Hindu Kush Himalaya
Climate change in the Third Pole
The HKH
How many poles does the Earth have? You'll probably say two: the North Pole and the South Pole. And you'd be right!
But there is another location on our planet which is sometimes informally called 'The Third Pole'. Not because of its location. But because of just how much ice is stored there. In fact, this place is the third biggest store of ice on the Earth after the Arctic and Antarctic.
Welcome to Hindu Kush Himalaya (HKH)!
HKH
From the mountains of Afghanistan in the west...
To the Himalayas to the east
The HKH feeds a number of the world's major rivers, including...
The Indus, which flows down through Pakistan.
The Ganges, which flows through India.
The Brahmaputra, which eventually reaches Bangladesh.
Describe what you can see of the HKH landscape in this photo.
The HKH landscape consists of
- high mountains with snow, ice and glacier
- steep sided valleys, with very little vegetation and sandy soil
- glacial lakes with natural dams at the end made from soil.
Image by: Zoonar GmbH/Alamy
The HKH is arguably the world’s most important ‘water tower’, being the source of ten of Asia’s largest rivers as well as the largest volume of ice and snow outside of the Arctic and Antarctica.
Together these rivers support the drinking water, irrigation, energy, industry and sanitation needs of 1.3 billion people living in the mountains and downstream.
How many people live in the Indus River basin?
[The columns show the population in millions.]
How many people live in the Ganges River basin?
How many people live in the Brahmaputra River basin?
Climate change in the HKH
The HKH is very vulnerable to the impacts of climate change. Let's take a look at two of the main causes of flooding there.
Glacial Lake Outburst Flooding (GLOF)
This is what a glacial lake outburst flood looks like
Imagine being caught suddenly in this GLOF. You can see how dangerous it would be.
Let's have a look at some of the glacial lakes most at risk of flooding in the HKH.
This lake in Nepal is particularly at risk. It's located south west of Baruntse mountain, and only 13 km south of Everest (there is it in the background!)
The lake end has already broken through one dam and is now up against another one. This could fail at any time. This part of the world experiences earthquakes too, as the Indian subcontinent collides with the rest of Asia. The shaking from these earthquakes can also dislodge the dams, causing flooding.
There is a second glacial lake in a valley just upstream.
And a third glacial lake on the other side of the valley. A steep slope beside this lake means there is a risk of a landslide (which could break the dam). And there is a glacier nearby, so ice falls from it could do the same.
Landslides and ice falls can also be triggered by earthquakes.
All in all, this is a risky location.
But how do scientists assess risk in locations as inaccessible as this...???
They use remote sensing from satellites orbiting the Earth!
This is a false colour image from Sentinel 2 satellite from 22 August 2022 of that same lake system. Without having to visit the location, we can see what's happening there.
We can examine in near real time the conditions of the lake, the dam and the surrounding area to see if anything is changing.
If this lake were to flood, what is likely to happen? Again, remote sensing can help us consider that.
At first, the flood waters would be funnelled fast down this steep valley.
Further down the valley, we start to reach inhabited places. See the houses and the farmland on the valley sides here.
A bit further down the valley, we come to some more buildings and some commercial premises.
The people living in these remote upland areas are very vulnerable to GLOFs. They are very poor to begin with. The flash floods arrive very fast and, if they have no warning, they can be swept away. Even if they survive, their homes, crops and livestock can be destroyed, leaving them extremely vulnerable.
Monsoon flooding
Every year, the Indian subcontinent experiences a number of months of very intense rainfall called the monsoon. The people who settled here in fact rely on this rainfall to build up the groundwater supplies and help irrigate their fields.
However, every once in a while, the rainfall from the monsoon is much heavier than average. When this happens, too much rain falls resulting in extreme flooding and hundreds or even thousands of deaths.
If this monsoon flooding is natural, how does this relate to climate change?
A warmer world is a world with more energy in the atmosphere. And so, the rain that falls will tend to be heavier. (The UK is forecast to have more strong storms in the future as a result of climate change).
The Indian Ocean is warming faster than most oceans. The global average for oceans is that they are 0.7°C above pre-industrial temperatures. But the Indian Ocean is about 1°C above.
This means that flood events that happened every hundred years or so in the past will become much more frequent in the future. The abnormal will become normal. With tragic consequences.
The 2022 flood in Pakistan
The summer of 2022 saw some of the worst flooding ever experienced in Pakistan, with clear links to climate change.
There were two main reasons for that:
(i) The heat wave
Record breaking temperatures were reached in April and May in South Asia. Temperatures reached above 40 °C for prolonged periods in many places. On one sweltering day in May, the city of Jacobabad reached 51 °C.
Scientists believe this probably resulted in greater melting of the glaciers and some GLOFs in the HKH, sending flood water downstream.
(ii) The intense monsoon
Warmer air can hold more moisture (water vapour). With the heat in the early summer, scientists were warning that the monsoon rains would probably be heavier than normal.
Turns out, sadly, they were absolutely right with their forecast.
In Pakistan, he monsoon rains arrived earlier than usual (30 June, 2022), rain fell for longer than usual over a larger area than usual.
Twice the average precipiation fell overall in Pakistan. But the Sindh region had 5 times its annual precipitation.
The impacts of the flood
For a disaster of the scale of the 2022 flooding, remote sensing plays an important part in getting near real time information about the event. This map shows how satellite images were used to measure how big the flood was.
The proportional circles show the numbers of people affected by flooding in the different regions in Pakistan.
This is a false colour satellite image of the area around the Indus River, taken on 27 June, before the floods. Red shows the vegetated areas.
Can you see how much bigger the river is?
Let's show the these images zoomed in a bit more
Can you see how much bigger the river is?
The floods have had a devastating impact:
- 1,302 people killed (including 416 children)
- 3,554 injured
- Over 300,000 still living in temporary evacuation camps
- $10 billion worth of damage has been done to Pakistan
- 218,000 homes have been destroyed
- 3,600 km of roads destroyed
- 145 bridges destroyed
- More than 700,000 livestock have been killed
- 17,560 schools damaged or destroyed
Behind these statistics are the stories of the millions of people affected by this hazard. This blog by Iram Sammar tells some of the stories of people she knows who live in Pakistan and how they've been working to support each other in the aftermath of the floods.
What made the floods so devastating?
To answer this question, we can come back to this equation:
So the real question is what factors have increased the vulnerability of the people in Pakistan? Climate change is increasing the hazard; but the hazard is not experienced in the same way by different groups of people.
Pakistan Floods: "A Man Made Tragedy"
Further resources
China's sponge city model can reduce urban flooding
