How El Nino will impact us

by K.R. Abhayasingha

According to the Gregorian calendar, the year 2016 has commenced. The last lap of 2015 slipped through us, leaving several serious natural hazards caused by extremely intense rainfall between October-November of 2015 over most parts of the island.

Climate impacts of warm El Nino effects (ecosystems.wcp.muohio. edu)

The international climate and geographical institutes reported on a phenomenon called the El Nino and warned the world that it may be severe than the 1997 El Nino , the worst to occur during the recent past, and predicted of extreme weather parameters that can affect most regions of the world. Local media also devoted space and time to clarify further through meteorological officials, about El Nino's influence.

Close relationship

El Nino has become a very important topic in the past few decades due to statistical analyses demonstrating a close relationship between periodical extreme weather conditions and the El Nino events.

Among the causes for the periodical droughts in Sri Lanka, El Nino seems to be most important. Not only drought situations in Sri Lanka but also some extreme weather conditions leading to natural disasters of all types, locally and globally, are triggered off by El Nino events.

But in the past, El Nino has been regarded as a problem or a disaster for the fisheries industry in South American villages. For hundreds of years, fishermen living in coastal villages in Peru and Ecuador have known El Nino. Once or twice in each decade, the normally cooler waters along South America's shores would warm and the fish would begin to die. Then the seabirds dependent on fish for fodder would starve by the thousands. The villagers' lives and livelihoods would suffer when the fish are gone - their key source of income.

Fishermen named this event as 'El Nino,' a Spanish word that means: 'The Little Boy' or 'The Christ Child' because the phenomenon usually happened around Christmastime and sometimes stretched far into the New Year. But as time elapsed, El Nino would fade, the ocean temperatures would return to normal and the great shoals of fish would return.

Under normal global conditions, the waters over the Eastern Pacific are cooler (24-25 degrees Celsius) than those of the Western Pacific (27-29 degrees Celsius) near Indonesia, Australia and Papua New Guinea. This temperature distribution supports the maintenance of the large air circulation cells over the globe and these primary wind cells are the main energy engines developing the global climate.

But as it has been observed by the fishermen for decades, the sea waters of the Eastern Pacific warms every three to five years. If the warming is significant, the wind cells start changing their orientation first over the Pacific and then at a global scale. These changes in the global circulation usually end up with unexpected and significant changes in weather patterns globally.

Consequences

In the days before radio, television and satellite communications technology were developed, South American fishermen probably had no idea what other far-reaching climactic changes an El Nino produced beyond their shores. They couldn't have known that entire continents suffered strange or reversed weather patterns, or that arid regions were hit by torrential rains while tropics suffered severe droughts. Sometimes, snow fell where none had been seen for decades.

Effects of El Nino (.rackcdn.com)

While South American scientists have been aware of El Nino for a long time, their North American counterparts hadn't collected much data about this weather event, how it's formed and its potentially disastrous worldwide consequences. After the devastating El Nino of 1983, the scientific community began taking more serious notice and to gather the critical historical climate data they needed to learn about the El Nino effect. Studies have shown that past events with deteriorated weather parameters over many regions were correlated with the El Nino events.

Some of our scientists have shown that the El Nino events or 'Warm Pacific Episodes' affect weather situation over Sri Lanka too. Analyses of past climate data have revealed that the second inter monsoon season (October-November) is wet with heavy rains over many parts in parallel with warming of Pacific waters and the first inter monsoon (March-April) and south west monsoon (May-September) seasons in following year fails to produce normal rain falls and therefore the environment leads to drought conditions over many parts.

The accuracy of statistical analyses and predictions depend on the size and the origin of the data sets used for analyses and therefore, conclusions approached in other data analyses performed later may provide us different predictions.

It is the responsibility of all relevant institutes and people to consider seriously the variations of Pacific temperature patterns on a regular basis. The modern communication facilities have made this task easy for anyone who has the interest. Data observed over Pacific and other oceans are analyzed by a number of institutes including the World Meteorological Organization (WMO) and the results are available.

Assessing intensity

It has been accepted by the world science community to estimate the intensity of the El Nino by calculating indices using the surface pressure values observed at two meteorological stations one at Darwin, Australia and the other at Tahiti, in the Pacific.

Since the El Nino is related to the warming of the Pacific waters, the bad effects of the current trend of global warming has to be concerned as a supporting parameter enhancing El Nino development. World scientists have already warned the nations about the expected hazardous effects of global warming which will result in changes of the climate. It has also been disclosed by scientists that global warming will increase the frequency of El Nino effects.

A number of human activities have been identified as main reasons leading to global warming and such matters were deeply discussed in all recent scientific forums including the recent climate conference in Paris.

If the prediction based on past data analyses is regarded as fairly accurate, all concerned should be alert to various environmental changes because we may be heading towards the El Nino- caused effects. If the trend is positive, all precautionary steps should be taken by all of us towards management of water which is the most required in drought situations.

As the warming of the Pacific waters has a tendency to induce the warming effect, the weather over many regions may show fluctuations from the normal. Hence the atmosphere around Sri Lanka in January may not be cold and pleasant as expected. Instead we may have to entertain unusually warm weather in some days, even in January.

About the author:

K.R. Abhayasingha is a visiting lecturer at the Post Graduate Institute of Science (PGIS) of the University of Peradeniya and a retired Director of Meteorology.