by Caitlin Rawling
December 14, 2023
from ABC Website

The research could change

how peri glacial environments are studied.

(File photo).

(AP: Niranjan Shrestha)

Himalayan glaciers have been rapidly melting and are predicted to continue to do so.

However a report has found the glaciers have been cooling due to cold winds going down the mountain slopes...

In a new report (Local Cooling and Drying induced by Himalayan Glaciers under Global Warming) published on Nature Geoscience, researchers have found downslope winds have been helping cool the glaciers.

Over the past few decades, Himalayan glaciers have shrunk significantly as global temperatures continue to rise.


The report states that Himalayan glaciers provide a crucial source of water to over a billion people in South Asia.


The melting of the Himalayan glaciers

 threatens the water security of over one billion people.

(AP: Rajesh Kumar Singh)



The shrinking of the glaciers has contributed to water uncertainty within region and is predicted to continue doing so throughout the 21st century.

Although the glaciers are expected to continue to melt as global temperatures 'rise', the report shows that,

Himalayan glaciers have somehow counter-intuitively been cooling and drying in recent decades...

According to the report, researchers have found enhanced downslope winds known scientifically as katabatic winds,

are behind why the glaciers have been cooling and drying...



What are Katabatic winds?

Katabatic winds are downhill winds that are generated when the surface of a mountain is cooler than the adjacent atmosphere, which creates a pressure gradient.

Himalayan glaciers rely on rain from,

  • the storms in the region in winter

  • the rain from monsoon season in the summer...

Winds from the monsoon season are drawn upwards in the daytime and are met with the katabatic winds, the study shows.



A diagram of a cloud raining onto a mountain range

with blue and purple arrows pointing down.
These diagrams show the katabatic winds

are cooling the glaciers.

(Supplied: Nature Geoscience)

The research shows the convergence between the upward monsoonal winds and the downhill winds causes the monsoonal moisture to be lifted, generating a decent amount of rain, snow, sleet or hail over the glaciers.

Increase in katabatic winds may have implications

According to the report the escalation of katabatic winds in recent decades still has consequences.

The first consequence is that daytime temperatures over the glaciers have decreased. This is because of the pumping down of cold air from higher altitudes.

The decrease in daytime temperatures has the tendency to reduce the melting of glaciers, contradicting the observed loss of glacier mass.

The second consequence of the enhanced katabatic winds is to drive the convergence line between upslope and downslope winds further down the mountain.

This means that precipitation has increased at lower elevations, but decreased at the higher elevations where glaciers are situated.

The decrease in precipitation over the glaciers has caused them to lose mass over the past few decades.




New peri glacial study model

According to the study, it shows this could be developed into,

a new type of model of how the local climate in peri glacial environments responds to global warming.

The study also suggests the warming of the atmosphere can intensify the katabatic winds, which blocks the flow of moisture from lower elevations.

This is because high altitudes contain so little moisture, which means the glaciers are dependent on the upslope flow of moisture from the low altitudes.

As the Himalayan glaciers have significantly shrunk, it is likely that they are particularly vulnerable to this effect.

The model of how peri glacial environments respond to global warming can not be used on all glaciers though.



Large chunks of ice

amongst pieces of gravel.
The Passu glacier in the Karakoram mountain

has gained mass.

(Reuters: Akhtar Soomro)

According to the research, the Karakoram mountain range has gained glacier mass over recent decades.

The glaciers in Karakoram depend on the rain, sleet or snow from the winter, meaning this particular model would not apply.

Therefore the particular model that could be developed from the study, is likely to only apply to glaciers that are dependent on the rain, sleet or snow during the summer period.