Wednesday, October 5th, 2016

Indian cities show dramatic rise in mean temperatures: Study

Rashme Sehgal | October 5, 2016 4:24 pm Print
These findings are along expected lines because scientists at the India Meteorological Department (IMD) have made repeated warnings to both the government and the Ministry of Urban Development that India has got hotter in the last four decades
Rising Temperature
Recent findings of weather scientists are extremely alarming for India as a combined study by the Institute of Tropical Meteorology (IITM) and the World Meteorological Organisation in Geneva has revealed that Indian cities are showing marked increase in temperature.
Delhi, Jaipur, Bengaluru, Ahmedabad, Hyderabad and Kolkata have a dramatic rise in mean temperature. Coastal cities, including Mumbai and hill stations, which at one time were known to be the pride of the country, are also witnessing a dramatic increase in day and night temperatures.
These findings are along expected lines because scientists at the India Meteorological Department (IMD)  have made repeated warnings to both the government and the Ministry of Urban Development that India has got hotter in the last four decades.
Long-term data gathered from the IMD’s 103 weather stations also reinforce this trend  emphasising  a dramatic increase in temperatures from 1961 to 2010 with the last decade between 2001 and 2010 proving to be the warmest for India and also for the globe.
Dr LS Rathore, who retired recently as director general of the IMD, confirmed this trend, pointing out,’increased urbanisation is definitely contributing to his phenomenon across the country’.
Temperatures have risen in the range of 0.8 to 1 degree Celsius with an increase in the number of hot days in India.
Rising temperatures  across urban pockets are  in line with the findings of the fifth assessment report of the UN Intergovernmental Panel on Climate Change where scientists have noted that the last three decades have been the warmest since scientists started keeping records since 1850.
The reason for these rising temperatures is primarily because carbon dioxide concentrations have increased 40 per cent since pre-industrial times and these concentrates have affected both our atmosphere and resulted in heating up our oceans.
The projections of this IPCC report both mid-term (2045 to 2065) and long-term (2081 to 2100) for South Asia and specifically for India can hardly be considered favourable. The report has warned that north and west India will face an increase in temperatures while south India will face an increase in tropical nights.
Maximum temperatures during the day are expected to increase between 4 and 5 degrees C while the number of tropical nights (the number of 24-hour days above 20 degrees C) is projected to increase from between 0 to 80 days largely in south India.
Scientists at ITM  have enough evidence to show that  rising temperatures will adversely impact monsoons. So on one hand, while rainfall is expected to increase by 10 per cent from December to February and up to 50 per cent between September and November, the overall monsoon winds are likely to weaken.
‘While monsoon winds are likely to weaken,’ the report states, ‘monsoon precipitation is likely to intensify due to increasing  atmospheric moisture… Monsoon onset dates are likely to become earlier or not change much. Monsoon retreat dates are likely to be delayed, resulting in the lengthening of the monsoon season in many regions.’
The extreme heat is expected to be reflected in  an increase in extreme weather events as happened during the torrential rainfall that hit Hyderabad recently. The same phenomenon was witnessed in Uttarakhand in June 2013 and also  caused flooding of the Jhelum river in Jammu and Kashmir in 2014 that resulted in the  destruction of a large swathe of  Srinagar.
Apprehensive of the rapid rate of glacial melt, the Nepal-based International Centre for Integrated Mountain Development has warned that 54,000 glaciers in the Himalayas could create glacial lakes which would rupture their banks and destroy the surrounding infrastructure and agriculture. The bursting of the glacial lake in Kedarnath precipitated the devastation in Uttarakhand.
Rathore added, “The Minister of Urban Development needs to study the whole issue of  mushrooming of cities and migration of people into urban conglomerates in much greater detail.  We need to understand  how increasing urbanisation will handle future climate problems, especially since cities produce three-quarters of greenhouse gas emissions related to household consumption and also due to increased traffic use.”
Rashme Sehgal
The writer is a senior journalist