Is El Nino responsible for Increase in Temperatures? – Part 1

One of the often asked question among weather watchers Is El Nino responsible for Increase in Temperatures? Is there merit in the argument put forth often “El Nino & Global warming go hand in hand” In this study we look at a possible correlation between El Nino and temperatures across various places in India to understand if there is a clear relationship. We also take a close look on how temperature in Chennai reacts to periods of El Nino.

For this study we have taken about 8 locations across the country with focus on South India keeping in mind our objective in finding the possible impact of El Nino on Chennai temperatures. The stations chose are those that have mean temperature records from 1950 to 2015 consistently. The station data has been collected from Goddard Institute for Space Studies, NASA.

Map

In order to prevent daily maximum temperature data, which could see spikes, skewing the results the scope of this study has been restricted to the Mean Temperature data which brings out any consistent warming trend much better than individual day temperature data.  The period of study covers 1950 – 2015. Is El Nino responsible for increase in temperature? Let us find out. In the first part of the series we will look at the cities of Mumbai & Bangalore today.

ElNino_Temp_2

Going through the temperature records of Bangalore & Mumbai it is fairly clear of a possible association between El Nino and increasing mean temperatures. Both Bangalore & Mumbai has seen highest mean temperatures in  3 out of 5 months during this period in the months of January – May. While in the case of Mumbai the highest max temperature has occurred in Non El Nino years in the case of Bangalore more often than not coincided with El Nino Episodes concurrently.

Another interesting point which comes out in this data crunching is surprisingly Strong El Nino years have not resulted in higher mean temperatures for Mumbai as compared to moderate and weak El Nino years. In the case of Bangalore though the average mean temperatures during Strong El Nino years is the highest among all years. This possibly indicates a much closer coupling between El Nino and increased temperatures in the case of Bangalore while the association is not as clearly defined in the case of Mumbai.

Is there a relationship between El Nino & increase in temperatures? “Yes” in the case of Bangalore and “May Be” in the case of Mumbai.