The Himalayas have been nicknamed the ‘third pole’ [1] as the region is home to the largest number of glaciers outside of the polar regions, but Himalayan glaciers are facing pressure from climate change.
Himalayan climate is rising faster than the Northern Hemisphere average [1], causing the large volumes of ice found in the Himalayan region to melt rapidly. A recent paper by Zheng et al. found that the risk of Glacial Lake Outburst Floods – or ‘GLOFs’- occurring in the Himalayas will increase three-fold by the end of the century. [1]
Image 1: Glacial melt water flowing through snow in Himalayas, Sharada Prasad, CS via Wikimedia Commons)
As glaciers melt, they retreat depositing large structures of debris called moraines. These moraines dam in meltwater, forming glacial lakes. Since 1990, the number and size of Himalayan glacial lakes has increased by 5.9% [1] meaning that the pressure on moraine-dams has become significant. Moraines can collapse under pressure (for example, pressure induced by a rockfall into the lake) leading to a GLOF [2,3] – in which large volumes of water are suddenly released damaging infrastructure as far as 120km away [4] and threatening vulnerable communities. [5]
Zheng et al’s research used satellite data to calculate the capacity of 6,000 glacial lakes in the Himalayas. The 6,000 lakes were chosen because they are moraine dammed and pose the highest GLOF risk (moraine dammed lakes have accounted for 46% of GLOFs since 1550).[1] Through glacial modelling at different projected levels of climate change (representative carbon pathways 2.6, 4.5 and 8.5) the research forecast how these lakes would be affected, accounting for likely triggers for a GLOF and using griddled land data to identify vulnerable infrastructures and communities. The research found that 1/3 (2,323) of the Lakes within the dataset presented a high or very high hazard, with 1/6 (1,203) severely threatening downstream communities. Furthermore, by 2050, the Brahmaputra, Ganges and Yangtze River basins would be approaching their maximum capacity due to glacial melting. More than 1.2 billion people rely on these rivers [5] and a GLOF here could have devastating consequences.
The findings of the paper are particularly concerning as the communities likely to be affected by GLOFs often have low levels of income and development and are not well equipped to manage or mitigate the GLOF hazard. In Pakistan, over 7.1 million people live in areas that are vulnerable to GLOFs. Of these, over 20% live below the poverty line [5], meaning there is significant social vulnerability. Early warning systems are in place to help evacuation, but even with this, GLOFs threaten their homes and livelihoods. The fact is, that low-income communities are the least able to protect themselves from climate risks, but the most vulnerable to them. This is an example of climate injustice – the inequal exposure of low-income communities to climate hazards. [7]
Identifying how and where GLOF risk is developing is vital to efforts to mitigate (reduce) the risk of GLOFs occurring and helps vulnerable communities adapt. At a global level, committing to lowering emissions will ‘buy time’ for the region to build resilience.
References and further reading :
[1]: Zheng, G., Allen, S.K., Bao, A., Ballesteros-Cánovas, J.A., Huss, M., Zhang, G., Li, J., Yuan, Y., Jiang, L., Yu, T. and Chen, W., 2021. Increasing risk of glacial lake outburst floods from future Third Pole deglaciation. Nature Climate Change, 11(5), pp.411-417.
[2]: Emmer, A. and Cochachin, A., 2013. The causes and mechanisms of moraine-dammed lake failures in the Cordillera Blanca, North American Cordillera, and Himalayas. AUC Geographica, 48(2), pp.5-15.
[3]: Global Environmental Fund, 2016. Averting a Himalayan tsunami | GEF. [online] Available at: https://www.thegef.org/news/averting-himalayan-tsunami [Accessed 3 Dec. 2021].
[4]: Hagg, W., Ram, S., Klaus, A., Aschauer, S., Babernits, S., Brand, D., Guggemoos, P. and Pappas, T., 2021. Hazard Assessment for a Glacier Lake Outburst Flood in the Mo Chu River Basin, Bhutan. Applied Sciences, 11(20), p.9463.
[5]: United Nations Development Programme (UNDP). 2017. Scaling up of Glacial Lake outburst flood (GLOF) risk reduction in Northern Pakistan
[6]: Ani 2010. Melting Himalayan glaciers to have varying impact on river basins. The Hindu. [online] 13 Jun. Available at: https://www.thehindu.com/sci-tech/energy-and-environment/Melting-Himalayan-glaciers-to-have-varying-impact-on-river-basins/article16245342.ece [Accessed 3 Dec. 2021].
[7]: Open Canada. (2016). Inequality Explained: 7 ways climate change and inequality are connected. [online] Available at: https://opencanada.org/inequality-explained-7-ways-climate-change-and-inequality-are-connected/.
