Satellite data from 1962 to 2004 indicates that more than 1,000 Himalayan glaciers have retreated by around 16%. However a new study shows that in the past glaciers may have grown in response to warming, showing that responses to climate change are difficult to predict.
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NEW DELHI: A small group of Himalayan glaciers grew in size when the Earth became hotter 9,000 years ago, new research says.
The study shows that responses to climate change can sometimes be difficult to predict.
Summer Rupper, professor of geology at Brigham Young University in the United States, reports in the September issue of Quaternary Research that a small group of Himalayan glaciers grew by several kilometres 9,000 years ago.
Curiously, the growth occurred during an 'interglacial' period when central Asia was hotter by 6ºC.
Shifting weather patterns
Rupper's findings are based on a model that predicts both glacier mass and energy balance at its surface under varying regional climatic factors such as temperature, humidity, cloud cover, rainfall, and wind.
She reported that shifting weather patterns at the time caused increased precipitation and brought more clouds and winds to the area, making it cooler and providing more water to help ice formation.
Her team is now extrapolating the findings to a new project to predict future water changes in the area, which is under threat as glaciers melt because of global warming.
The report helps us better understand how a rise in temperature affects the height at which snow accumulates, commented Anil Kulkarni, coordinator of the snow and glacier project at the Space Applications Centre in Ahmedabad, India.
Carbon dioxide concentrations
However, the paradox of glaciers increasing in size - and not melting - during warmer conditions occurred under very different conditions, which would not occur today.
During the last four interglacial periods, including the period addressed in Rupper's research, that occurred in the past 350,000 years, carbon dioxide concentrations remained below 300 parts per million (ppm). Present carbon dioxide levels have exceeded 380 ppm because of global warming, Kulkarni told a South Asian media workshop on climate change in August.
Satellite data from 1962 to 2004 indicates that more than 1,000 Himalayan glaciers have retreated by around 16%, Kulkarni said.
