Leh: An Urban Heat Island

The heating up of Leh compared to Jammu, this summer, invites scientific explanation to the phenomenon that may set in an irreversible environmental imbalance in the mountain region in future. Ladakh is a cold arid region lying in the rain shadow zone during Indian Summer Monsoon (South West Indian Monsoon) and Indian winter monsoon receiving a low mean annual precipitation of 115mm at Leh with cold temperatures qualifying it as a cold-arid region of the Indian western Himalaya.

Lack of vegetation and precipitation in Ladakh, prominent features of the region, identify it as a cold desert. During June when monsoon trough moves over the Indian sub-continent and reaches the northernmost end of India, no precipitation is received in Ladakh region whereas very little precipitation is received over Ladakh (particularly Leh) when north-east monsoon retreats during October – November in post-monsoon period.

The major precipitation is received in the region during winters and pre-monsoon periods of December to March related to the Western Disturbances.

Different climate/weather datasets from Climate Research Unit (leading institution concerned with the study of natural and anthropogenic climate change at University of East Anglia, UK), National Centres for Environmental Prediction (the centre of United Nations that delivers national and global weather, water, climate and space weather guidance, forecast, warnings and analyses) and European Centre for Medium-Range Weather Forecasts (carries out projects on the re-analysis of meteorological data) have published dis-similar results on the climate change in Himalaya.

The conflicting results based on the study of datasets suggesting increase in annual temperature trends, a pre-monsoon cooling, increase in temperature during monsoon and post monsoon seasons is attributed to the vast spatial expanse Himalaya resulting heterogenous response of sub-regions to the climate change.

Nevertheless, the climate datasets show an overall significant warming trend over Leh while significant increase is shown in precipitation. The comparative analysis reveals interesting information on the climatology over Leh. A warm period from 1901-1979 is noted over Leh followed by lowering of temperature during 1979-1991, and again from 1991 onwards there is rapid increase in temperature.

The analyses of precipitation data show a low precipitation period before 1970, increasing precipitation trend from 1970-1995, and decreasing trend in the precipitation from 1995 onwards. The increasing/decreasing temperature and precipitation trend of over different time periods show an interestingly inverse relationship between temperature and precipitation over Leh. Relative warm period before 1970s experienced lower precipitation in the region whereas between 1970s and mid-1990s there is rise in the precipitation but lowering in temperature.

The rapid increase in temperature and decrease in precipitation in the recent decades of post mid-1990s over Leh is a forewarn.

The process of urbanization, a low land phenomenon, is now noticed in high mountain regions too where some regions are experiencing depopulation, others are seeing a concentration of population around market town.

The characteristics of urbanization in high mountain areas is resultant of inaccessibility, resource limitations and sensitivity to population change, a model far different from the one applicable in developed lowland areas or in a ‘Western’ setting of urbanization. The destiny of Ladakh today is largely controlled by a centralized, lowland political power, a typical example of an ‘internal periphery’ after the closure of ‘trade borders’ with Central Asia and Tibet.

As a consequence, the local economy relies largely on tourism which, as an external economy, witness fluctuations in regional and international markets. Urbanization in Leh is defined in terms of natural increase (excess births over deaths), net migration gain, and reclassification of rural areas to urban. Based on the Census of India 2001, urbanization in Leh district is at 23%, the level close to national (28%) averages. Surprisingly, the urban population of Leh grew at an average rate of 5.92% each year between 1981 and 2001, whereas the national average was at the rate of 2.95% each year.

The sizeable ‘floating’ population comprising circular migrants, tourists and security related personnel under-enumerate the urban population in Leh. Multi-temporal analyses of satellite imageries from 1969 to 2017 show a rapid demographic growth with quintupled rise in build-up area from 36ha to 196ha - construction of 9260 new buildings between 1969 and 2003, 4780 between 2003 and 2011, and 4620 between 2011 and 2017.

New settlements, primarily residential and administrative build-ups, cover a vast barren area to the east of Leh into concretised environment. High influx of domestic and foreign tourists in Leh city in recent past has further enhanced the demand for buildings that shall add to the concrete environment.

The agriculture land has also fallen prey to the expanding urbanization between 1969 and 2017 with a loss of 1% in 1969 to rising 5% in 2003 and further to 8% in 2017. In the year 1981, 12.75% of total population of Leh district lived in urban areas which rose to 24.43% in 2001 and to 34.21% in the year 2011.

Gradual rise in the atmospheric temperature of Leh (Ladakh region) coupled with urbanization has turned the city into an ‘urban heat island’ over a period. The transformation to urbanization, though of moderate level at present, may have far reaching implications on the environment of a mountain region.

The urbanization of Leh city, in future, may invite challenges related to water scarcity and pollution (water, air and solid waste). The need of the time is to deal with the situation, as early as possible, through public-private partnership arrangement.

By: Prof. R.K. Ganjoo