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Our boiling destiny

, June 15, 2017, 0 Comments

destiny-climate-change-india-marketexpress-jnLast September I wrote that the troubles Syria is going through may well be due to climate change – specifically, to a decline in rainfall that has made agriculture less viable and forced people to move out of villages into towns. Unskilled young men who might have plucked oranges earlier have migrated to Aleppo and taken to looting and stealing – activities that the West has honoured with the label of terrorism but which are what workless youth indulge in in many lawless countries.

Climate change is universal; how will it affect India? India’s climate has already been changing for the worse, and it has been documented by many scientists. They have various explanations. Massimo Bollasina and his colleagues from the programme in atmospheric and oceanic sciences in Princeton, in an article in Science in 2011, attributed the drying up of India to aerosols – particles in the air. The particles are mostly soot and the ash of combustibles and ammonium sulphate, but also include condensation trails left behind by jet planes in flight. They obstruct heat absorbed by land during the day from escaping back into the atmosphere at night. This effect is increased by humidity; aerosols that rise into the air catch the humidity around them and form droplets, which increases their size and hence their obstruction of nocturnal radiation. Bollasina et al give high marks to aerosols for the weakening of the monsoon over India.

In 2014, Nature published a letter from Deepti Singh and her colleagues in the department of environment earth system science in Stanford University. They plotted precipitation (which is what climatologists call rainfall plus snowfall) in central India between 1950 and 2010, and found a distinct declining trend; it had also become more unstable. Extreme wet spells became less frequent after 1980; extreme dry spells became more frequent. Water from extreme wet spells can flow off; but there is no way the deficiency in comfort from extreme dry spells can be made up.

How did this weakening of the monsoon affect land use? This question was taken up in a report by Supantha Paul of Indian Institute of Technology, Bombay and his colleagues in Nature of August 2016. They gave a map of soil cover in 1987 (they chose to call it land use and land cover). Almost all of India was then what they call woody savannah – it was covered with shrubs that were too short and sparse to be called forest. The only large areas that were not savannah were croplands in the Gangetic valley and barren or sparsely vegetated land or shrub-covered land in Rajasthan and northern Kashmir. The northeast had some areas covered with deciduous or evergreen forest; otherwise woods were largely absent.

In the 2005 map, most of the woody savannah south of the Gangetic valley was marked as agricultural land. Not that it was not agricultural in 1987; either the scientists had changed the term or the first map was done in fallow season and the second in crop season. Evergreen forest had spread in the northeast; this was the scientists’ term for the spread of tea gardens. But the biggest change was that much of Tamil Nadu and southern Andhra Pradesh had become urban. There was similar urbanization, though on a smaller scale, northeast of Bombay and east of Ahmedabad. The leaf area index – that is, the proportion of area covered by leaves – had fallen 10-20 per cent in most of the peninsula. Precipitation had fallen all over the northeast, Gangetic plain, southern peninsula and the western ghats region. The fall in precipitation due to the change in land use was greatest in the northern peninsula, stretching from Gujarat across Madhya Pradesh to West Bengal, and along the western ghats. The shrubs in woody savannah have long lives, whereas crops are removed within months. So shrubs have deeper roots than crops; they can draw water from greater depths, and can therefore transpire more water. Hence the conversion of woody savannah to crops has reduced evapotranspiration – the release of water vapour into the air.  Evapotranspiration adds to the moisture in the air, and it comes back down to earth as rain if the humidity is high enough. So conversion from savannah to crops has been a factor in the reduction of rainfall. Rains cool land; air above cooling land flows down and out into surrounding dry, hot areas, which heat it up and then it rises. Thus, precipitation leads to winds. The frequency of low-level winds has gone down in the past three decades. The reduction in winds makes hot places hotter. The areas where temperatures have gone up most are in the western peninsula, across Gujarat, Rajasthan and Madhya Pradesh. So, the future is already upon us. Global warming was supposed to hit us some years from now; actually, it has been with us for three decades. It was supposed to be due to rising concentration of greenhouse gases in the atmosphere. Maybe it was due to aerosols. It was supposed to be global warming. What we do have is India warming; and sitting in India, it feels the same. Hitherto, governments of the world have been coming together to plan coordinated action – in the UN framework convention on climate change in Rio de Janeiro in 1992, in Kyoto in 1997, in Bali in 2007, in Copenhagen in 2009, in Cancun in 2010, in Durban in 2011, in many other attractive resorts – and failing to act together. India has been one of the main saboteurs of coordinated action; it argues that its greenhouse gas emissions till now are a small proportion of the total and that it should be allowed to continue polluting, while other countries point out that emissions are emissions – they are just as harmful whoever is responsible for them.

It is immaterial which side one takes in this conflict. The point is that India is suffering already, and even if it thinks the rest of the world is guilty, it ought to take action to help itself.

It must be in two directions. One is to economize on water and to ameliorate local shortages. Transporting water in trucks from existing lakes and ponds is an expensive solution and will get costlier as fuel becomes costly; what is necessary is getting rainwater into the ground as fast as possible and minimizing evapotranspiration. The other is to find cheaper ways of heat amelioration. Water coolers, replaced long ago by air conditioners, will make a comeback if the government lets electricity be priced at cost. Le Corbusier invented sunbreakers to keep his buildings in India cool. They were a good invention, which has been carried forward by architects across the world. Now we need another Le Corbusier, who would bring another burst of cooling inventions. He might well start with a nineteenth-century British experiment in India – residence below the ground. With luck, most Indians may be living underground half a century from now, hardly noticing the searing heat outside. To tempt them to leave their caves, the ground above should be covered with trees and bushes that would keep it cool with evapotranspiration, and whose roots would take rainwater underground before it evaporates