3-9 June 2016 #811

When melting mountains shake

Already at risk from global warming, last year’s earthquake amplified existing hazards in the Himalaya
Kunda Dixit

Sharad Joshi/ ICIMOD
KEEPING WATCH: Most of ICIMOD's monitoring stations in Langtang were destroyed or damaged by last year's earthquake. Some, like these weather stations on Yala Glacier have been rebuilt to collect data on wind speed, temperature, solar radiation and glacial surface height changes.

After the earthquakes last year, even as reports of death and destruction were coming in from remote villages, scientists worried if the jolts had weakened glacial lakes in the Himalaya formed by global warming melting the ice and snow.

An international effort immediately got underway to inspect rivers for landslide damming and assess damage to the terminal moraines of glacial lakes. The results showed that although extensive, landslides were much less serious than anticipated, and that the tremors had not increased the risk of glacial lake outburst floods (GLOFs).

“The absence of any large GLOFs following the earthquake and aftershocks was very fortunate,” concludes a recent report by the Kathmandu-based International Centre for Integrated Mountain Development (ICIMOD). “But the relatively limited damage caused by this earthquake should not be taken as an indication that damage from a possible future large earthquake would be similarly low.”

The Nepal Himalaya is one of the most densely-populated mountain regions in the world and is already exposed to the effects of climate change like floods, landslides and avalanches. The fear is that these risks could be exacerbated by earthquakes like the ones that struck the country last year.

Of the 489 glacial lakes in Nepal and China that were studied, only nine were found to have been affected by the earthquakes. However, there were many avalanches in Central Nepal on 25 April last year, and two of them were catastrophic. As many as 300 people died when Langtang Village  was obliterated and 16 climbers were killed at Mt Everest Base Camp — both by avalanches triggered by the earthquakes.

Scientists are now trying to see if there is a link between global warming and an increased risk of avalanches and rockfalls on the mountains, especially during an earthquake. Frequent freezing and thawing, and the melting of ice that acts as cement in rock fissures, due to global warming could destabilise the mountains.

In Langtang, the earthquake set off a rockfall at 7,000 m that plunged into the glacier below, bulldozing it over a cliff and lifting 7 million cubic metres of ice and rock into the air. A blast wave that preceded the avalanche blew away the village. On Everest, a serac on the West Shoulder precariously balanced by spring melting appears to have been torn loose by the earthquake. In both areas, there had been a large accumulation of snow from heavy winter blizzards.

Under its Cryosphere Monitoring Project, ICIMOD has been studying glaciers in Langtang to measure the impact of climate change (see interview below). But as if to underline how an earthquake amplifies existing geo-hazards in the Himalaya, 80 per cent of its installations in Langtang were lost or damaged on 25 April last year. 

Using glacial monitoring, remote sensing, and even drone overflights, scientists at ICIMOD have been measuring the rate at which glaciers are melting, how fast the permafrost is thawing, if glacial lakes are expanding, and how all this impacts on the hydrology of Himalayan rivers. They were also trying to quantify how much of the ice is melting due to global warming, and how much because of soot particles called ‘black carbon’ covering the snow.

Jitendra Bajracharya/ICIMOD

A team of ICIMOD scientists this spring observed that the dust and pollution being blown up the valley in Langtang was unprecedented. “I had never seen it so extreme, it was murky, and the surface of the glacier was dirty brown,” recalls glaciologist Dorothea Stumm. Soot from crop burning in north India, unprecedented forest fires and industrial pollution covered the snow, causing it to melt faster.

Researchers want to analyse the grey particles covering the ice to find out where they come from, but need to bring the frozen samples down to Kathmandu and send them off to labs in the United States. Several previous attempts failed because airlines did not allow dry ice in cargo holds. Last month, a sample carefully packed inside thermos flasks finally made it.

“After analysing the samples we will be able to pinpoint the origin of the pollution,” says Désirée Tredichler from the University of Oslo.

The glaciers of Langtang are not just retreating, but also thinning, creating melt pools and ever-larger lakes. Scientists want to evaluate what makes certain glaciers melt faster: its direction, slope, thickness of debris above the ice or soot deposition, or global warming.

Explains glacier analyst Sharad P Joshi at ICIMOD: “If we can estimate how much of the melting is due to local pollution, that will be easier to control than global warming which is more difficult to address.”

One glacier at a time

Pic: Sharad Joshi/ICIMOD

For Sonam Futi Sherpa (pic) the 2015 earthquake was a wake-up call. As a glaciologist, she was immediately alerted to rumours from her hometown of Khumjung that the Imja Tso glacial lake was about to burst.

Soon, with inspections and remote-sensing data Sherpa and others were able to dispel the rumours, and provide assurance that the moraine dam on this lake and others in central Nepal were intact and there was no danger.

“At that moment it occurred to me how urgent the problem of glacial lakes is, and how people’s lives are at risk,” said Sherpa who is working as a Research Associate Glaciologist in ICIMOD studying the impact of global warming on Himalayan glaciers, and how the melting ice is causing lakes there to grow dangerously big.

For Sherpa, one of the few Nepali scientists who lives in the area being studied, the impact of climate change is glaringly evident. What for visitors may look like a scenic panorama, is for Sherpa full of signs of accelerated meltdown in the mountains.

