Himalayan Glaciers Melting 65% Faster | What Changed?

Himalayan glaciers are undergoing processes of change faster than they are being perceived by many. Scientific measurement reveals that the loss of glacier mass in the Hindu Kush Himalaya has accelerated by 65% between 2010 and 2019, compared with a period between 2000 and
2009.

But what does 65% faster actually mean?

That does not imply that all glaciers have been receding at the same pace throughout the Himalayas. Instead, it is a significant speedup in glacier mass loss rate for the region. Mass loss
averaged 0.17 meters water equivalent per year between 2000 and 2009 and rose to 0.28 meters per year between 2010 and 2019.

This shift is important because the Himalayan glaciers are by no means lifeless scenery. They hold water, provide river flow, affect mountain ecosystems and contribute to communities
beyond the high mountains.

The impacts are increasingly evident as glaciers shrink and thin, ice-covered lakes enlarge, river
levels rise, and hazards like glacier lake outburst floods become more likely, as temperatures
soar.

Introduction to Himalayan Glacier Melt

 
The Himalayas are the place where there is a substantial amount of snow and ice outside the
polar regions. The region is home to over 54,000 glaciers and is a source of water to major river
systems in Asia, along with the broader Hindu Kush Himalaya area.

Such glaciers are like natural reservoirs.
At high elevations, snow and ice form, stay frozen for extended durations and slowly drip into
rivers. This process is beneficial for water availability for ecosystems, agriculture, hydropower,
drinking water and other uses.

But things are shifting.

Climate change is leading to a net loss of glacier mass in many places due to warming and a
decrease in snowfall. In parallel, the pattern of snowfalls is shifting, the snow cover is
decreasing, and the freezing level is rising.
This combination makes the melting of Himalayan glaciers one of the most important changes
in the environment in the region. The issue isn't just the shrinkage of glaciers.
What is of greater concern is what occurs when a water reservoir containing frozen water that
has been releasing water gradually for centuries starts to lose ice at a more rapid rate.

What Does 65% Faster Glacier Loss Mean? 

The 65% is based on the rate of glacier mass loss in the Hindu Kush Himalaya.
The glaciers of the region lost about 0.17 meters of water equivalent per year on average
between 2000 and 2009. This loss has risen to about 0.28 meters water equivalent per year
between 2010 and 2019.

This is approximately a 65% rise.
“Water equivalent” is significant because it is used to report how much ice and snow has been
lost as water.
Thus, the headline "Himalayan glaciers melting 65% faster" should be read in the context of:
Between these two decades, the rate of mass loss increased by 65% for the Himalayan glaciers.
This does not imply that all glaciers have had the same 65% rise.

The glaciers react differently according to:
 Elevation
 Temperature
 Snowfall
 Rainfall
 Glacier size
 Glacier slope
 Debris cover
 Orientation
 Local geography
 Ice thickness
 Availability of meltwater

Some glaciers are moving back quickly, others more slowly. However, the general trend in the
region was clear, glacier mass loss is increasing.

Why Are Himalayan Glaciers Melting Faster? 

Temperature is a key factor.
As air temperature increases, there is increased surface melting from snow and ice. Warmer
weather also may lead to a change in precipitation from snow to rain, with fewer fresh snow
accumulation opportunities to replenish the ice.

This gives rise to a glacier mass loss.
Glaciers are increasing in mass when snowfall and accumulation rate are greater than their loss
of ice and melting.
It will gain mass if the rate of ice accumulation is greater than the rate of ice loss from melting,
sublimation and calving.
This balance is tilting in favour of loss due to climate change.

Rising Temperatures 

The Hindu Kush Himalaya (HKH) has warmed considerably over the past decades. ICIMOD
projects a mean temperature rise of about 0.28°C per decade in the region from 1951 to 2020.

Many glaciers are near the freezing point, and so relatively small temperature changes can be
significant at high elevations.

A slight rise or fall may alter the properties of precipitation from rain to snow and help or hinder
surface ice from melting.

