365 Days of Climate Awareness 291 – Glacial Retreat in the Himalaya

The Himalaya contain 19,600 sq km/7500 sq mi of ice, third behind Antarctica and the Arctic as a region, in the form of high-altitude glaciers. NASA satellites confirm the retreat of many Himalayan glaciers, and the formation of a large number of lakes on their surface, both indicating rapid melting. Databases of ground-based and satellite data stretching back more than 50 years show glaciers throughout the mountain range in various rates of retreat. 

Glacial mass loss throughout the Himalaya, Hindu Kush and Karakoram mountains, 2003-08.

Geological mapping, using sedimentary forms to estimate earlier ice positions, shows an increase in melt rate within the last five decades ten times the average since the Little Ice Age maximum (between 1300-1600). This melt rate reflects accelerated warming in this region beyond the world average. The melting is worsened further by pools of meltwater on top of and in front of the glaciers, because liquid water is much more efficient than air at transferring heat to the ice. Since the albedo—reflectivity—of water (0.1/1) is far lower than that of ice (0.6-0.9/1), it becomes an extremely effective conductor of solar heat into the glacier.

Terminal glacial lake.

The Hindu Kush  and Karakoram mountains, to the northwest, provide water mostly through a winter snow-spring melt regime, but the Himalaya provide a combination of spring melt plus summer monsoon. Even so, the loss of ice plus rising water demand in India and Bangladesh mean a looming water shortage problem for the region. Estimates of the imminent disappearance of the Himalayan glaciers are exaggerations, but their retreat is real. Credible estimates hold that the mountain range could lose 2/3 of its glacial ice by the year 2100. In the face of rising demand, this will lead to a less stable water supply for at least 7.5% (600 million) of the world’s population.

Supraglacial lake.

Tomorrow: the Tunguska event in Russia.

Be brave, and be well.