009 expedition that resulted in Kaspari’s 2014 study. The dark layers are a combination of black carbon and dust. (Source: Jesse Cunningham)

Li and his coauthors found local topsoil to be a likely source of not only the glacier’s dust, but also its black carbon. Urban activities, such as automobile exhaust and industrial pollution, release black carbon that pollutes the soil, according to the study.

To reduce the amount of black carbon released into the environment, Kaspari suggested more efficient combustion methods, more efficient engines, and the elimination of coal-fired power plants.

Natural sources of black carbon, such as wildfires, are more difficult to mitigate. And there’s no feasible way to remove black carbon that’s already settled across the surface of the world’s glaciers.

Li told GlacierHub that the results of his study do not speak to the possible concentrations of black carbon in other glaciated regions of the Tibetan Plateau. “The concentrations of black carbon and dust in the Tibetan Plateau glaciers must vary broadly, because of the spatiotemporal variability in wet, dry, and post depositional conditions,” he said.

Still, along with other studies that research black carbon concentrations in other glaciers of the Tibetan Plateau, the work of Li and his coauthors adds to our evidence that human activity accelerates the melting of glaciers in Tibet and worldwide.

Read More on GlacierHub:

Dispatch From the Cryosphere: Amid the Glaciers of Antarctica and Chile

South Asian Perspectives on News of Rapid Himalayan Glacier Melt

Ancient Humans of Glaciated Western China Consumed High-Potency Cannabis

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Farmers and Glaciers in Northwest China

A farmer in arid Gansu (Source: Mike Moss/Creative Commons).

Extending across the provinces of Inner Mongolia, Qinghai, and Gansu, the Heihe River Basin is the second largest inland river basin in China. With a core drainage area of 130,000 km2, it is home to 121 million people, and roughly 74 million of them practice farming or animal husbandry. In recent years, water demand has rapidly increased, while water availability has decreased due to glacier retreat and groundwater depletion. As a preliminary step to combat this looming crisis, a team of Chinese researchers set out to assess whether local farmers and herders were aware of glacial change and, if so, what their attitudes were toward state and local response strategies. The results, published last month in Theoretical and Applied Climatology, offer an intriguing look at the way local knowledge and state media intersect in rural China.

Guofeng Zhu, a professor of geography and environmental science at Northwest Normal University and the paper’s lead author, spoke with GlacierHub in Mandarin about the stakes of this research for farmers in the region. “Alongside population growth and climate change in recent years, the pressures on the Heihe River Basin’s ecological system have become increasingly severe. Over 70 percent of the water used for agricultural irrigation comes from the river. The question of whether farmers can efficiently adapt is of grave importance to sustainable development in the region,” Zhu said.

Researchers interview a local farmer (Source: Guofeng Zhu/Northwest Normal University).

To carry out the study, the researchers conducted informal interviews in five villages. The villages were selected according to their location along the river, with upstream, midstream and downstream villages all represented. Individual villagers were selected to be interviewed so as to provide a diverse sample size across socio-economic, educational, and occupational values. The team asked open-ended questions and also distributed a multiple-choice survey. The researchers surveyed residents about their impressions of glacier change and used data from the China Meteorological Data Sharing Service Network to assess if residents’ perceptions were accurate.

Runoff from the Qilian Mountains (Source: feelings3allen/Creative Commons).

The glacial data itself paints an unsettling picture: from 1970 to 2012, the total glacier area in China’s northwest shrank by 10 to 14 percent. This, when coupled with population growth and reductions in cultivable land per capita, does not bode well for agriculture intensive areas in arid regions, such as the Hexi Corridor, which feeds nearly the entire population of Gansu Province. The farmers living in this fragile ecosystem are faced with annual droughts that in some years can exact a heavy toll on crop yields and animal abundance. Stemming primarily from changes to the permafrost active layer of the Qilian Mountains, the meltwater that accounts for 15 percent of total runoff of this life-sustaining river is in jeopardy.

Rivers sustain agriculture in this arid region (Source: Dan Lundberg/Creative Commons).

In an interview with GlacierHub, Dahe Qin, a glaciologist at the Chinese Academy of Sciences and an author of the paper, emphasized that the story of the Heihe River Basin resounds throughout the region. “The situation of Heihe is the same as that of the other river basins of the Hexi Corridor. Global warming, as well as degradation to glaciers and the cryosphere, is having a profound impact on the oasis regions, impacting the livelihoods of millions,” he said.