Less Snow Cover

Snow is not just a temporary covering of a mountain.
Fresh snow has a high reflectivity of incoming sunlight and is protective of the underlying ice.

If the snow melts earlier, a darker surface on the glacier is left behind. These surfaces absorb
more solar energy which leads to greater melting.

ICIMOD has also seen a reduction in the days of snow cover in the Hindu Kush Himalaya.

Longer Melting Seasons

A longer melting period may result from the glaciers' earlier warming and later cooling.

Glaciers can have a longer negative mass balance period than if the ice were just lost during the
brief warm period.

Gradual losses over many years have resulted in significant changes.

Changing Precipitation

More snowfalls at glacier elevations do not necessarily occur with a warmer atmosphere.
Precipitation is becoming more rain than snow in some locations.

This results in a two-fold effect:

 More ice is lost through melting.
 Less new snow is available to replace it.

What Changed in the Himalayas?

isn'just that glaciers are melting. What it is, is that the losses have been growing rapidly.

A series of interrelated changes have been observed by scientists:
 More rapid glacier mass loss
 Increasing glacier retreat
 Rising freezing levels
 Declining snow cover
 Changing precipitation patterns
 Expansion of glacial lakes
 Thinning glacier ice
 Increasing exposure of unstable mountain slopes
 Greater risk from cryosphere-related hazards

These changes feed off each other in a vicious circle. As glaciers recede, they may form an
outcrop of previously buried rock. Additional meltwater may fill in basins and behind moraine
dams. A growing glacial lake can become a potential source of sudden flooding. Meanwhile,

warming can cause the frozen ground to melt and can cause changes in the stability of mountain
slopes. This indicates that the environmental issue of the Himalayan glacier melt is not a
standalone issue. Can produce a domino effect throughout the mountain system.

How Himalayan Glacier Melt Affects Nepal 

Nepal has a close linkage with the cryosphere in the Himalayas.
There are thousands of glaciers, snowfields and glacial lakes in the country's mountains.
Meltwater supports river systems that provide for communities, agriculture, ecosystems, tourism
and hydropower.

Glaciers are changing in Nepal, and this can result in both an excess and a deficit of water, and at
different times.

In the short term, if there is more melting, then more water can be added to rivers.

That sounds beneficial.

That's not a permanent boost though.

As glaciers shrink, they will have less natural water storage capacity for the future.

Eventually, during some dry periods, the amount of melted water available can become less.

This creates a difficult transition:

Additional melting will reduce stored ice tomorrow.
Glacier change has implications for both disaster risk and long-term water security for Nepal.

Glacier Lake Outburst Floods and Rising Risk

A common hazard that is visible with the melting of Himalayan glaciers is a glacier lake outburst
flood (GLOF).

A GLOF is a sudden release of water from or from near a glacial lake.

A natural barrier such as a moraine, ice or something else can hold back the lake. If this barrier
breaks, massive amounts of water can be quickly swept downstream.

Melting of glaciers does not always trigger the event.
A lake can break out and flow if a rock avalanche, landslide, ice avalanche, earthquake, heavy
rain, or sudden change in the water level occurs.
That is why it is not sufficient to just count glacial lakes.

Scientists need to know more about:
 Lake size
 Lake depth
 Dam stability
 Glacier movement
 Surrounding slopes
 Rockfall potential
 Downstream settlements
 River channel characteristics

There are now over 25,000 glacial lakes in the Hindu Kush Himalaya, and increasing warming
is leading to the creation and growth of many of these lakes.

Why GLOFs Are Dangerous

A normal river flood occurs over a given time.
A GLOF can be quicker.
A sudden release of water can carry:
 Rocks
 Boulders
 Mud
 Ice
 Trees
 Sediment
 Broken infrastructure

This mix can trigger a flood, which can become a spinning roadrunner of debris, destroying
bridges, roads, houses, farmland, hydropower plants and trekking facilities.

