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Monday, April 12, 2010

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Nights getting warmer in India, says study

Amit Bhattacharya | TNN

New Delhi: In an ominous sign of climate change hitting home, India has seen accelerated warming in the past few decades and the temperature-rise pattern is now increasingly in line with global warming trends. The most up-to-date study of temperatures in India, from 1901 to 2007, has found that while it’s getting warmer across regions and seasons, night temperatures have been rising significantly in almost all parts of the country.
The rise in night temperatures— at a rate of 0.2 degrees Celsius per decade since 1970, according to the study — could have poten
tially adverse impact on yields of cereal crops like rice. The paper also finds that warming has been highest in post-monsoon and winter months (October to February), another trend that could impact agricultural output.
“Until the late 1980s, minimum (or night) temperatures were trendless in India while maximum temperatures were rising. India was an odd dot in the global map as most regions worldwide were seeing a rise in night temperatures in sync with growing levels of greenhouse gases (GHCs). Our analysis shows the global trend has caught up with India,” said K Krishna Kumar, senior scientist and programme manager at Indian
Institute of Tropical Meteorology, Pune, and one of the authors.
In other words, regional factors seem to
be getting overridden by warming caused by greenhouse gases. For instance, the cooling trend in much of north India seen in the 1950s and 60s has been reversed, possibly because the effect of aerosols in the air can no longer compensate for greenhouse gas warming.
The study — Surface air temperature variability over India during 1901-2007 and its association with ENSO— by IITM scientists D R Kothawale and A A Munot besides Kumar, is a comprehensive analysis of temperature data gathered from 388 weather stations in the country and has been accepted for publication in the international Climate Research journal.

Mercury touches a record 9-year high in city
Hyderabad was sizzling hot on Sunday with the day-time temperature touching a record 42.4 degrees, the highest-ever in the last nine years. The Met department’s forecast shows that similar temperature will prevail over the next two days. Owing to the blistering heat, most of the denizens did not dare to venture out and the roads wore a deserted look. P2
Himalayas warming up more rapidly
New Delhi: The rising night temperatures in almost all parts of the country is a major cause for worry. “Minimum temperatures have a link with rice fertility. At higher than normal night temperatures, rice grains aren’t properly filled up, leading to a drop in yield,’’ says Jagdish K Ladha, principal scientist in the India chapter of International Rice Research Institute,
During 1901 to 2007, the all-India mean, maximum and minimum annual temperatures rose at the rate of 0.51, 0.71 and 0.27 degrees Celsius per 100 years, respectively.
However, post 1970, the rise has been sharper with mean and minimum temperatures both increasing at the rate of 0.2 degrees per decade, faster than the maximum temperature which rose by 0.17 degrees.
Among regions, the hardest hit seems to be the western Himalayas encompassing portions of Jammu and Kashmir, Himachal Pradesh and Uttarakhand. Here the mean temperature rise in the last century was 0.86 degrees while, more recently, temperatures have been going up by as much as 0.46 degrees per decade. The rapid warming of the region would have obvious fallouts on glacier melts.

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