The farmers and herders interviewed seem to be acutely aware of the situation. Of respondents, 82.1 percent indicated that glacier retreat was a fact. Unsurprisingly, those living upstream near the glaciers themselves were most cognizant of this fact, having observed firsthand their retreat. Their perceptions of glacier retreat were also the most highly correlated with scientific observations. Education level was another strong predictor of whether farmers were aware of glacier retreat.

A farmer living in the midstream area is interviewed (Source: Guofeng Zhu/Northwest Normal University).

Gender, ethnicity and age had no impact on awareness of glacier retreat. 85.6 percent of farmers reported that they had heard about glacial change from television. However, simply being a farmer who watches television does not mean that one will become concerned with glacier retreat. The team interviewed farmers living in a nearby river basin who had a much lower reliance on glacier runoff and found that farmers there were less concerned about glacier change than those living in the Heihe River Basin. This finding suggests that concern for glacier change is associated with the degree of reliance on glacier runoff for livelihood.

While 90 percent of those polled believed that global warming is the primary cause of glacier reduction, roughly 30 percent of respondents did not believe that waste burning and car exhaust were factors. This attention to global, large-scale factors and the comparative lack of concern with local impact surfaced in other interesting ways. Respondents located the causes of air pollution in other, more industrial regions, and believed that changes to glaciers were the result of complex, trans-regional forces.

A herder living in the upstream area is interviewed (Source: Guofeng Zhu/Creative Commons).

Accordingly, the burden of mollifying the impact of climate change was overwhelmingly seen to be the task of governments and transnational organizations: the U.N. (56.4 percent), central government (52.7 percent), and polluting enterprises (47.8 percent) were most responsible in the eyes of respondents, whereas just 21.3 percent believed that the local government was responsible for ecological restoration and management. Because most farmers did not believe they were responsible for causing glacial changes, only 11.1 percent responded that individuals or households should bear the burden of resolving the problem. The authors point to the role of the media in shaping these views, with many responses being impacted by news of the recent Paris Climate Agreement.

According to the authors, although outside expert knowledge is often inaccessible within these communities, it nonetheless plays a significant role in shaping local livelihoods. Farmers feel powerless before the hegemony of scientific knowledge: they are ever more uncertain of traditional knowledge and thus increasingly incapable of making important decisions for their own future. Zhu emphasized that farmers need to be encouraged to hold on to traditional knowledge and practices. “Our survey showed that farmers commonly view traditional herding and farming livelihoods as backward, and they aspire to urban life. That they psychologically reject farming and herding and are unfamiliar with traditional practices will weaken efforts at curbing climate change,” he said. By understanding farmers’ perceptions of glacier change, policymakers are better equipped to help them adapt to deleterious changes in their environment.

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Photo Friday: The Qilian Mountains

Located at the border of Qinghai Province and Gansu Province in China, the Qilian Mountains are the outlier of the Kunlun Mountains. Since the range is at the south of Hexi Corridor (the historic route from eastern China to other countries in Asia), it is also known as “Nanshan.”There are notable mountains in the mountain chain, including the Grand Glacier, Torey Mountains, Shulenan Mountains, and the Danghenan Mountains. The Shulenan Mountains, for example, sweep down to Qinghai Province and spread for 350 kilometers. The average height of the mountain tops is about 5000 meters. The middle of Shulenan Mountains is also the highest area of Qilian Mountains with three mountain tops higher than 5500 meters. At these high elevations, there are well-developed glaciers in the area including eight major glaciers.
Snow covers the mountain tops all year long and livestock herds graze in the well-watered valleys. Learn more about Qilian mountains here and view GlacierHub’s collection of images.

Qilian (source: Great Han / Flickr)
The Qilian Mountains in China (source: Great Han/Flickr).

 

Mount Qilian in Spring (source: Kid Chen / Flickr).
The Qilian Mountains in spring (source: Kid Chen/Flickr).

 

Mount Qilian in Summer (source: Kid Chen / Flickr).
The Qilian Mountains in summer (source: Kid Chen/Flickr).

 

Mount Qilian in fall (source: Xiwu).
The Qilian Mountains in fall (source: Xiwu).

 

Mountain Qilian in winter (sourece: Nick Song / Flickr).
The Qilian Mountains in winter (sourece: Nick Song/Flickr).

 

Shule River near Qilian Mountains (source: Binglan).
The Shule River near the Qilian Mountains (source: Binglan).

 

Startrack at Zhuoer County near Qilian Mountains (source: Zongseshijue).
Startrack at Zhuoer County near the Qilian Mountains (source: Zongseshijue).

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