Water, excess or shortage is bad
By: V.K. Joshi*
It is now well known that we are facing the perils of climate change. Our planet is presently in the midst of a tug of war between La Nina and El Nino. Till last year it was La Nina and what a havoc it created! The gruesome tragedy of Kedarnath is still fresh in mind. But geoscientists tell us that the mankind has been facing the wrath of the nature since times immemorial.
For example, there is a Belan River - a tributary of the Ganga River, lesser known to the common man, but a paradise for the geologists and archaeologists. Our ancestors of Paleolithic and Neolithic cultures lived there, but at two separate places in the same valley. What must be the reason for this shift? Geologists, like forensic scientists have hawk like eyes and a nose powerful enough to decipher the clues of the past floods and droughts.
M.R. Gibling of Dalhousie University, Nova Scotia, Canada, Rajiv Sinha and N.G. Roy of IIT, Kanpur, S.K. Tandon of University of Delhi and M. Jain of RisŲ National Laboratory, Radiation Research Department, Roskilde, Denmark, gathered the clues from Belan Valley and found that everything was almost frozen till about 18000 years ago, a period known as the Last Glacial Maximum (LGM). The freezing had shrunk all the rivers and howling winds carried lots of dust in their wake. The river valleys are ideal places for these wind borne sediments to be deposited. Once the atmosphere became warmer, the ice began to melt and the rivers, once again started their usual task of carrying sediments and depositing them in their flood plains during the monsoon. Thus, Belan valley has an interaction of the river borne and wind borne sediments both, say Gibling et al.
Our ancestors knew the pulse of the rivers better and avoided the flood prone areas on the banks of the rivers. That could be one reason that the first rice growing habitation developed, away from the wrath of the floods, on the southern fringe of Ganga plains under the shadow of scarps of Vindhya mountain ranges in the Belan valley. Gibling et al. state that in this area, 20 m thick alluvium was deposited by a river which was meandering through the area. This alluvium is the storehouse of the Middle Paleolithic artifacts and has been dated between 85711 to 7278 kyr BP. It naturally implies that during these 78,000 years there was a sustained river activity in the area.
Around the Middle Stone Age, the community faced the constraint of sudden change in the course of the river. As the river abandoned its course and shifted to a newer reinvigorated course later, the farming and animal herding Neolithic community developed along the new course.
In short, the change in climatic conditions led to the change of the river course and forced the more advanced Neolithic community to shift to an area where the newly developed agrarian community could thrive.
This has been happening with the man kind since long. Last year, thousands of people of Uttarakhand became climate refugees in their own land and are still living in the refugee camps, waiting to resettle. Like excess of water, the shortage is equally dreadful. Floods are fearsome killers, but the droughts are worst. Past droughts are often deciphered with the help of Phytoliths (Greek: Plant Stone). A German botanist, Struve reported them first time in 1835. Since then lots of research has been carried out on Phytoliths and they have been well classified.
Anju Saxena and Vandana Prasad, Scientists of Birbal Sahni Institute of Paleobotany, Lucknow with Prof. I.B. Singh of Centre of Advanced Studies in Geology, Lucknow University studied the phytoliths from the Lahuradewa Lake sediments (in Sant Kabirnagar district, U.P.) to reconstruct the past climate. On the basis of Phytoliths, Anju et al. found that between 10300 calibrated years before present (Cal. B.P.) and 9200 Cal. B.P. for nearly 1100 years Lahuradewa experienced a dry phase. Such droughts in the present times can be disastrous.
As said in the beginning, till last year, our planet was under the spell of El Nino, that brought excess rains in the Himalayas, leading to landslides and brought misery for the thousands. In Kedarnath area alone 122 landslides were recorded by David Petley, a Professor of Hazard Management in the Durham University, U.K. This year, the Australian climate experts have already reported that the La Nina effect has already started and the Indian Meteorological Experts expect less than average rainfall this year. Less rainfall can lead to drought. It is bad both for animal and plant life.
The floods and droughts affect the developed countries as well, but they are better prepared to deal with them. In a developing country like India, a lot needs to be done to tackle the onslaught of climate change.
Former Director Geological Survey of India, Northern Circle, Lucknow.