Current drought in Sri Lanka is not due to El Nino, but in spite of El Nino

By K.C. Somaratna Introduction

We should be thankful to Dr. Lareef Zubair and his team at the Foundation for Environment, Climate and Technology (FECT) for writing a very well-illustrated article on the ongoing drought in Sri Lanka. It starts by saying that (a) its intensity compares with the initial phase of the major drought in 2013 and (b) it shall likely not be sustained for too long. Towards the end, they say that (i) from May 2015 El Nino conditions persisted for almost a year until May, 2016 and (ii) El Nino condition was one of the contributors to suppressed rainfall until April and to the May deluges. 

When Sri Lankan climate scientists – from the most famous downwards – write to the Sri Lankan papers about a water related disaster, whether a drought or heavy precipitation, ultimately the finger will be pointed towards the El Nino or La Nina. When we check in the internet about the relationship between the particular disaster and El Nino/La Nina phenomenon, we find that the internet would predict the opposite. But we would not mind it because it was a Sri Lankan Scientist’s specific explanation and a generic statement in the internet. But this context is different.

ENSO-Rainfall relationships

Dr. Zubair along with C.F. Ropelewski wrote a technical paper to the Journal of Climate in April, 2006 under the title of ‘The strengthening relationship between ENSO and the North-East Monsoon over Sri Lanka and Southern India’. In this article they compare the relationship between EL Nino, La Nina phenomenon on one hand, precipitation during the summer monsoon in India and North East Monsoon over Sri Lanka on the other hand and the two periods 1958-1980 and 1981-2002.

Using the Heidke score for the analysis, they concluded that during both periods under consideration, El Nino conditions are associated with a tendency toward wetter conditions and La Nina conditions are associated with a tendency toward drier conditions. They further say that the relationship between Sri Lanka North East Monsoon rainfall and Nino-3 largely stayed significant at the 95% level through the last 140 year and has surpassed the 99% significant level since 1980.

On the other hand, in this current article to Daily FT Dr. Zubair and team say that La Nina conditions are likely to prevail in the coming months and even though La Nina conditions typically lead to lower rainfall from October to December, it should still lead to relief from the drought as there are wet months even with La Nina. In other words, Dr. Zubair says in this recent article that both El Nino and La Nina conditions do lead to lower rainfall contrary to what he and his colleague wrote to Journal of Climate.

What is relevant for us

Of course for us, the general reading public, what is more important is not whether Dr. Zubair has contradicted himself or not; but what the few interesting graphs presented in the article depict in respect of understanding weather patterns. In this respect the two graphs depicting variation of rainfall – month wise – during the period 2011 to September, 2016 and the variation of Weighted Anomaly Standardised Precipitation (WASP) over the period January, 2002 to September, 2016 are of great significance.

First let us consider the WASP Graph. It indicates a reasonably balanced set up till about early 2009. In early 2009, there was a very dry month and from around March 2010 wet weather persisted till about July, 2013. Then a severe drought sets in and this is the major drought in 2013 which Dr. Zubair’s team refers to at the beginning of the article. This situation ends only in about August, 2014. So there is this near 12 month drought which has persisted at a time there was no El Nino. In fact NOAA announced that El Nino has set in only on 5 March 2015. So there was no El Nino in 2013-2014 period, but a severe drought.

Coal power and droughts

When I wrote to Daily FT on 12 August on the possibility of operating our only coal power plant at 80% capacity utilisation, I worked out the relevant calculations and predicted that we would lose agricultural production, hydro energy as a result and also that the belt between Norochcholai and Sampur will become a desert. In that article, I also requested Dr. Zubair’s team to study my pronouncements and express an opinion on the same. And then comes this statement of theirs to say that the dry conditions from May 2015 to May 2016, is partly due to El Nino. 

