Zimbabwean scientists unravel El Nino origins

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A new study by two Zimbabwean climate science experts could make it possible to predict El Nino Southern Oscillation (ENSO) ENSO several months before its occurrence.

By Sifelani Tsiko

Climate experts say ENSO is one of the most important climate phenomena on earth due to its ability to change the global atmospheric circulation, which in turn, influences temperature and precipitation across the world.

Image result for Prof  Desmond Manatsa
Prof  Desmond Manatsa

In this study, Prof  Desmond Manatsa (picture), a climate science researcher from Bindura University of Science in Zimbabwe and Geoffrey Mukwada from Free State University in South Africa made great strides in unraveling how the El Nino Southern Oscillation (ENSO) is initiated and sustained in the tropical Pacific.

This has always eluded climate scientists for years. This unresolved puzzle limited the successful predictability of ENSO events with reasonable lead time with climate scientists only able to know with some degree of certainty that the event will occur once it has started, just a few months before its impacts.

This work was published in the journal Nature Scientific Reports recently.

The Zimbabwean climate experts say the high frequent occurrences of ENSO and the associated impacts cost the world the lives of thousands of people and several trillions of US dollars in terms of its impact.

 However, in this new study, Prof Manatsa is upbeat that a lot of headway has been made towards unraveling the mystery of ENSO origin.

“We are quite excited if the possibility that the ENSO development which may not have been realistically represented in the climate forecasting models can now be improved,” he told Zimpapers Syndication.

“The necessity of the inclusion of the solar energy changes due to ozone alterations in the upper atmosphere should significantly impact on the realistic version of ENSO in climate models. This in turn should not only provide more accurate ENSO forecasts for the region but a longer lead time for users to prepare for the event.”

In this new study, Prof Manatsa and Mukwada presented evidence that ENSO is initiated and sustained from ozone changes in the upper atmosphere and not from the tropical Pacific Ocean as was currently widely believed by climate scientists.

ENSO is a climate phenomenon based in the tropical Pacific Ocean but whose events bring good rains and even floods in some years and droughts in others, over most parts of the world depending on whether the phenomenon is in a warm or cold phase.

The warm phase is referred to as El Nino when the waters over the tropical east Pacific are heated up but when cooled, it is termed La Nina.

La Nina was responsible for the favorable rains over much of southern Africa including Zimbabwe this last 2016/17 rainfall season and the El Nino occurrence a year before had devastating drought effects that was characterized by scorching heat.

“Although ENSO is the most widely and intensely researched climate phenomenon because of its huge impact on the society and the environment, climate scientists have made little headway in trying to give ENSO predictions that provide enough time to adequately prepare for the related impacts,” the researchers say.

“Since the discovery of ENSO’s socio economic impacts to date, defining ENSO’s origins have always been elusive. The resulting limited capacity to predict ENSO with reasonable lead time juxtaposed against the high socioeconomic impacts globally and particularly on southern Africa whose economy is less resilient to climate disturbances because of its inherent dependence on rainfed agriculture motivated me and my colleague Mukwada to look for solutions.”

In their drive to resolve this ENSO origin puzzle, the two climate researchers became convinced that their fellow climate scientists were making little progress because they were searching for the answers in the wrong place.

Manatsa and his colleague started to look for the source of this ENSO phenomenon in the upper atmosphere instead of the naturally expected location, the tropical Pacific Ocean surface.

This resulted in the revelations that ENSO is most likely initiated and maintained from ozone changes in the upper atmosphere.

In this way the missing link which is probably going to make it possible to make significant strides in the ENSO prediction was exposed.

“There has always been a forecast barrier to ENSO probably due to the unknown mechanisms with regard to how it is initiated in the Pacific,” says Prof Manatsa. “But with the revelation in our study of how the phenomenon is started, this inherent barrier could be overcome during ENSO forecasting.”

In the study, the researchers further note that: “The research findings are poised not only to improve the representativeness of ENSO physics in models but the simulation of the current climate thereby enhancing the accuracy of future Climate Change projections.

“The provision of successful predictions of ENSO events with reasonable accuracy and enough lead time for governments and farmers may save not only lives and money over southern Africa but the world at large.”

This is not the first time that the southern African climate scientist, Prof Manatsa has produced research results of global importance.

In 2013, he was the first climate scientist to demonstrate that the ozone hole formations over the Antarctica had significant impacts on the surface temperatures of Southern Africa.

Prof Manatsa, working with colleagues from the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) used reanalysis data to compare the climate of southern Africa before and after the development of the Antarctic ozone hole.

They found that a shift in Southern Hemisphere circulation resulting from the development of the ozone hole coincided with the intensification of a low pressure system over southern Africa — which in turn, was associated with the flux of warm air from the lower latitudes to southern Africa.

For years, scientists have been struggling to solve how to foresee an El Nino many months or years in advance.

“This is more than a question of pulling out the umbrella before the rain comes. It’s a question of understanding a pivotal and fundamental part of the Earth’s climate,” observed one renowned climate expert.

The El Nino–induced drought that ravaged the entire SADC region in the 2015-2016 farming season killed 643 000 livestock estimated to be worth close to US$2 billion according to the Sadc Climate Services Centre.

Livestock updates from across the region indicated that cattle, sheep and goats died as drought tightened its grip on the SADC region.

The livestock population in SADC is estimated at 64 million cattle, 39 million sheep, 38 million goats, 7 million pigs, 1 million equines and 380 million poultry. An estimated 75 percent of the said livestock population is kept under smallholder traditional systems.

Poor rainfall and a combination of above-average temperatures limited crop development and pasture regrowth.

Livestock production was severely affected and most smallholder farmers were forced to sell agricultural assets which they are still struggling replace even up to now.

The El Niño drought was the worst recorded in more than 50 years and apart from people saw livestock suffering from lack of grazing pasture and water.

In drought-prone parts in the Sadc region, most rivers, boreholes and weirs dried up and most people got water from shallow wells dug on sand riverbeds to water their livestock.

Sadc member states declared the 2015 – 2016 season drought a regional disaster, paving the way for donor agencies to assist in mobilising US$2,8 billion which was required for food aid for millions of people facing hunger.

Drought left up to 40 million people in need of food assistance across the region, according to the UN Food and Agriculture Organisation.

Out of this, 23 million require immediate assistance.Zimbabwe was one of the worst affected countries by the driest year in decades facing southern Africa – including Malawi, Zambia, Lesotho, Swaziland and South Africa.

The impact of the drought that swept across the SADC region in the past two years was felt across all sectors including agriculture, food and nutrition security, tourism, energy, health, water and sanitation and education.

However, good rains in the 2016 – 2017 cropping season brought by the La Nina effect brought cheer to most people across the entire region despite floods killing people and destroying crops, livestock and assets running into the thousands of dollars.