Global warming, local factors behind a warmer winter

With temperatures being recorded above normal levels in several parts of north India, the weathermen held global warming as one of the major reasons for a milder winter this season.

Apart from global warming, local atmospheric conditions are also among the causes for a warmer winter.

The India Meteorological Department (IMD) has made a forecast of above normal winter temperatures overall, but a milder winter in north India, the core cold wave zone of the country.

A milder winter will also mean damage to crops, especially wheat, a phenomenon that was observed in the last season.

"Global warming is one of the major reasons behind this phenomenon. However, the year also depends on year to year phenomenon," said S Pai, a Long Range Forecast scientist with the IMD.

M Rajeevan, Secretary, the Ministry of Earth Sciences, also cited global warming as a major reason for a milder winter.

IMD has said that 2016 has been one of the hottest years since 1901.

Pai, however, said that several other local factors have impacted temperatures in northern India.

"Cyclone (Vardah) has brought a lot of moisture, especially in central India, which has impacted the temperature. Then there is a Western Disturbance (WD) that is expected from December 19. So, temperatures rise a bit before that. However, the WD is also likely to bring snow and rain in Jammu and Kashmir and Himachal Pradesh and not the complete northern belt," Pai said.

Rajeevan said that although global warming is now becoming a worldwide phenomenon, factors like El Nino and La Nina also have effect on temperatures.

"Sea Surface Temperature (SST) in Indian Ocean is 0.5 to 0.6 degree higher and this also has effect on the winter. Although La Nina (a phenomenon associated with cooling of Pacific waters) is at its nascent stage, this also has had an impact on winter. A full blown La Nina would have meant a colder winter," Rajeevan said.

El Nino, which is associated with heating of Pacific Ocean waters, was one of the reasons for a warm winter last year and hot summer this year.

Jatin Singh, CEO of Skymet, a private weather forecasting agency, said that winters have become late and less intense in the northern hemisphere.

"The prolong cooling goes on even after winter months. But let's hope that this does not bring rain in March and April, the way it happened in 2014 and there was a significant damage to crops. A warmer winter will affect crops like wheat, potatoes, mustard. These crops need cold temperatures," Singh said.