The Thame Glacial Flood in Nepal 

The August 2024 flood event in Thame Valley, Solukhumbu, was a good example of the
complexity of the hazards in the Himalayas.

A rock avalanche above a glacial lake caused a chain reaction, according to ICIMOD study.

The avalanche hit a lake at around 4900 meters, setting up a strong displacement wave, which
resulted in water escaping from the lake. The released water then had an impact on another
glacial lake whose moraine dam then broke.

The combined output of the two lakes was an estimated 459,000 cubic meters of water.

This flow displaced debris for around 80 kilometers downstream, damaging homes, a school, a
health post, a bridge and a hydropower facility.
Luckily, there were no fatalities reported.

The Thame event is significant as it demonstrates that glacier-related disasters need not be a
linear progression of “glacier melt → increase in lake size → lake burst.”
On the contrary, several geologic and climatic conditions may occur simultaneously.
This instills greater significance in monitoring and risk assessments in the high mountain valleys
of Nepal.

How Glacier Melt Changes Himalayan Rivers

Glaciers are natural reservoirs of water. Snow and ice fall during colder times.

In warmer times, the meltwater flows into streams and rivers.
When glaciers become smaller, this natural storage capacity decreases.

Firstly, higher melting may lead to higher river discharge in some seasons.

But as the amount of stored ice declines, the long-term contribution from glaciers can eventually
decrease.

This results in peak water as the scientists would say.
Peak water is the point where glacier runoff is highest but will decrease as glacier mass loss
continues.

This poses a significant planning challenge for downstream communities.
The problem is therefore not simple:

Seasonal timing matters for:
 Farming
 Drinking water
 Hydropower
 Ecosystems
 Tourism
 Livestock
 Urban water supply

River flows may be higher at one time but water stress (or scarcity) higher at another.

What Happens to Himalayan Water Supply? 

The Hindu Kush Himalayas is also known as the “water tower of Asia”, as the snow and
glaciers feed into the big river systems of the continent.
These rivers eventually support huge populations downstream.
ICIMOD estimates that glaciers in the region are a critical water source for nearly two billion
people.

But glacier water is not the only part of the flow in the river.
Other sources include rainfall, snow melting, groundwater, etc. This implies that the impacts of
glacier retreat vary across river basins.
The seasonal availability of water is the most significant issue for Nepal.

Communities could be vulnerable to:
 Decreased dry-season glacier contribution
 Increased river flow variability
 More reliance on rain
 Increased competition for water
 Agricultural pattern change
 Increased demand for drinking-water systems

These effects can start to be seen over the course of decades and not all over at once.

Effects on Agriculture and Food Security 

Predictable water is the key to agriculture.
Climate change is happening on top of existing challenges of mountain farming systems.
Changes in glaciers and snow can also affect the flow and amount of water to downstream
regions.

Excessive water can lead to flooding and erosion.
Lack of water at critical growth stages may adversely affect agricultural production.

Climate change may also directly impact crops.
Loss of glaciers is just one aspect of a broader climate-related problem in the Himalayan
agriculture sector.

The problem is not just the melting of a glacier, far away in the mountains, it is also for the
farming communities.

Effects on Hydropower 

Nepal has huge hydropower potential, and many hydropower projects rely on the river systems
of the Himalayas.

This, therefore, may impact on the planning and operation of hydropower.
More runoffs can be opportunities, but can also be more sediment, erosion and flood.

GLOFs pose especially serious consequences, as they can release very large amounts of water
and debris in a rapid time span through a small valley.
A hydropower facility was damaged in the 2024 Thame flood, illustrating this risk.

The planning of future hydropower projects must take not only the average water flow of the
river, but also the extreme events into account.

