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Extremes of Hot and Cold Weather in India
Dash, S.K. and Mamgain, A. 2011. Changes in the frequency of different categories of temperature extremes in India. Journal of Applied Meteorology and Climatology 50: 1842-1858.

The authors write that "in the context of climate change and its impact on sectors like agriculture and health, it is important to examine the changes in the characteristics of temperature extremes of different intensities and duration."

What was done
In this particular study, Dash and Mamgain used an India Meteorological Department gridded dataset spanning 37 years (1969-2005), which they say they "examined in detail to identify changes in the number of warm days and nights, cold days and nights, and warm-spell duration index, cold-spell duration index, and short warm/cold spells of 3-5 and 1-2 days/nights for the entire country, as well as for its seven different homogeneous regions."

What was learned
The two researchers state that their results indicate "a significant decrease in the frequency of occurrence of cold nights in the winter over India and its seven homogeneous regions in the north except in the western Himalaya," while noting that southern regions show a drastic decrease in the frequency of cold nights relative to the period 1969-75, and reporting that "a significant increasing trend in the number of warm days in summer is noticed only in the interior peninsula." Summing things up in their concluding paragraph, therefore, they say their overall results indicate that "the decreasing trends in the frequency of cold nights are more significant and prevalent than the increasing trends in warm days in India."

What it means
In light of the fact that cold kills far more people than heat does, nearly everywhere in the world - see Health Effects (Temperature - Hot vs. Cold Weather) in our Subject Index - Dash and Mamgain's findings bode well, indeed, for the people of India, especially since the warming in summer is fairly minimal and should have little to no effect on agriculture.

Reviewed 18 January 2012