Melting Glaciers- Himalayas

What do glaciers melting in the Himalayas have to do with the Indian Ocean? How could something happening on land be connected to the sea? There is in fact a relationship:

Warming temperatures over Eurasia have caused the snow caps over the Himalayas to shrink. This decrease in snow cover has led to a change in the land-ocean thermal gradient which favors stronger summer monsoon winds in the Indian Ocean. The strengthening of these winds has enhanced upwelling (the process where nutrient rich water from the deep is brought to the surface) in ocean. Consequently, the amount of phytoplankton off of the coasts of Somalia and Oman has greatly increased. (see Prasad & Bigelow related websites and Goes, et al (2005) Science 308, 545-7. DOI 10.1126/science.1106610 for more information)

Current research finds the seasonal spring melting of snow cover over much of Eurasia is faster and more intense than before (personal communication). The Himalayan glaciers are the second largest body of ice in the world, covering 17% (3 million hectares) of the mountain area. Unfortunately, the Himalayan glaciers are retreating faster than any other glaciers (IPCC (2007) Climate Change 2007: Impacts, Adaptation and Vulnerability). The image below shows the approximate recession of the Gangotri glacier- one of the largest glaciers in the Himalayans. From 1780 to 2001 this glacier retreated almost 2 km. 

(image from: NASA Earth Observatory- Jesse Allen)

Scientists monitor glaciers and ice caps because they "are key indicators and unique demonstration objects of global climate change" (WGMS. 2007. Glacier Mass Balance Bulletin No 9.). One way of monitoring is to measure the net mass balance of a glacier. The mass balance is the difference between the accumulation and ablation (melting and evaporation) of a glacier. The World Glacier Monitoring Service has been collecting information on two Himalayan glaciers. According to the mass balance data (below) the Chhota Shigri and Hamtah glaciers have an overall mass balance loss for the last three years measured.

Chhota Shigri     -1227 mm; +144 mm; -1413 mm

Hamtah     -1857 mm; -1856mm; -1391 mm

(Data from 2003/04; 2004/05; and 2005/06* respectively.) *preliminary data

A Call for Data and Cooperation

Compared to other glaciers around the world, there is a lack of information on the impact of global warming on the Himalayan glaciers. Described as a "a blind spot, a big scientific question mark" scientists are working to correct this gap. Over 70 international climate scientists met in April 2008 to begin the task of mapping glacial retreat in the Himalayas. This task will not be easy, either scientifically or politically (see article for more information). This collaboration, along with the current research on the affect of the melting Himalayan glaciers on the productivity of the Arabian Sea, will help us further understand the impact of climate change.

Social Impacts

Millions of people in Pakistan, Nepal, Bhutan, India & Bangladesh rely on the glacial melt waters from the Himalayan glaciers. A decline in glacier mass balance can mean less water available for rivers. It is a worry that the receding glacier trend could lead to the Ganga, Indus, Brahmaputra and other rivers in northern India becoming seasonal rivers (IPCC 2007). If these major rivers are dry during the summer months irrigation, water and food supplies will be affected.

(Himilayan Glaciers map from Zemp. 2007. Glaciers and Ice Caps)

Glacial lakes are formed by melt water, and many in the Himilayas are full. Scientists and politicians are concerned that these 'brimming' lakes may overflow (outburst) and cause devastating floods (see Zemp, 2007. Glaciers and Ice Caps in Global Outlook for Ice and Snow for more information).