July 29, 2008
The very mention of Tibet brings to our minds images of protesting monks and the Dalai Lama. But Tibet is much more than this and far more important to us than just being an irritant in Indo-China relations. The Tibetan Plateau is the world’s largest store of ice – after the Arctic and the Antarctic – and like the two poles it is witnessing far reaching changes in its ecology. A recent report in scientific journal Nature has brought into focus the central role Tibet is playing in global climatic change, in general, and in India’s climate, in particular.
Like in the polar regions, ice in the Tibetan plateau is melting fast. Nearly 82 percent of its glaciers have retreated in the past half a century and 10 percent of its permafrost (permanently frozen ground – a mix of soil and ice) has degraded in past decade. The reasons for this melting are not far to seek. In summers, dust rising from deserts can go up to 10 km in the atmosphere. These dust particles both absorb and reflect sunlight – affecting the amount of radiation that reaches the plateau. The second important reason for changes in Tibetan ecology is the amount of black-carbon emissions from India and other countries in the region. When this black-carbon settles on glaciers, it darkens them, making them absorb more heat and they start melting. Chinese scientists have found that the melt season in Tibetan glaciers is beginning earlier and lasting longer.
The melting of glaciers and resulting formation of glacial lakes has increased the risk of flooding on the Northern slopes of the Himalayas. The thawing of permafrost could endanger the newly opened Qinghai-Tibet Railway line, as the ground below would subside the same way it is happening in the tundra. The most significant impact of the warming of Tibetan plateau would be on the Indian monsoon. As we know, monsoon is a result of interplay between thermal currents over the land and oceans. Warming of the plateau would lead to creation of a vast area of surface warmer than the air, thereby increasing the land-ocean pressure gradient and affecting the monsoon, the Nature report points out.
Chinese scientists – who have studied ice preserved in Tibetan glaciers as an indicator of changing climate – have concluded that warmer the plateau was, the weaker was the monsoon. An increase of 0.1 degree Centigrade was linked with a decrease of 100 millimeters in snow accumulation. Besides Indian monsoon, a warmer plateau would impact climatic changes on a global scale as well. So, it is high time that India – which has been exploring the Antarctic for the past two decades and has begun research in the Arctic recently – turns its eyes on the Third Pole as well.