the wet Chennai and .. Earth's warmest year (2015) since 1880, says NASA

In olden days, if not sweater-wearing, muffler-wearing Madrasis could be spotted on roads of Chennai in December. Dec is the coldest period in Chennai, which is otherwise hot all the time ~ some may jump to say that it is already hot now and the summer could turn out to be far worse.  The oft repeated cliché is ‘this year it is much hotter than ever before !’.  The state of Tamil Nadu is dependent on North East monsoon and major % of rain is received in this season.  It would rain heavily in the months of Oct and Dec [Tamil month of Aippasi]  

In Nov 2015, there were rains and Deepvali was dampened by incessant rains which flooded some parts of the city.  The worst was to come later.  On Dec  1, 2015, freak weather conditions began and soon it was maximum downpour on a single day to swamp Chennai with the heaviest rainfall in a century. Many Chennaities lost their belongings and properties. Many areas were badly affected.  Individuals and business establishments were affected and in respect of the former – the losses were mostly uninsured and hence unrecoverable.  The World Meteorological Organisation has been producing regular updates on the scale of this year’s El Niño.  It is claimed that in El-Nino years, surface water temperatures in the Pacific Ocean rise between 0.5 to 1 C, causing warm air to rise and the colder, moisture-laden air that brings monsoon rain to India is pulled away from the mainland. During India's winter, when rainfall--governed by a separate weather system-- generally tends to occur in northern Andhra Pradesh and Tamil Nadu, the El Nino generally whets cyclones in the Bay of Bengal and brings some rain to the Orissa coast, West Bengal, parts of Andhra and Tamil Nadu.

This year, the El Nino has been extremely strong--the most in over 18 years--and coupled with unusually-cold sea-surface waters near the Tamil Nadu and Kerala coast, has gravitated extra gusts towards Chennai, says  Chief Meteorologist of  Skymet Weather, a private weather forecasting agency. "Normally, rains that would have gone on upwards towards Andhra Pradesh are now turning south towards Tamil Nadu," he added.  Other experts say that this explanation is plausible but not well-established because researchers spend far more time analysing the effects of El-Nino on monsoon rather than the winter rains, also known as the North-East monsoon.

El Niño is the warm phase of the El Niño Southern Oscillation (commonly called ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific.  El Niño is accompanied by high air pressure in the western Pacific and low air pressure in the eastern Pacific. Developing countries dependent upon agriculture and fishing, particularly those bordering the Pacific Ocean, are the most affected.

Miles away, the United Kingdom was in the middle of a massive flooding crisis. For the fourth time in a decade, large parts of Northern England were underwater following high levels of rain that caused riverbanks to burst on Boxing Day.  For Londoners, the images of the devastation in Lancashire and Yorkshire can seem very distant - it's easy to forget that London is built on the banks of a massive, tidal river.

For much of its history, London has been plagued by floods. In 1928, a combination of melting snow, a high tide, and a storm surge caused the Thames river to burst its banks, devastating central London. Iconic landmarks including the Houses of Parliament, The Tate Gallery, and the Tower of London were surrounded by water.

If you thought that the devastating wet spell has changed the climate – you are wrong.  The year 2015,  was the Earth's warmest since record-keeping began in 1880, the U.S. National Oceanic and Atmospheric Administration and NASA said Wednesday. It's been clear for quite some time that 2015 would steal the distinction of the hottest year from 2014, with 10 out of the 12 months last year being the warmest respective months on record -- and those records go back 136 years.

While it wasn't necessarily a surprise that 2015 finished in first place, its margin of victory was startling -- it lapped the field, with the average temperature across the entire planet 1.62˚F (0.90˚C) above the 20th century average, more than 20% higher than the previous highest departure from average. This was aided by a December that looked and felt more like a March or April for much of the Northern Hemisphere, where traditional winter holidays had weather that was neither traditional nor winter-like.

In fact, December became the first month to ever reach 2 degrees Fahrenheit above normal for the globe. In the United States, December was both the warmest and the wettest on record -- no other month has ever held both distinctions for the country. It is somewhat ironic that this news comes out of Washington on a day the city prepares for what could be one of the biggest snowstorms in its history -- but big snows can occur even in the warmest years.

“The whole system is warming up, relentlessly,” said Gerald A. Meehl, a scientist at the National Center for Atmospheric Research in Boulder, Colo. It will take a few more years to know for certain, but the back-to-back records of 2014 and 2015 may have put the world back onto a trajectory of rapid global warming, after a period of relatively slow warming dating to the last powerful El Niño, in 1998.

With regards – S.Sampathkumar

21^st Jan 2016.