“There is more to glaciers than just ice, in addition to its importance for water availability it is also an indicator of climate change,” said Sherpa, who is studying changes in the 'mass balance' of glaciers in the Everest region. She is also conducting a field survey to study how fast the ice and snow are melting on Yala Glacier on Langtang, and assisting in a study of permafrost in the area.

“Even though people are aware of the changes, they do not completely understand the reasons behind them, which is why more awareness is needed,” explained Sherpa, who hopes the work of researchers like her will help Nepal adapt to the dangers of climate change.

Scientists in Nepal have to work with very little data, and they are cautious about jumping to conclusions. Sherpa says there is only eight years of data on some glaciers, and much more work needs to be done in the coming years to add to the knowledge base.

Says Sherpa: “The Alps have almost 50 years' worth of data on glaciers, we need similar long-term studies to accurately determine the exact way climate change is affecting our glaciers so we can plan for the future.”

Smriti Basnet

"Mountain people paying price for climate change"

Director David Molden of ICIMOD spoke to Nepali Times after a recent visit to the centre's climate research station in Langtang.

Jitendra Bajracharya / ICIMOD

Director David Molden of ICIMOD (pictured, above) spoke to Nepali Times after a recent visit to the centre's climate research station in Langtang.

Nepali Times: What was the most visible impact of global warming in Langtang?

David Molden: There is nothing like a field visit to really experience the dramatic signs of glacial retreat — a stark reminder of the consequences of climate change. All 105 glaciers in Langtang Valley are retreating. The side and end moraines of Lirung, Langshisha and Shalbachum glaciers clearly mark the maximum extent of the glaciers during the Little Ice Age which were much greater than what is visible today.

One striking image was the thick brown haze, which we noticed even at elevations between 4,000 to 5,000 m. The ICIMOD research team had never seen such intense haze at high elevations. This was probably a result of increasing air pollution in the region, plus numerous forest fires we have recently experienced.

What does ICIMOD research show about how serious this problem is in the Himalaya and Tibetan Plateau?

Our work so far has shown that Himalayan glaciers are highly sensitive to ongoing and future climate change, and we have measured continuous glacial retreat since the start of ICIMOD’s glacier monitoring program. Except for the Karakorum in Pakistan where some of the glaciers are actually advancing, glaciers are in retreat across the Hindu Kush-Himalaya and Tibetan Plateau.

While glacial retreat is a spectacular indicator of global changes, ICIMOD’s focus is on the impact of these changes in terms of livelihoods, ecosystem services and the environment. Research is directed toward understanding associated changes in the amount of downstream water availability for agriculture and hydropower. Also, since glacial retreat can lead to the formation of lakes retained by fragile moraine dams, part of our work consists of monitoring the formation and stability of outburst-prone lakes and the hazards of glacial lake outburst floods.

Could glacial retreat just be part of a natural cycle after the last ice age?

Decades of climate change study have conclusively found that human emissions of greenhouse gases from burning fossil fuels and biomass are by far the strongest driver of current climate change. These greenhouse gases trap heat in the atmosphere and alter the Earth’s energy balance. As a result, the increased temperatures have resulted in greater melt rates, higher snowlines, and glacial retreat throughout most of the Himalaya. While glacial retreat may have started at the end of the Little Ice Age, it is incorrect to suggest that the current retreat is only due to what you call natural cycles.

J Shea
BIG THAW: The lateral moraines of the Langshisha Glacier in Langtang National Park shows how much the glacier has retreated and shrunk.

It seems too late to mitigate climate change, do you agree that we should focus on just adaptation?

Mitigation actions taken now will reduce the amount of future warming, which can in turn prevent us from surpassing any dangerous tipping points while slowing down the effects of climate change on ecosystems. Keeping temperature levels below 1.5 degrees Celsius can slow the long-term rate of glacial loss, reduce the risk of hazards, and prevent cascading effects on the water and food systems that sustain us. Unfortunately, even if warming was stopped today, most glaciers would continue to retreat as they have been pushed out of balance by the rapid warming of the 20th century. In other words, the warming that is already in the pipeline, as it were, will only result in further glacier and snowpack losses.

The 1.5 °C target put forward at the last Intergovernmental Panel on Climate Change meeting in Paris is a good start, but requires global commitment and lifestyle changes, particularly amongst high-emission nations. One issue for mountain people is that their contribution to greenhouse gas emissions is marginal compared to more developed areas in the world. Yet, mountain ecosystems and people are extremely vulnerable to climate change and will have to pay the price. At the same time, there is a need to develop adaptation strategies and approaches for more vulnerable areas in our region.

How is ICIMOD helping?

First, ICIMOD is developing a deeper understanding of how climate change is taking place in the region, and what the potential impact is on social and ecological systems. This is particularly important for mountain areas which, despite being climate change hot spots, are sparse in data and scientific study compared to the rest of the world. Second, we work with communities, practitioners and governments to develop solutions through knowledge sharing. We are piloting climate-smart agricultural solutions for mountain communities to build resilience. Our approach is based on the critical need for knowledge sharing of the tremendous amount of innovation already taking place in the mountains. Finally, we interact with the global community to get the message of the mountains out, and tell how mountains are impacted, and that support is needed for mitigation and adaptation efforts.

Read also:

Climactic change, Editorial

Mountain people paying

Getting rid of soot, Helena Molin Valdes and Arnico Panday

Dirty snow is melting our mountains faster, Bhrikuti Rai

Back to black, Bhrikuti Rai