If I were to look at this article in that respect, after reading Dr. Zubair et al’s article in Journal of Climate to the effect that El Nino is associated with increased North East Monsoons I would say, that in spite of an El Nino pronounced as one of the strongest since 1900, Sri Lanka has experienced a prolonged drought for nearly 12 months. That is a clear indication of what this coal power plant could do to Sri Lanka. The article by FECT team under reference is frightening when one looks at that map of Sri Lanka for the period July-September 2016.

When one looks at the Rainfall graph, again, one could see that in 2016, the rainfall has been at the lowest level on a number of occasions and then there is that unparalleled peak in May. So these two graphs clearly indicate that we cannot assign the droughts we experienced in both 2013 and 2015/2016 to El Nino. We firmly believe from our knowledge of climate change aspects that these droughts are the results of our attempts to operate our only coal power plant at a reasonable capacity utilisation level. If anybody has a more valid reason, please present it as we wish it very much that it is due to some other reason.

Projections for the future

Now let us look at their projections for the next few months. They say that La Nina also, like the El Nino which prevailed from May 2015 to April 2016, leads to lower rainfall from October to December, but we would have some rainfall. But our explanation will be different. When coal power plant runs at reasonable capacity, the dry conditions prevail as the atmospheric temperature goes up due to significant increase in CO2 concentration and the atmosphere retains more water vapour leading to lack of rainfall. 

This is how it was during the last few months. When the coal power plant’s capacity is reduced – currently only one plant is running i.e. at 33% capacity – the water vapour which was retained previously comes down leading to rainfall.

As such incidence of drought – rainy weather conditions could be easily predicted – of course in the absence of other predominantly significant events – by looking at what capacity the only coal power plant in Sri Lanka is running rather than by waiting for a weather forecasting agency in a faraway country like Australia, Japan or USA to announce that an El Nino has commenced. This inward looking approach is more relevant for Sri Lanka due to its specific location and the exceptional atmospheric circulations as depicted by Hadley and Walker Circulations.

El Nino and La Nina

Furthermore, in this particular article to Daily FT the team refers to an article titled ‘Finescale Evaluation of Droughts in a Tropical Setting’ written by Dr. Zubair, Vidura Ralapanawa and Yahiya Z. This article talks about the relationship between ENSO and weather conditions in Sri Lanka. This article says very clearly that ‘During boreal Autumn, statistically significant (p<0.05) positive correlations are seen for all four regions of Sri Lanka, indicating the well-established tendency for warm (cold) ENSO events to be associated with above (below)expected seasonal rainfall during this period’. 

Narasinhan K. Larkin and D.E. Harrison of Washington University in an article written in December 2000 titled ‘ENSO Warm (El Nino) and Cold (La Nina) Event Life Cycles’ defines Warm and Cold ENSOs as El Nino and La Nina. So despite what Dr. Zubair attempts to establish as the relationship between the drought we experienced lately and El Nino, all historical references refer to the opposite relationship. This particular referenced article by Dr. Zubair et.al also refers to a protracted drought Sri Lanka has experienced in 2001-2002 which affected our public health, agriculture, water supply and hydro power generation leading to a 1% drop in the GDP growth rate. 

But in between 1999 and 2003 there had been no El Nino and this particular drought is nothing when compared to 2013-2014 if evaluated using the WASP Index plot given in the current article. So what we want to emphasise is that the droughts – even those very severe droughts we have been talking about – we had been experiencing even with El Nino or La Nina in the past is nothing compared to the droughts we are experiencing with our one and only coal power plant which is yet to run at 80% capacity utilisation over a one year period.

Conclusion

As such, while we express our indebtedness to the researchers at FECT for their illustrative article, we beg to express our strongest disagreement with their assignment of El Nino as a possible reason for the droughts we experienced; what we would say is that in spite of an El Nino situation in the region, we had experienced a severe drought – the second in three years – and it is most probably due to the excessive CO2 generated by the one and only coal power plant in the country. May we also say that if not for the El Nino the drought would have been much worse and would have surpassed every drought we had experienced up to now in respect of its impact on the economy, environment and even the overall energy situation.

(The writer is Managing Director of Somaratna Consultants Ltd.)