Engineers should take into account:

 GLOFs
 Landslides
 Debris flows
 Sediment loads
 Glacier retreat
 Changing precipitation
 Extreme rainfall
 Changing seasonal discharge

Effects on Mountain Communities 

The changes near glaciers are first felt by people living nearest to the glaciers.
Water availability, slope stability, floods, landslides and damage to infrastructure can be affected
in mountain communities.
The danger is particularly high as many Himalayan villages are situated in steep river valleys.
hazard can start several kilometers upstream and get quickly downstream.
Tourism communities may also be impacted. Trekking routes may have to be altered in case of
glacier retreat or increased risk.
If glaciers retreat or hazards increase, trekking routes may need to be modified. So,
environmental changes have economic implications as well.

What Happens to Himalayan Landscapes? 

Glaciers are significant land shaping agents.
They expose rock and sediment that could have been under ice for centuries, as they retreat.
New lake sites can develop.
Existing lakes can expand.
Exposed and unstable moraines are possible.
Changes to river channels can occur when more sediment is transported downstream.
The landscape can thus evolve without the catastrophic flood.
These changes can already be seen in glacier tongues, exposed to rock, growing melt water
bodies, and changing ice formations, in places like the Everest region.

Even from a distance, the mountains appear to be forever.
Nevertheless, they are in continual flux at the glacier scale.

Are Himalayan Glaciers Going to Disappear? 

The disappearance of all the Himalayan glaciers will not be simultaneous.
Elevation, climate, geometry, precipitation, and future greenhouse-gas emissions are all
important determinants of their futures.
ICIMOD estimates that with warming of about 1.5–2°C, about 30–50% of the glacier mass
would be lost in the HKH area by 2100 from 2015.
It is not to say that the entire Himalayas will become ice free by 2100.
Big glaciers in high places might be more likely to persist. Smaller glaciers and lower-elevation
ice bodies are generally more vulnerable.
What is important is that the current trend has long term implications. The loss in mass each year
lowers the ice that remains in the mountains.

What Can Be Done? 

The primary cause of the glacier loss is global warming, which needs to be stopped.
Lowering greenhouse gas emissions is, thus, essential.
However, even if mitigation is successful, there will be glacier loss, as the climate system takes
time to react. The need for adaptation is, therefore, also vital for the Himalayan countries.

Nepal and other countries in the region can strengthen resilience through:

Better Glacier Monitoring 

Satellite imagery can be used to detect glaciers, lakes, and rapidly changing glaciers and lakes,
along with drones, automatic weather stations and remote sensing.

Early Warning Systems

Warnings to communities downstream from potentially dangerous glacial lakes must be reliable
and allow sufficient time to evacuate.

Glacial Lake Risk Assessment

Not all glacial lakes are the same.
Lakes identified as posing a risk to settlements, roads, bridges, hydropower, or trekking routes
should be identified during a risk assessment.

Safer Infrastructure

The risks of flooding and landslides must be taken into consideration for roads, settlements and
bridges in vulnerable valleys and for hydropower plants.

Local Preparedness

There is a need for people living downstream to have a practical evacuation plan, warning
system, communication network and regular disaster preparation drills.

International Climate Action

Although the glaciers are in the mountains their climate change is linked to the global emissions
of greenhouse gases. It cannot independently stop global glacier loss.

Local adaptation can reduce risk.

 
Local adaptation can reduce risk. Although, it cannot halt the loss of glaciers on a world scale on
its own.

What Does 65% Faster Really Tell Us? 

The most important message behind the 65% figure is not the number itself.

It is the direction of change or direction of the change.
The rate of mass loss of the Himalayan glaciers increased significantly in the 2010s compared to
the 2000s.

The glaciers are changing in response to a warmer climate in the following ways:
 Faster mass loss
 Glacier retreat
 Thinning ice
 Reduced snow cover
 Expanding glacial lakes
 Changing runoff
 Increasing cryosphere-related hazards

The impact of this glacier is far reaching.
A glacier might recede high in a valley and downstream impacts can be felt long after with
altered water resources, on agriculture and crop yields, on hydropower, on ecosystems, on
tourism, and on disaster risk.
From the distance, it appears as if the Himalayas have remained the same.
However, the ice has other news.