See this article on Global Warming "'Himalayan glaciers 1st victims of global warming'"
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'Himalayan glaciers 1st victims of global warming'
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New Delhi, March 22: Himalayan glaciers were probably the first to bear the brunt of climatic changes and began to melt during early to mid-18th century, claims a new study.
Researchers studied composite organisms developed on the loops of the moraines formed by the Chorabari glacier near the famous Kedarnath shrine in Uttarakhand to arrive at the conclusion.
A moraine is any glacially formed accumulation of soil and rock.
The study, carried out by Ravinder Kumar Chaujar of the Wadia Institute of Himalayan Geology, Dehradun, concluded that the period when the Chorabori glacier started receding from the point of its maximum advancement in this part of the Himalayas.
The study was published in Current Science.
About 2000 lichens -- composite organisms -- in the region were measured of which seven were marked for future reference. These lichens showed a growth of one mm per year.
The largest lichens on the boulders of lateral moraines of loops in the four stages of advance and retreat of the glacier were 173 mm, 155 mm, 94 mm, and 52 mm, respectively.
Lateral moraines are parallel ridges of debris deposited along the sides of the glacier.
The growth rate of lichens and time taken by it to grow on the surface after its exposure to the atmosphere, suggest that climatic changes in this part of the world started nearly 258 years ago, Chaujar said.
Chaujar claimed that the Chorabari glacier began forming during the mid-14th century, thereby kickstarting the Little Ice Age and continued advancing till around 1748 AD.
"After the peak of the Little Ice Age, recession of the glacier was followed by its three major stages of advance and retreat as indicated by the four loops of terminal and lateral moraines of the glacier," he said.
Mounting evidences now suggest that the period between 1750 AD and 1800 AD, rather than the late 19th century represented the culmination of the Little Ice Age.
In the past 400 years, the glaciers grew in size between 1600 AD and 1700 AD, as recorded in medieval documents and reached the greatest Little Ice Age extent in the 18th century, probably between 1780 AD. and 1795 AD.
"Since then, they have undergone an overall retreat punctuated by numerous advances and retreats," Chaujar said.
Lichenometric dating studies at the Eugenie, Hooker, Mueller and Tasman glaciers in Mt Cook National Park, South Alps, New Zealand reveal that the Little Ice Age was maximum during the mid-18th century, the study said.
A study in Breheimen, southern Norway found peak avalanche activity between 1685 AD and 1750 AD, the same time as the outlet glaciers were expanding to reach their Little Ice Age maximum limits.
http://www.zeenews.com/sci-tech/eco-news/2009-03-22/516980news.html